NASA CR- 175033

QRGANOSILOXANE WORKING FLUIDS

FOR THE

LIQUID DROPLET RADIATOR

-CR- 175033) OBG ANGSILOXfiNE HORKING N86-16381

FLUIDS FOB THE LIQUID DBOP1ET BADIATOS

Final Report (Dow Coming Corp.) 174 p

HC AQ8/MF A01 CSCL 1 1G Unclas

• _ • _ _ G3/27 05250

BY - - -

R.R. BUCH

A.R. HUNTRESS

DOW CORNING CORPORATION

PREPARED FOR

NATIONAL AERONAUTICS KP*W

SPACE ADMINISTRATION

NASA LEWIS RESEARCH CENTER

CONTRACT NAS 3-24400
ACKNOWLEDGMENTS

These individuals contributed to this effort by their efforts on

the following property measurements:

1. Liquid Chromatography

2. Infra-red Spectroscopy

3. NMR Spectroscopy

4. Viscosity and Selection of

Fluid Candidates

5. TGA Measurements and

Specific Heat

6. Surface Tension and Density

7. Flammability Parameters and

Electrical Properties

Mark Becker and

Gene Sumption

Thien Ho

Dr. Thomas Carr

Eugene Groenhof

Kathleen Panichella

Daniel Filsinger

Ora Flaningam

Don Ingebrigtson

The authors wish to cite the exceptional skills of Dr. A. Lee

Smith for his expertise and measurements on the absorptive and

emissive characteristics of the Task II fluids

P8ECEDIH9 PAGE BLANK NOT BM»EP

"

111

PAGE //* fflTENKONACa KAMI
TABLE OF CONTENTS

Page

SUMMARY. . . 1

INTRODUCTION 2

TASK I. SCREENING CANDIDATE FLUIDS 3-12

Selection of Five Candidates for Screening 3-5

Isolation of Task I Fluids 5

Fluid Description 6-7

Measurements/Viscosity and Vapor Pressure 7-12

TASK II. EVALUATION OF TWO FLUIDS 13-26

Selection of Fluids 13-14

Isolation of Task II Fluids 14-15

Fluid Characterization 15

Density 15-16

Surface Tension 16

Heat Capacity 16

Thermal Conductivity 16-17

Electrical Conductivity 17

Pour Point 17

Flash Point 18

Fire Point 18

Viscosity-Temperature 18

Viscosity-Shear Dependence 18-19

Vapor Pressure 19-20

Heat of Vaporization 20

Emittance and Transmittance 21

Thermal Stability,'Oxidative Stabirity/Stability ~ ~ ~ -

Against Radiation, and Operating Lifetime 21-22

Thermal Effects 22-23

Oxidative Effects 23-24

Effects of Radiation 24-25

Flammability 25-26

Toxicity 26

TASK III. FURTHER DEVELOPMENT, QF .FLUIDS 27

CONCLUDING REMARKS 28

REFERENCES. 29-30

IV
TABLES I - X

FIGURES 1 - 33e

APPENDIX I - Target Vapor Pressure for LDR Fluid

APPENDIX II - Test Methods and Equipment

APPENDIX III - Test Reports

Thermal Conductivity

Viscosity-Shear

Emittance and Transmittance

APPENDIX IV - Acute Toxicological Report on Dow Corning®

710 Fluid

APPENDIX V - Nomenclature

v
SUMMARY

The objective of the work reported here was to evaluate siloxanebased fluids as working fluids for the Liquid Droplet Radiator.

Over an operating temperature range from 255 to _394K, working

media need to have viscosities below about 25 x 10~6 m2/sec, and

vapor pressures less than 10

 7 Pascals. These properties and the

heat transfer properties of the fluids must be retained during

long missions in the environment at the orbital altitude of the

Space Station. The environmental factors include vacuum of about

10

 6 Pascals, collisions (5 eV) with atomic oxygen, and energetic

radiation, both particulate and solar.

Five candidate fluids were recovered by vacuum distillation

from existing siloxane polymers. Candidates included a polydimethylsiloxane, three phenyl-containing siloxanes, and a

methylhexylsiloxane. Vapor pressures were approximated from

evaporation rates in TGA under vacuum, using Dow Corning® 704

Fluid as a reference standard.

Polydimethylsiloxane (PDMS) and polymethylphenylsiloxane (PMPS)

were selected for further characterization. Both fluids

consisted of narrow molecular weight distributions with average

molecular weights of about 2500 for PDMS and 1300 for PMPS.

The fluids were characterized by IR, Si29 NMR, GPC, and LC.

Properties measured as a function of temperature included

viscosity, viscosity/shear dependence, vapor pressure, density,

surface tension, specific heat, thermal conductivity, and

electrical conductivity. Pour points, flash points and fire

points were measured. Heats of vaporization were calculated from

the vapor pressure/temperature relation. IR emittance and

transmittance of thin films were determined.

A search of siloxane literature provided the basis for discussion

of the thermal, oxidative, and radiation stability of the

siloxane families. Flammability and toxicity are also discussed.

Routes for adjusting viscosity, vapor pressure, and stability

against elements of the LDR environment are suggested.

The requirement for low viscosity combined with low vapor pressure has been met in these siloxane fluids. Lighter fractions

may optimize viscosity for operations in the lower end of the

temperature range. Existing information on the reactions of

atomic oxygen with siloxane fluids is probably inadequate for

predicting service life in the unique combined environment of the

LDR, or for directing further development of stabilized versions,

if necessary.
INTRODUCTION

The Liquid Droplet Radiator (LDR) (Ref. 1) is a new approach to

rejecting heat in space, in which waste heat collected in a space

system by a circulating fluid is radiated into space directly

from the surface of liquid droplets. An unusual fluid or family

of fluids is required to perform this function. Temperature of

the fluid may be 255 to 394K (0 to 250°F). Vapor pressure at the

operating temperature must be extremely low to minimize

contamination of the space system or loss of fluid by evaporation

when exposed to the space environment. Viscosity must be low to

facilitate pumping at low power cost and collection of droplets.

The fluid must survive years of exposure to the space environment

at orbital altitude without significant change in physical and

thermal properties. Environmental factors include vacuum of

about 10

 6 Pascals, collisions (5 eV) with atomic oxygen, and

energetic radiation, both particulate and solar.

In the first stages of the joint Air Force Rocket Propulsion Lab/

NASA-Lewis Research Center program on the LDR, phenyl-containing

siloxanes [tetramethyltetraphenyltrisiloxane (1) and trimethylpentaphenyltrisiloxane (2)] were considered as candidate fluids,

having low vapor pressures and resistance to oxidation and

radiation.

It was the objective of the work described here to evaluate other

existing siloxane-based fluids as working fluids for the Liquid

Droplet. Radiator. First, five candidate silicone fluids were

identified for screening on the basis of vapor pressure and

viscosity (Task I). Following review of the results of Task I,

two of these fluids were selected for further characterization

(Task II) . Measurement methods and properties are described in

this report.

Following the -exploration and—measurement - phases--(Tasks I -andII) , recommendations are made concerning silicone fluids that

might be. synthesized or formulated to optimize performance in the

LDR.

Operating life of the fluid in the LDR environment is affected by

thermal stability, oxidative stability, and resistance to

radiation. A search of the technical literature related to these

subjects was carried out.

(1) Dow Corning 704 Fluid

(2) Dow Corning 705 Fluid
TASK I. SCREENING CANDIDATE FLUIDS

Selection of five candidates for screening.

Requirements for the initial candidate fluids were:

Silicon-based

Available

Viscosity - preferred 1 x 10~6 to 25 x 10~6 m2/sec

(1-25 cs) at 255-394K or over a substantial

segment of that temperature range.

Vapor Pressure - less than or equal to 10~7 Pa (^10~9 torr)

at 394K.

Ideally a single fluid should satisfy the full operating range of

255-394K. However, since low vapor pressure and low viscosity

tend to be incompatible properties, an alternative would be to

use two or more fluids, each suited to a segment of the

temperature range.

An estimate of the allowable vapor pressure was made from the

Knudsen model for evaporation at conditions of molecular flow

(Appendix I). Droplets having diameters of approximately 0.Iran

are proposed. The resulting high ratio of surface to volume

maximizes the fraction evaporating. Fractional evaporation rate

is inversely proportional to diameter of the drop. For a vapor

pressure of 10

 7 Pa, evaporative loss might be 10% or more per

year, assuming that 10% of the fluid volume is exposed as

droplets. Figure 1 shows the target vapor pressure in relation

to the vapor pressure of 704 and 705 fluids. It should be noted

that for materials of this 'molecular size, vapor pressure varies

sharply with temperature. Lowering temperature by 10-15K reduces

vapor pressure tenfold.

Projecting from vapor pressures of known siloxane products and

compounds, it was clear that the necessary vapor pressure would

occur in material with molecular weight over 1000 for the case of

methylphenylsiloxane and over 2500 for dimethylsiloxane. Review

of current products and materials being developed identified no

compositions of these sizes except as they occurred as members of

homologous series constituting polymeric products. In these

polymers, either vapor pressures or viscosity would be high,

depending on their distribution of molecular weights.

It was concluded that the most probable ready source for LDR

fluid candidates would be distilled fractions from polymeric

fluids. As recovered by a single stage vacuum distillation, the

fluid fraction would be of narrow molecular weight distribution

(low dispersity). For a given vapor pressure, the narrow distribution approaches the lowest viscosity possible for the specific

polymer family. A single compound would be ideal. Again

projecting from the vapor pressure/temperature relations known

for more volatile members of siloxane homologous series, it

appeared that the desired polymer fractions would distill in the

range of 573 to 623K at 13 Pascal (0.1 torr).
The following polymer families were selected for distillation:

1. Me3SiO(MePhSiO) SiMe3 Me = CH3; Ph = C6H5

Phenyl sidegroups improve the resistance of siloxanes

to oxidation and radiation. The ratio of phenyl to methyl

constituents here is similar to that of 704 fluid. Viscosity would be higher than desired at low temperature.

2. Ph,MeSiO(Me,SiO 2 2 ) (MePhSiO) SiMePh,

 n m z

This polymer exists in the high-boiling residue of the

process used to make 704 fluid. The presence of phenyl as

end groups has the possibility of raising surface tension

and/or showing a different relationship between viscosity

and vapor pressure from that in (1) above.

3. Me3SiO(Me2SiO)n(MePhSiO)mSiMe3

The commercial source for this polymer has n approximately equal to m. It is expected that the narrow distillation cut would retain this ratio. This fluid, because of

its lower phenyl content, would show less oxidative

stability than (1) above, but lower viscosity.

4. Me3SiO(Me2SiO)nSiMe3

Polydimethylsiloxane (PDMS) would have the highest

chain length and molecular weight for a given vapor

pressure, but lower viscosity, especially at the lower end

of the LDR temperature range. While it is more susceptible

to oxidation and damage by particle radiation, it is more

transparent to ultraviolet radiation and possibly less

affected.

5. Me,SiO(Me,SiO J ) (MeHexSiO) SiMe, Hex = Cf iH13 * _ n m j D13 . .

The hexyl ligand offered the possibility of lower viscosity than in PDMS having the same vapor pressure. With

the hexyl ligand, the chain length will be shorter, and

consequently of lower viscosity. It would be necessary that

the contribution of hexyl to viscosity be less than that of

phenyl. A penalty in oxidation resistance, compared to

PDMS, would be expected.

Branched methylsiloxane polymer was considered as the fifth

candidate rather than the hexylmethyldimethylsiloxane chosen.

For polymers of the same molecular weight, branched structure is

frequently found to give lower viscosity. Inspection of specific

pairs of branched and linear compounds with molecular weight

somewhat less than the LDR range showed the opposite effect, so

this approach was abandoned.
Isolation of Task I Fluids

A fraction having narrow molecular-weight distribution was

isolated by vacuum strip distillation from each of the five

polymeric systems.

Equipment;

Conventional Pyrex® laboratory glass apparatus

1-liter three-neck strip pot, air-cooled pear-head

condenser, demountable connectors with taper or

spherical glass joints, sealed with siliconebased vacuum grease

Electric heating mantle with Variac control

Magnetic stirrer

Pyrex receiver, 500 mL

Oil-sealed mechanical vacuum pump, 2-stage, capable of

blank-off pressure <1 Pascal (^0.01 torr)

Pressure measurement by tilt-McLeod mercury gauge,

connected by vacuum hose at the strip pot

Temperature measurement by mercury thermometers

Procedure;

The source fluid was weighed to the strip pot. The system

was assembled and vacuum was applied. Heat was regulated to

give moderate rate of distillation. The pot temperature was

taken to 631-653K (358-380°C) at 12-26 Pascal (0.1-0.2

Torr), (114 Pascals in one case), carrying the LDR fraction

and the more volatile species overhead. The pot was cleaned

and the distillate reloaded for topping. Volatiles were

stripped to 548-582K (275-309°C), at 12-18 Pascals. The LDR

cut remaining as bottoms was filtered through 0.45-

micrometer paper. Insoluble dimethylsiloxane polymer -from

the vacuum grease made the phenyl-containing fluids hazy.

Haze was removed by adding filteraid before filtering.

Table I shows specific cut conditions and distribution of

fractions for each fluid.

The first fluid stripped was polymethylphenylsiloxane. Gas

chromatography was used with an internal standard

(Me3SiO(MePhSiO)3SiMe3) to estimate the molecular sizes

recovered with the selected strip conditions. Compounds

through Me3SiO(MePhSiO)?SiMe3 were eluted. Species with

n = 6 and 7 were major in the topping volatiles and were

present in the LDR cut. This suggested that the bulk of the

LDR cut would have n = 8-10. • •
Fluid Description

The general formulas for the five Task I fluids selected for

vapor pressure and viscosity characterization are:

Ph,Me

Me

PhSiO

Ph

Me

SiO

Me

Ph

SiO

Me

Ph

SiPh

Me

x and y were not determined for this fluid.

MePh

Me

Me SiO

Me

Ph

SiO

Me

Me

SiMe

Me

X

where x avg. = 8 to 9

Me,/MePh

Me

Me SiO

Me

Me

SiO

Me

(A)

x

Ph

SiO

Me

-

(B)

Me

SiMe

Me

where (x=y) avg. = 7-8

The A and B units are not necessarily regularly repeating

units since this material results from a random copolymerization. The structural formula refers to an average

molecular composition.

Me.

Me

MeSiO

Me

Me

SiO

Me

Me

SiMe

Me

x

where x avg. =34

Hex Me/Me,

Me

MeSiO

Me

Hex

SiO

Me

- _ x

Me

SiO

_M _ e

Me

SiMe

Me

y

(A) (B)

where x avg. = 7

v avg. =17

Hex = C6H13

The A and B units are not necessarily regularly repeating

units since this material results from a random copolymerization. The structural formula refers to an average

molecular composition.
Molecular weights and size distribution of these fluids were

measured using gel permeation chromatography (GPC). GPC calibration data relating molecular weight to retention time are given

in Figure 2. GPC calibration was accomplished using either pure

compounds or narrow distribution standards of known molecular

weight. Number average (M J1 and_weight average (M )2 molecular

weights and dispersity indices (M /M ) are summarised in Table

II, A typical chromatogram is given in Figure 3. The estimated

accuracy of these molecular weight values is ±10%.

The Ph2Me and MePh fluids were also characterized in terms of

molecular composition using reverse-phase liquid chromatography

(LC) . These materials consist of three to five major molecular

entities, each differing by a single "mer" unit. Chromatograms

of these two fluids are given in Figure 4.

A description of the GPC and LC units is given in Appendix II.

Measurements

Viscosity and vapor pressure of each fluid were measured.

Kinematic viscosity was measured as a function of temperature

over the range 255 to 394K (0° to 250°F) using Ubbelohde glass

capillary viscometers. Viscometers were calibrated using oils

certified by the National Bureau of Standards (obtained from

Cannon Instrument Co., State College, PA.). Measurement procedures followed those described in Corporate Test Method (CTM)

0004 (Appendix II). CTM(s) are generally based on a corresponding ASTM Method. Minor deviations between our test procedure and the ASTM Method do occur, e.g. - frequency of

calibration. Both accuracy and precision for these viscosity

data are estimated to be ±2%. Viscosity data are summarized in

Table III and Figure 5.

A correlation is evident between fluid structure and the effect

of temperature on viscosity. Those fluids with phenyl substituents on either the end groups or the polymer backbone exhibit a

substantially greater viscosity-temperature dependence, especially at low temperatures. Furthermore, the influence of a

permethylated mer unit on viscosity is evident from a comparison

of the MePh fluid to the Me2/MePh fluid, and the Me2/MePh to the

Me2 fluid. Although the Me2 fluid has the highest molecular

weight and longest polymer chain length, it is the lowest

viscosity fluid and exhibits the lowest dependence of viscosity

on temperature.

Measurement of the vapor pressures of these fluids posed a

formidable problem for two reasons. First, all of the fluids

were distillation cuts from polymeric materials and as such

consisted of a distribution of molecular species of similar

chemical structures but different molecular chain lengths.

2.' M = En.M.

 2

.w i i

En. M". i i
While extensive care and effort was expended to obtain as narrow

a distribution of chain lengths as possible, the lowest molecular

weight components still significantly influence the measured

vapor pressure and fluid composition changes during measurement.

Second, the measurement of vapor pressure in the targeted

pressure range, 10

 7 Pa, is difficult. A number of methods using

sophisticated thermal analytical techniques have been reported

(Ref. 2, 3). However, methods useful below about 10

 3 Pa require

a high degree of sophistication, such as the use of radioactively

tagged materials. A recently developed technique, thermal

evolution analysis (Ref. 4), has been demonstrated to be

effective in our range of interest. However, considerable time

and effort would be required to establish this technique.

Most of the cited methods are based on the Knudsen effusion

equation (Ref. 5):

/ \ Am 1 (2^ RT) (1)

At * q * M '

Where: P = vapor pressure

R = ideal gas constant

q = orifice area

= mass loss rate

At

T = temperature (K)

M = molecular weight

In our approach, mass loss rates (evaporation rates) were

obtained using" a - DuPont 1090' --thermogravimetric "analysis (TGA)

system (Appendix II) . However, the Knudsen equation did not

apply directly. In our apparatus the requirement of thermal

equilibrium between liquid and vapor phases of the evaporating

sample was not necessarily met. In the Knudsen method this is

accomplished by severely limiting the evaporation rate. The area

of the vapor orifice is small compared to the sample surface. In

our TGA approach, evaporation from the sample surface area (0.785

cm2) was not restricted in this way. However, deviations from

thermal equlibrium were minimized by using very low evaporation

rates. The Knudsen equation (1) also requires uninhibited

molecular flow, i.e. operation at pressures <10~2 Pa (10~^ torr).

In our TGA apparatus, pressures of approximately 60 Pa (0.45

torr) could be conveniently maintained. The deviation from the

requirement of unrestricted molecular flow was overcome by using

an appropriate low vapor pressure standard fluid. For this

standard, Dow Corning 704 Fluid was selected because of its low

volatility and the availability of reliable vapor pressure data.
The Knudsen equation was applied as follows. Combining all

constants in equation (1) , together with a constant to represent

the departure from uninhibited molecular flow, we obtain

P .. £ . K (T/M)

1/2

or the evaporation rate is given by

1/2

(M/TJ

At "' K '

For the standard fluid (DC-704),

m704 P704,T

K

M

704

1/2

Similarly, for the test fluid,

mx,T ~ Px,T

K

M 1/2

(2)

(3)

(4)

(5)

Dividing (4) by (5) and solving for the vapor pressure of the

test fluid at temperature T, we obtain

x,T

m

^704, T

(

P704,TJ

M

704

~M

x

(6)

With this relation, vapor pressures were measured as follows:

1. Obtain dynamic programmed TGA of the test fluid to establish

the range of temperatures for evaporation rate measurements.

2. Perform isothermal evaporation rate measurements at constant

pressure and several temperatures over this range.

3. Using a least-squares method, fit mass-loss for the test

fluid and for the reference fluid DC-704 to the equation

log..- m = A-B/T (7)

Calculate from equation (6) the vapor pressure at each test

temperature for the test fluid. The vapor pressure (torr)

for 704 is given by

Iog10 P?()4 = 7380 - 10.07 log T + 42.05 (8)
The experimental set-up and procedures were as follows:

1. Load 80 to 90 mg. of the test fluid into the circular sample

pan suspended from the lever arm of the TGA unit.

2. Clamp the glass envelope of the TGA unit securely into

position.

3. Commence evacuation of the TGA sample chamber. A conventional mechanical vacuum pump is capable of providing the

required working pressure of 0.45 torr. Pressure was

regulated by air bleed through a micro-metering valve.

Vacuum was monitored with a McLeod gauge.

4. Following evacuation of the TGA unit to a pressure of 0.45

torr, an initial devolatilization of the fluid was accomplished by heating the sample at a moderate constant temperature so as to evaporate 8-10 mg in 30 to 60 minutes of

heating. This was intended to remove any adventitious low

molecular weight decomposition products in the fluid which

may have resulted from the stringent distillation conditions.

5. The TGA chamber was allowed to cool and the microprocessor

was programmed for a series of mass loss measurements at

selected constant temperatures.

6. The mass loss measurements commenced; mass of the samples

was tracked by the microprocessor data unit. A typical

series of mass loss measurements is given in Figure 6.

7. Evaporation rates were calculated for each temperature. The

computer graphics system was used to expand each mass loss

increment. The procedure is illustrated in Figure 7.

In Figure 8 the experimental evaporation rates for 704 Fluid are

compared with the calculated mass loss curve for 704 under

Knudsen effusion conditions, i.e. unrestricted molecular flow and

liquid-vapor equilibrium. The difference in rates is of the

order expected for the system pressure. The consistent

systematic shift at all temperatures suggests that deviations

from vapor-liquid equilibrium were minor or at least consistent.

To test the sensitivity of evaporation rate to system pressure,

the evaporation rates for the 704 reference fluid were measured

at 60 and 100 Pa (0.45 torr and 0.75 torr). The slight shift in

two rate curves (also in Figure 8) suggest that control of system

pressure to ±0.05 torr is adequate.

10
In Figure 9, three series of measured mass loss rates are given

for a single fluid. Run 1 was measured at higher temperatures

than Runs 2 and 3. At high temperature, loss rate slowed

appreciably during each temperature step as the composition of

the sample and possibly that of the sample surface with respect

to the bulk changed. Also, the temperature of the sample surface

may fall below the indicated temperature when the rate of

evaporation is excessive. Runs 2 and 3 demonstrate the repeatability of the mass loss rate measurements at lower temperatures

and lower loss rates.

Mass loss rates for the five Task I fluids are given in Table IV

and plotted in Figures lOa through lOe. For each fluid two

series of mass loss rates were measured, as for example in Figure

lOd, Series 1 and 2. In Series 1, loss rates were measured at

progressively higher temperatures. After completing this series,

the measurements were repeated on the same sample beginning at

the low temperatures of the previous series. The difference in

loss rates and slope between Series 1 and 2 is the result of

changing composition of the fluid during Series 1. Series 2

better represents a fluid of constant composition, although

somewhat heavier than the original fluid. The slope of the

Series 2 data is appropriate for calculation of heat of

vaporization of the fluid or extrapolation of the derived vapor

pressure curve to lower temperature, i.e. those anticipated in the

LDR. Typically, 25 to 30% of the initial fluid charge was

evaporated in the first series of measurements.

The evaporation rate data for each fluid were fit to equation

(7). The results of these data correlations are as follows:

704 Reference Fluid

Iog10 m = 8.47972 - 5528

Me,/MePh

(Series 2)

Iog10 m = 12.98668 - 9739

Me.

(Correlation Coefficient

0.9980) (6 data points)

(Correlation Coefficient

0.9978) (5 data points)

(Series 2)

login m = 13.81766 - 10197

10 T

HexMe/Me,

(Series 2)

m = 12.75908 - 9350

(Correlation Coefficient

0.9977) (5 data points)

(Correlation Coefficient

0.9977) (6 data points)

11
MePh

(Series 2)

Iog10 m = 12.85558

Ph,Me

(Series 2)

log1Q m = 12.16102

- 9545 (Correlation Coefficient

T 0.9993) (3 data points)

(Correlation Coefficient

0.9951) (7 data points)

Using these relationships for mass loss rates versus temperature

and the vapor pressure of the reference fluid (equation 8), the

vapor pressure for each fluid was calculated. The vapor pressures for each fluid are given in Figures lla to lie. Figure 12

shows the vapor pressure curves derived from the Series 2

evaporation rates for all five fluids. These data reflect the

estimated vapor pressure of each fluid after the removal of

20-30% of lower molecular weight species. A line of similar

slope (not shown) through the first points determined in Series 1

would better represent the vapor pressure of the original fluid.

The extrapolated vapor pressures of the five Task I fluids range

from 8 x 10~7 to 7 x 10

 8 Pa at 394K (250°F). The difference in

vapor pressures between Series 1 and Series 2 show the great

extent to which each fluid can be tailored by the selection of

distillation parameters.

12
TASK II. EVALUATION OF TWO FLUIDS

Selection of Fluids

Two of five fluid structures of Task I were selected for further

characterization. Vapor pressures and viscosities of the five

are shown as a function of temperature in Figures 12 and 5,

respectively. These data are combined in Figure 13 to show the

working temperature window for each fluid as defined by the

assigned targets for vapor pressure and viscosity. The solid bar

for each fluid extends between viscosity of 25 x 10~6 m2/sec (25

cSt) as the low temperature end and vapor pressure of 1C~7 Pa at

the high. For Me2/MePh fluid (polydimethylmethylphenylsiloxane)_,

for example, as temperature rises, viscosity falls to 25 x 10~6

m

2/sec at 333K (140°F) and vapor pressure remains below 10 7Pa

until 397K (255°F). Operating windows for all five fluids reach

nearly to 394K (250°F), the target upper limit. Topping to a

slightly stronger condition can lower vapor pressure sharply with

moderate effect on viscosity. Near 394K, with species of this

size, each MePhSiO- group (or three Me2SiO- groups) reduces vapor

pressure by about ten times.

The widest operating temperature windows occur for Me2 fluid and

HexMe/Me2 fluid, (polydimethylsiloxane and polyhexylmethyldimethylsiloxane), with target viscosity near 298K. Phenyl

substitution in the other three fluids raises viscosity, yielding

a lower temperature boundary of 333-350K (140-170°F). A lighter

fraction from any of these polymers can complete a two-fluid

system covering most of the desired temperature range.

Also shown for comparison on Figure 13 is 704 Fluid. No

operating window exists for 704 because as temperature rises, the

limit on the vapor pressure is reached before viscosity falls to

25 x 10~6 iWsec.

Since all five polymer systems provide a choice of vapor pressures by adjusting conditions in distillation, and since all five

show acceptable viscosities, at least in two-fluid modes, the

opportunity arose to consider stability as a criterion in

selection of the two Task II fluids. Potentially significant

stresses in the orbital environment are 5-electron-volt

encounters with atomic oxygen, solar ultraviolet, and particle

radiation. Original attention in the LDR program to phenylsiloxane fluids was partly in recognition of their relatively

high resistance to particle radiation and conventional oxidation.

MePh fluid (methylphenylpolysiloxane) has the highest phenyl

content of the five candidates and was selected for Task II on

that basis.

It was not possible to ascertain whether oxidation by atomic

oxygen is a significant concern. Numbers of encounters will be

far less than would be important for oxidation with air or

oxygen. Higher reactivity of atomic oxygen in collisions that

cause some ionization (5 eV) will greatly increase cross-linking

13
efficiency. On the other hand, rapid escape of volatile reaction

fragments is reported to reduce oxidation effects, again under

more conventional conditions. With the possibility that high

phenyl content would not be called upon, it was decided to keep

Me2 fluid (dimethylpolysiloxane) in Task II for its low

viscosity. Its viscosity is likely to be more stable under

ultraviolet radiation than that of phenyl systems. Finally,

should oxygen be the primary threat, additive technology may

provide a substitute for the stabilizing role of phenyl on

silicon.

Isolation of Task II Fluids

Polydimethylsiloxane and polymethylphenylsiloxane fractions for

Task II characterization were recovered in. essentially the same

way as the Task I screening samples. Approximately 0.5 kilogram

of each was isolated from eight and six liters of feedstocks,

respectively. The use of a larger strip pot (3 liters), thermal

rearrangement during strip, and different sources of feedstock

complicated the effort to duplicate or improve upon the screening

samples. At low pressure, vapor flow creates back pressure which

became significant in the larger system. At 623K, traces of

oxygen, water, or silanol groups catalyze rearrangement of

siloxanes to volatile cyclics'. These cyclics act as a vapor

carrier, making the strip of heavier species more effective. A

first attempt to recover polydimethylsiloxane was abandoned when

a trace air leak produced cyclics that severely affected the

product distribution. Polymethylphenylsiloxane was isolated from

Dow Corning 710 fluid rather than from the developmental source

of the screening case. The desired species were found near the

lighter end of the polymer distribution, as opposed to the

heavier end as in the earlier strip. These are variables which

can be controlled with further development of the strip process.

Fluids recovered for characterization are:

Polydimethylsiloxane Polymethylphenylsiloxane

Reference

Source

Strip Conditions

Pressure

Pot temp.

Vapor temp.

6758-23

Dow Corning 200

Lot MA091196

26 Pa (0.2 torr)

653K (380°C)

605K (332°C)

6758-27

Dow Corning 710

Lot MA044423

29-45 Pa (.22-

.35 torr)

643-653K (370-380°C)

587-597K (314-324°C)

14
Topping conditions

Pressure 39 Pa (0.3 torr) 52 Pa (0.4 torr)

Pot temp. . 613K (340°C) 600K (327°C)

Vapor temp. 575K (302°C) 568K (295°C)

Cut yields, %

Volatiles 82 17

LDR Cut 6 8

Bottoms 12 74

Fluid Characterization

Infra-red spectra of the Task II fluids are given in Figures 14

and 15. Si29 NMR spectra were obtained using a Varian XL-200

Multi-Nuclear NMR Spectrometer. The subject fluid was dissolved

in deuterated chloroform 50% (V/V). This solution was doped with

paramagnetic chromium-acetylacetonate to ensure quantitativeness.

The NMR spectra, Figures 16 and 17, provide molecular weights and

unequivocal confirmation of molecular structure for each fluid.

Chemical shift data derived from model compounds confirms the

identification of both mer- and end-groups for each fluid.

Absorption intensity provides a direct quantitative measure of

both mer- and end-groups. From these data, the average chain

length, including end-groups, for the fluids was determined to be

30 (±3) units (i.e. Si-O) and 11 (±1) units for the Me2 and MePh

fluids, respectively.

Polymer size distributions were obtained using GPC. MePh fluid

was also characterized by LC. The average molecular weight

(Mn = 2450) of the Me2 Task II fluid is lower than its counterpart in Task I (Mn = 2700).

The liquid chromatograph of the MePh is given in Figure 18 along

with that for MePh (Task I) . The major components of MePh (II)

and MePh (I) are nearly identical. Small amounts of more

volatile lower molecular weight species are evident in the Task

II fluid. This occurs mainly as a result of the two different

source fluids used in obtaining the desired distilled fraction.

Density

Fluid densities were measured using a Mettler/Paar Digital

Density Meter. Procedures are given in Appendix II. Water and

air provided convenient calibration media. Accuracy . of ±. 0.5

kg/m3 (± 5 x 10

 k g/cm3) is specified by the instrument

manufacturer. Data for the two Task II fluids are given in

Figure 19 and Table V.

15
Densities vary with temperature according to the following

equations:

(MePh)

(Mea)

p(kg/m3) = 1311 - 0.772 T(K)

p(kg/m3) = 1221 - 0.8878 T(K)

(9)

(10)

Surface Tension

Surface tension measurements were obtained using a Wilhelmy-plate

surface tensiometer (Ref. 6, 7). Tension on the suspended plate

was measured with a Cahn Electrobalance with 1x1 0 *" kg

(1 x 10

 7 g) sensitivity. Accuracy of this technique is

estimated to be ± 5 x lO"1* N/m (0.5 dynes/cm) . These data are

summarized in Figure 20 and Table VI. The surface tension of the

fluids vary with temperature according to the following

equations:

MePh y (N/m) = 0.0397 - 5.35 x 10~5 T(K)

(Me,) Y (N/m) = 0.0411 - 6.94 x 10~5 T(K)

(11)

(12)

Heat Capacity

Heat capacity measurements were made using a Dupont 910

Differential Scanning Calorimeter (DSC). Procedures followed

those provided by the instrument manufacturer (Appendix II) .

Instrument performance was verified by measuring the heat

capacity of a standard reference fluid for which heat capacity

data are available from earlier studies using a Bunsen icecalorimeter. The ice calorimeter data are accurate to ±0.5%.

Agreement within ±3% between ice calorimeter data and DSC data is

required for acceptance of the DSC results. An accuracy of

±5% is estimated for the DSC heat capacity results.

Heat capaci'ty data for the two Task II fluids are given in Figure

21. Temperature dependence of the heat capacity is as follows:

(MePh)

(Me2)

C (J/kg-K) = 901 + 1.93 T

C (J/kg-K) = 1058 + 1.66 T

P

(13)

(14)

Thermal Conductivity

Thermal conductivity measurements were obtained through the

services of the Dow Thermal Research Laboratory. Their method

utilizes a hot-wire transient technique which is reported to have

excellent precision and accuracy (Ref. 8). Verification of their

method and apparatus is based on thermal conductivity

measurements of standard fluids (toluene, diphenyl ether). Good

agreement with literature data (Ref. 9) confirmed the technique

for liquids. The complete report is contained in Appendix III.

16
Thermal conductivity data are summarized in Figure 22 for the

Task II fluids. The dependence of thermal conductivity on

temperature follows the equations:

(MePh) A(V7/m-K) = 0.1237 + 1.5858 x lO"1* T - 3.66 x 10~7 T2 (15)

(Me2) X(W/m-K) = 0.1904 - 8.023 x 10~5 T - 1.54 x 10~7 T2 (16)

Over the years, a number of investigators skilled in thermal

measurements have reported thermal conductivity data on low

viscosity PDMS fluids. These data are summarized in Figure 23.

It is evident that although numerous laboratories show reasonable

precision in their results, accurate thermal conductivity

measurements remain elusive. Uncertainties of ±15% are inherent

in these data at the present time.

Electrical Conductivity

Silicones are excellent electrical insulators. A considerable

number of silicone-based products are applied in electrically

demanding applications based on their dielectric properties.

Volume resistivity for each fluid over a range of temperatures

was measured according to CTM 0272 (Appendix II) . The test

procedure is based on ASTM D-1169.

The data are summarized in Figure 24. The values reported for

the Task II fluids are somewhat lower than values typically

obtained for these types of materials. Volume resistivity

measurements on dielectric materials are subject to some

variability generally attributed to trace levels of contaminants

arising from residual catalysts, absorbed/adsorbed water, and

silanol (SiOH) sites on the fluid.

Manufacturing procedures typically used for dielectric-grade

fluids would provide materials with significantly higher volume

resistivity.

Pour Point

Pour points for the two Task II fluids were measured according to

CTM 0133 (Appendix II) and reported to be less than 188K (-85°C)

for the Me2 fluid and 240K (-33°C) for the MePh fluid. The

values are typical for these types of fluids.

.Polymeric liquids are especially susceptible to supercooling

effects and this is typically observed with silicone fluids. In

view of this characteristic, pour point.data must be viewed with

caution when used to infer flow properties at low temperatures.

This is of concern only with the MePh fluid since the melting

point of the Me2 fluid [233K (-50°C) ] is well below the lowest

temperature anticipated in this application.

17
Flash Point (Pensky-Martin Closed Cup)

Closed-cup flash points were measured according to CTM 0021A

(Appendix II) which is based on ASTM D93. The flash points were

572K (570°F) and 544K (520°F) for the Mea and MePh fluids,

respectively.

Fire Point

Fire points were measured according to CTM 0052 (Appendix II)

which is based on ASTM D-92. In this test, the fluids were

heated to temperatures of 616K (650°F) and 603K (625°F) for the

Me2 and MePh fluids, respectively, with no evidence of a

sustained flame. Measurements at higher temperatures are not

recommended since significant fluid decomposition may occur. The

exceptionally high fire points recorded for the Task II fluids

are expected in view of the low volatility of these fluids.

Viscosity - Temperature

Kinematic viscosities as a function of temperature were measured

as described previously in the Task I phase of this effort. Data

for the Task II fluids are summarized in Table VII and Figure 25,

together with the data for their Task I counterparts.

The Task II Me2 fluid has a slightly lower viscosity than the

Task I sample. This finding is consistent with both GPC and

vapor pressure data which indicate the molecular weight of the

Task II fluid slightly lower.

The viscosity of MePh (Task II) is in good agreement with its

counterpart in Task I except at the lowest temperature (-18°C),

where higher viscosity was noted for the Task II fluid.

Viscosity - Shear Dependence

The viscosity - shear dependence of the Task II fluids was

investigated by Savant, Inc., Midland Michigan. The complete

report from Savant, Inc., together with descriptive literature on

the Tapered Bearing Simulator Viscosimeter (TBS) is included in

Appendix III. .

Several techniques and apparatus were required to provide

measurements over the range of temperatures, viscosities, shear

stress and shear rates of interest. Some methods, [Scanning

Brookfield Viscometer Technique (SET) and Ubbelohde Suspended

Level Capillary Viscometer (USLCV)], utilized conventional

viscometric equipment with minor adaptations, while others,

[Tapered Bearing Simulator Viscometer (TBS), and Cold

18
Cranking Simulator (CCS)] were either developed or adapted in the

Savant Laboratory. A standard calibration fluid (S-3, available

from Cannon Instrument Company) was used to calibrate the

instruments.

The combination of methods available in this facility provided a

special capability for characterization of the shear dependence

of these fluids. Results are summarized in Table VIII.

A major objective in these measurements was to learn whether the

fluids show non-Newtonian behavior. With the Me2 fluid, shear

rates as high as 600,000 sec"1 were achieved with no discernible

reduction in fluid viscosity. These findings are in agreement

with those reported by Ito and Shishido (Ref. 10) in which somewhat higher shear rates were realized with no viscosity reduction

for polydimethylsiloxane fluids of similar viscosity. For the

MePh fluid at low temperatures (268 to 258K) with shear stresses

of 105 N/mf (106 dynes/cm2) and shear rates ranging from 140 to

62,000 sec *, a slight non-Newtonian behavior was observed. At

higher temperatures (423K) and shear rates of 106 sec"1, no

evidence of non-Newtonian behavior was noted.

Vapor Pressure

Vapor pressure data were obtained using the same procedure as in

Task I. Mass loss rates for the Me2 (II) fluid are summarized in

Table IX. Loss rates for Me2 (II) and Me2 (I) are plotted in

Figure 26. It is evident from the first rates measured for each

fluid (Series 1, low temperatures), that the Me2 (II) fluid is

somewhat more volatile than its counterpart in Task I. This is

consistent with results of characterizations by GPC, which show

that Me2 (II) fluid, as distilled, includes species of lower

molecular weight than does Me2 (I) (2450 vs. 2700) .

GPC analyses (Figure 27) also show virtually identical molecular

weight distribution for Me2 (I), as distilled, and Me2 (II) fluid

at the completion of its mass loss, measurements. Again,

characterization by GPC is consistent with evaporation rates,

which are nearly alike for these two samples.

Mass loss rates for MePh (II) are given in Table IX. In Figure

28, loss rates for MePh (II) and MePh (I) are plotted as a

function of temperature. LC data are given in Figure 18. The

significant concentrations of several lower molecular weight

components result .in significantly higher loss rates for MePh

(II) . These findings demonstrate the need for care in the

removal of low molecular weight species in the distillation

procedures necessary to obtain these fluids.

19
Mass loss rate data for each Task II fluid were fitted to

equation (7) using least squares.

Me, Task II

(Series 2)

MePh (Task II)

(Series 2)

log,n m = 14.086 - 10108 (Corr. Coeff. = 0.9989)

'10 (6 data points)

logln m = 12.186 - 8523 (Corr. Coeff. = 1.0000)

T (5 data points)

Using the same data treatment as in Task I, these results were

converted to vapor pressure curves using equations (6) and (8).

The resulting vapor pressures along with those from Task I are

given in Figures 29 and 30 for the Me2 and MePh fluids.

The vapor pressure for the Task II fluids are given by:

Me2 (II) Fluid:

MePh (II) Fluid:

Iog10 P = 16.7247 - 10087

log..n.P = 14.8254 - 8502

10

 ~T~

(17)

(18)

Vapor pressures for the Task II fluids were found to be higher

than was intended in selecting conditions for isolating the

fluids. The effect of distilling a further 20-30% is shown by

comparing the mass loss rates of the fluids as distilled (Series

1), against those after test (Series 2). Vapor pressures at or

below 10

 7 Pa at 394K can be achieved in fluid fractions only

slightly heavier than the Task I and II samples. The GPC and LC

results discussed above show that these methods can provide

control for isolating required fractions.

Heat of Vaporization, Temperature for P = 1.3 x 10

 6 Pa

(10-8 torr)

Using the vapor pressure relationships, Equations 17 and 18, the

tempera_ture at which the fluid's vapor pressure equals 1.3 x 10~6

Pa (10~8 torr) was calculated. The heat of vaporization was

calculated using the Clausius-Clapeyron equation. These

parameters are summarized in Table X.

20
Emittance and Transmittance

A detailed report on the radiative characteristics of the two

Task II fluids is included in Appendix III. All measurements

were performed with a Nicolet 60SX Fourier-Transform infrared

spectrophotometer. The methodology follows that of Kember, et.

al. (Ref. 11). Software provided by the instrument manufacturer

facilitated the subtraction of background spectra and calculation

of fluid emittance, i.e. ratioing the radiant flux of the sample

fluid to that of a blackbody under identical conditions.

Emissivity data for the two Task II fluids are given in Figures

31 and 32. Both materials approximate the emittance of a

blackbody over the range of 5.6 to 25 microns. Flux from both

samples in this range slightly exceeded that from the powdered

graphite reference used, presumably because emittance of the

graphite was less than 1.0. Because of detector limitations,

emissivity measurements were limited to the 3 to 25 micron range.

A relatively minor portion of the energy is radiated between 25

and 55 microns.

Transmittance data for the Task II fluids between 2.5 and 25

microns are given in Figures 33a, b, c. Data at fluid thicknesses of 0.2 mm and 0.02 mm were obtained at room temperature.

For the latter thickness, spectra were run as 20% (w/v) solutions

in 0.1 mm cells. Carbon tetrachloride was used for dilution

between 2.5 and 7.25 microns; carbon bisulfide was used from 7.25

to 25 microns. Both fluids exhibit similar transmission

characteristics. Figures 33d and 33e show the transmittance of

0.01 and O.lmm films, respectively, in the far infrared (20 to

100 microns).

Thermal Stability, Oxidative Stability, Stability Against

Radiation, and Operating Lifetime

The experimental activities reported above relate to the two

critical areas of flow and evaporation and to properties

affecting heat transfer in the LDR application. The third

critical concern is the ability of the working fluid to. retain

its properties in service. Viscosity, mass loss by evaporation

of reaction products, contamination of surfaces by volatile

condensibles and heat transfer properties must be controlled.

The working fluid of the LDR at an altitude of 500 km will be

exposed to an environment involving high vacuum (10

 6 Pa), solar

ultraviolet photon radiation, atomic oxygen at a particle density

of 107/cm3, and energetic protons, electrons, and neutrons.

(Ref. 12). The velocity of the liquid droplets in orbit will

result in approximately 5 eV collisions with the oxygen atoms

(O[3p]). The threshold energy for ionizing chemical bonds is on

the same order. The energetic encounters will increase the

already high reactivity of atomic oxygen.

21
There is a rich background of research describing the effects of

the several components of the LDR environment, excepting atomic

oxygen, on the polymer families of the candidate siloxane fluids.

Splitting of the Si-C bond is discussed at length by Chvalovsky

(Ref 12, 520 references.) Baney reviewed the literature through

1967 on thermal and oxidative reactions (R.H. Baney, "Thermal and

Oxidative Behavior of Silicones", Dow Corning publication, 1967,

113 references).

In an effort to locate data closely applicable to selection or

development of fluids for the LDR, a new search was made of the

Dow Corning Technical Document Data Base, consisting of over

100,000 citations on organosilicon compounds. Focusing on

thermal and oxidative reactions of siloxanes and on the effects

of radiation, some 200 references from the published literature

and a similar number of internal reports were listed. Abstracts

were reviewed. While there is a great deal of useful information

on mechanisms and kinetics of reactions, no prediction of

lifetime for fluids in the LDR application is possible within the

scope of this work. The scarcity of information on reactions of

atomic oxygen with siloxanes precludes prediction, especially

with the combined effects of energetic collisions, vacuum, and UV

photons.

A sampling of the effects of the key environmental factors on

polysiloxanes is given below, to suggest directions for selection

or further development of LDR fluids. An intensive synthesis

from this background literature could add rough quantitative

guidance. The bibliography of published work described above can

be made available for such an effort.

Thermal Effects

Thermal reactions of polydimethylsiloxanes and polymethylphenylsiloxanes below 523-573K in the absence of air, moisture, or

catalysts are negligible in relation to required service life.

Extensive information available on reaction mechanisms may be

useful, however, for predicting effects in the LDR environment.

PDMS and PMPS behave quite differently in that the first reaction

evident in PDMS is rearrangement of siloxane bonds, while for

PMPS, crosslinking through cleavage of SiC or CH bonds dominates.

Siloxane rearrangement predominates for PDMS to 673K or above..

Volatile cyclosiloxanes result, and the molecular weight

distribution of the linear nonvolatile portion broadens. The

activation energy for siloxane rearrangement has been measured

most commonly at about 42 kcal/mol, well below the SiO bond

strength (108 kcal/mol). Ions and silanol are common but

controllable species that greatly accelerate siloxane

rearrangement. Oxygen at only 0.02-0.03% in the inert gas

blanket is highly catalytic, perhaps through production of -SiOH.

This effect is believed to have been present in preparing the Me2

fluid for Task II, at 623K. Even the effects of the typical ions

22
and silanol are probably insignificant at 394K. The silmethylene

(-SiCH2Si-) bond provides a way to strengthen the polymer chain

against formation of cyclics. The activation energy for

silmethylene is reported to approach the bond strength for SiC.

Thermal crosslinking of PMPS also is unimportant at 394K. DC 704

gelled in 400 hours at 673K. But the rate of reaction

(disappearance of the parent 704 molecule) at 623K was only

0.003% per hour (R. Halm, A. Huntress, unpublished work) . Gel

times and viscosity of higher molecular weight polymer can be

expected to respond more strongly to crosslinking than do those

of 704, but on the same order. There are indications that

crosslinking may be less in a Me2-Ph2 configuration than in MePh

having like proportions of Me and Ph ligands. Silphenylene/

siloxane polymers have also been studied extensively, but usually

in elastomeric compositions, and with crystalline alignment of

the silphenylene groups as an objective.

A number of agents have been described that inhibit siloxane

rearrangement, perhaps only for the case of catalyzed reactions.

Various metals (Zr, Fe, Hf, Ce, Ti, B, P, Cu, Co) are reported,

usually introduced as alkoxy, acetylacetonate, acetate, or other

carboxylic acid salt. The SiH group has been found effective in

PDMS, in conjunction with metal additive. These additives are

often more effective for PDMS than for PMPS.

Oxidative Effects

Oxidation in conventional environments causes both depolymerization to cyclosiloxanes and crosslinking. Formaldehyde is the

principal gaseous product, even in PMPS. Phenyl groups reduce

crosslinking rates appreciably, through their greater stability

and by protecting the Me group. It has been reported that a

small amount of phenyl relative to Me is optimum, although

specific circumstances may have produced this result.

Formaldehyde from oxidation of PDMS in air becomes detectable by

423K. Activation energy for the oxidation of PDMS has been

reported as 30 kcal/mol. The exotherm began at 513K in one set

of DTA measurements. The presence of methylphenyl groups raised

the exotherm to 548K for 7 mol percent MePh, and to 573K for 100

mol percent MePh (unpublished work). As in the thermal case,

there are instances where performance of the Ph2 group is found

to be better than that of the MePh group.

Rates of oxidation measured as a function of film thickness have

been interpreted as showing autocatalytic effects, particularly

in relation to volatiles produced. . Reactive species were

believed to be removed by evaporation, so -that thinner films

reacted more slowly. In other work, crosslinked resinous films

appeared on metal surface at 363-373K and grew to a • limit of

about 100 nanometers in 5-6 days (Ref., 14).

23
There has been extensive work on the effects of antioxidants in

siloxanes. Gas evolution, gel times, viscoelastic properties,

and intrinsic viscosity are most often followed. Many of the

same metal salts reported for thermal stabilization are effective

against oxidative reactions. Heat treatments to incorporate the

metal atom into the siloxane chain are frequently employed.

Polymers containing the heteroatoms are synthesized directly with

the same effect. In PDMS, gel times at 573K and above are

extended by from 30 to 500 times. In the DTA work noted above,

Ce and Fe salts both raised the temperature of the exotherm 95K

above that of the untreated PDMS, and 35K above that of PMPS.

Inhibiting effects are generally not as pronounced for PMPS, but

are observed. A partial listing of antioxidants other than the

metal salts follows. Many of these are recognized free radical

scavengers in organic chemistry:

Ferrocene compounds

Phenyl-alpha-naphthylamine

Tricarbonyl Chromium

Mn cyclopentadienyltricarbonyl

Diethylamine

Anthracene; 1,2-benzanthracene

Pyrene

Fluoranthene

Beta,beta1dinaphthyl-p-phenylenediamine

Reactions of atomic oxygen with SiH^ and Me3SiH were reported

(Ref. 15, 16, 17). No references to atomic oxygen with PDMS or

PMPS were found. Heicklen (Ref. 18) has assembled reaction rate

coefficients for 0{3p) in organic reactions. Rate coefficients

are as much as a million times those for 02. The reactivity of

O(3p) with CH4 is less than 10~5 that with nC^Hnj. This

difference may suggest the magnitude of the possible advantage

for PDMS or PMPS over organic polymers, but it also emphasizes

the futility of estimating effects without careful

experimentation.

Effects of Radiation

The effects of energetic radiation on PDMS, PMPS, and other

polysiloxanes have been studied extensively. Rittenhouse and

Singletary (Ref. 12) reviewed space- related effects.

Approximately 60 citations were highlighted in the present

search. Studies include exposures to electrons, protons,

neutrons, and gamma, ultraviolet, and laser radiation.

The principal effect of radiation is crosslinking through the

formation of -SiSi-, -SiCH2Si- or -SiCH2CH2Si-, accompanied by

release of CKi+ and H2. Ions and free radicals are intermediates,

as in organic radiation.chemistry. Radiation in air produces

unstable silicon-based peroxides and hydroperoxides which are,

like radicals, detectable only at reduced temperature. Siloxane

rearrangement is also reported in radiation chemistry.

24
Radiation induced reactions are capable of producing siloxane

species smaller than the parent polymer. In gamma-radiation of

DC 704, at a dose of several hundred megarads, the amounts of

more volatile species formed was not detrimental to continued

performance of the fluid in a diffusion pump.

Increase in the viscosity of PDMS fluids is seen with a radiation

dose on the order of 10° J/kg. The viscosity of 50-100 cs PDMS

may be doubled by a dose of 100 megarads. (For a relatively low

molecular-weight polymer, doubling viscosity requires

approximately one crosslink per two polymer chains, doubling

molecular weight.) Hence, for a given dose (a given number of

crosslinks) the viscosity of shorter chains will rise less than

that of long chains.

Phenyl side groups or phenylene linkages in the polymer backbone

improve the radiation resistance over PDMS. Rates of gas

formation for PDMS are about 100 times those for PMPS. CHi+ and

H2 remain the principal gaseous products. The -Ph2SiO- group is

seen to be more effective than -MePhSiO- against both gamma

radiation and protons.

Much work with ultraviolet radiation has been focused on thermal

control coatings and the absorption of ultraviolet wavelengths.

With ultraviolet the absorption bands of the phenyl group are

detrimental. Aromatic impurities also are said to promote

degradation of PDMS under ultraviolet exposure. Other workers

report less gassing with phenyl present.

Stabilizers have been applied successfully to retard reactions

under radiation. Again, free radical scavengers are favored.

For illustration, di-tertbutyl-p-cresol, quinone, and 4-tertbutylanthraquinone are reported favorably against electrons;

agents against gamma include copper phthalocyanine, n-butylmercaptan, acenaphthene, diphenylselenide, and heteroatoms (B, P,

Ti) in the polymer chain.

Flammability

The unique low vapor pressures of the Me2 and MePh fluid

fractions isolated as candidates for the LDR assures that

combustible vapor mixtures cannot occur except by thermal or

oxidative degradation. The lower limit of combustible concentrations in air or oxygen involves a vapor partial pressure on the

order of 100 Pascals or more. Distillation temperature for these

fluids was approximately 573K at 13 Pascals. Temperature higher

than this would be required to produce a partial pressure of the

parent species in the combustible range.

*

Combustion can occur with the application of sufficient heat to

cause degradation, and under conditions allowing accumulation of

the degradation products. Significant degradation begins in air

25
above 523-573K. Spontaneous ignition temperature for low

molecular weight siloxane products of degradation vary with

composition and conditions, but should not be less than 650K.

Combustion of low-volatility PDMS in pools tends to be self

extinguishing because of the formation of a coating composed of

silica and gel over the surface.

Background on the flammability characteristics of polysiloxanes

will be found in References 19, 20, 21, and 22.

Tgxicity

The two polysiloxane families represented by the LDR fluids are

recognized as showing a very low order of toxicity, based on all

testing reported. PDMS species larger than 8-10 mer units are

not absorbed from the intestinal tract. Smaller species that are

absorbed and metabolized show no toxic effects, in acute or long

term oral studies. PDMS is approved for use in contact with

foods and is a component in antacids where doses of 40-500 mg/day

are typical. There is no absorption through the skin and no

irritation. Direct contact with the eye may cause temporary

conjunctival redness. References 23, 24, and 25 illustrate test

results. Acute effects of PMPS (Dow Corning 710 Fluid) are

summarized in Appendix IV.

26
TASK III. FURTHER DEVELOPMENT OF FLUIDS

The means for preparing fluids of the necessary low vapor

pressure for the LDR has been demonstrated with the siloxane

polymers isolated. Some further development of the vacuum strip

process will be required to refine control, and possibly to

produce moderately heavier fluid, with still lower vapor

pressure. The viscosities of the fluids recovered are reasonable. Several directions might be taken to further reduce

viscosity:

The copolymer Me2/MePh might replace MePh fluid if the full

stabilizing effect of the phenyl ligand is not required.

Structural effects on the viscosity of methylphenyl

siloxanes can be explored. Me2/MePh copolymer endblocked

with MePh2 may duplicate the vapor pressure and Me/Ph ratio

of MePh fluid, with moderately lower viscosity.

Chemical routes exist by which either MePh or Me2 fluid can

be made nearly monodisperse. Eliminating the higher

molecular weight members will reduce viscosity, especially

for MePh fluid.

Further activity with respect to fluid lifetime probably should

await more definite understanding of the effect of the unusual

environment at the altitude of the Space Station. Both testing

in the simulated environment and detailed study of known reaction

mechanisms and kinetics will be needed. Stabilization may be

useful either through additives, as discussed briefly above, or

through altered polymers. Some alternative polymers include:

Polydimethyldiphenylsiloxane. Several studies show

stability superior to methylphenyl structure.

Silmethylenesiloxane. Siloxane rearrangement is reduced by

substituting (-SiCH2Si-) for some of the siloxane bonds in

the polymer backbone.

Silazane (-SiNHSi-) in the MePh siloxane chain is reported

to resist proton radiation.

Siloxanes with metal atoms along the chain, as frequently

described in literature.

Fluorinated siloxanes or fluorocarbon siloxanes. Special

resistance to atomic oxygen is suggested in a concurrent

program for structural coatings for the Space Station.

27
CONCLUDING REMARKS

Siloxane fluids combining the low vapor pressure and low viscosity

needed in a working fluid for the Liquid Droplet Radiator have

been identified and characterized. Lighter fractions of these

fluids may optimize viscosity for operation in the lower end of

the anticipated temperature range. Service lifetime in the unique

combined environment of the LDR probably cannot be predicted from

available data. Stabilizers or modified polymers probably can

extend lifetime if greater stability is found to be necessary.

28
REFERENCES

1. Presler, A.F., Coles, C.E., Diem-Kirsop, P.S., White, K.A.,

NASA Technical Memorandum 87139, (1985).

2. Elaine, R.L., Industrial Research, March, 1976.

3. Wiedemann, H.G., Thermochim. Acta, 3^ 355 (1972).

4. Carter, O.L., Dupont Thermal Analysis Applications Brief

TA-34.

5. Ashcroft, S. J. , Thermochim. Acta., 2_, 512 (1971).

6. Wilhelmy, L., Ann. Physik. 119, 177 (1863).

7. Alexander, A.E., in "Physical Methods of Organic Chemistry",

by A. Weissberger, ed., 3rd ed., p. 732 (1959), Interscience,

N.Y.

8. DeGroot, J.J., et al., Physica 75, 454 (1974).

9. Ziebland, H. and Burton, J. , J. Chem. Eng. Data, ^(4), 579

(1961).

10. Ito, Y. and Shishido, S., J. Poly. Sci., 1Q_, 2239 (1972).

11. Kember, D., et al., Spectrochim. Acta., 35A, 455 (1979).

12. Rittenhouse, J.B., Singletary, J.B., Space Materials Handbook,

3rd Ed., AFML-TR-68-205 (1968).

13. Chvalovsky, V., "Cleavage Reactions of the Carbon-Silicon

Bond", (Becker, E.I., Tsutsui, M., Ed.), Organometallic

Reactions, Vol. 3, Wiley-Interscience, p. 191-317 (1972).

14. Willis, R. , Shaw, R. , J. Colloid Interface Sci., _3_1 (3) , 397

(1969).

15. Kharvtunyan, S.A., Mkryan, T.G., Sarkisyan, E.N. , Oxid.

Commun. , ]_(l-2) , 49-56 (1984).

16. Mkyran, T.G., Sarkisyan, E.N., Arutyunyan, S.A., (Russ),

Armenian Chemical Journal, ^_4(1), 3 (1981).

17. Hoffmeyer, H., Horie, 0., Potzinger, P., Reimann, B.,

J. Phys. Chem., £2(13), 2901-2905 (1985).

18. Heicklen, J., Atmospheric Chemistry, Academic Press (1976).

19. Lipowitz, J. , J. Fire Flammability, 1_, 482 (1976).

20. Lipowitz, J., J. Fire Flammability, 1_, 504 (1976).

29
REFERENCES (continued)

21. Solbrig, C.W. , Jamison, W.E., J. of Vac. Sci. & Tech., 11(5),

228-233 (1965).

22. Reuther, H., Reichel, G., Chem. Tech. (Leipzig), L7(12), 752

(1965).

23. Rowe, V.K., Spencer, H.C., Bass, S.L., J. Ind. Hyg. &

Toxicol., W(6), 332-362 (1948).

24. Calandra, J.C., Keplinger, M.L., Hobbs, E.J., Tyler, L.J.,

ACS Polymer Preprint, r7(l) , 12 (1976).

25. Frye, C.L. , Soap, Cosmetics, Chemical Specialties, j5£(8), 32

(1983).

30
TABLE I

SCREENING CANDIDATE FLUIDS

Dow Corning

Reference

6138-42-2 Me3

6758-8C Ph2

6758-10B Me3

6758-12C Me3

6758-13B Me3

SiO(MePhSiO)

Fluid

SiMe.

n

 3

MeSiO(Me.SiO 2 ) (MePhSiO) SiMePh,

 n m z

SiO(Me.SiO)

• n

SiO(Me.SiO 2 )

 n

SiO(Me.SiO 2 )

 n

Initial Strip

Conditions (T/P)

Pot

MePh 638

Ph2Me 631

Me2/MePh 653

Me2 653

HexMe/ 653

Vapor

575/26

605/12

601/26

624/26

625/114

(MePhSiO) SiMe,

m

 3

SiMe3

(HexMeSiO) SiMe,

m

 J

Topping Strip

Conditions (T/P)

Pot Vapor

583 548/10

580 553/10

589 578/12

604 582/18

590 575/12

Source

Bottoms from Developmental

Fluid (also present in Dow

Corning® 710 Fluid)

Bottoms from Dow Corning 704®

Dow Corning® 550 Fluid

Dow Corning® 200 Fluid/20 cst

Developmental Fluid

Ref. 6513-62-4

Weight Percent in Fractions

Volatiles LDR Cut Bottoms

66 17 15

73 11 11

22 5.6 71

64 13 21

41 10 47

Me.

31
TABLE II

MOLECULAR WEIGHTS BY GPC

TASK I FLUIDS

Fluid M M

w

Dispersity Index

Ph2Me

MePh

Me2/MePh

Me2 .

HexMe/Me.

1180

1240

1690

2670

2500

1390

1280

1770

2720

2700

1.17

1.03

1.05

1.02

1.08

32
TABLE III

VISCOSITY

TASK I FLUIDS

Kinematic Viscosity [m2/sec]

Fluid 255K(0°F/-18°C) 297K(75°F/24°C) 339K(150°F/66°C) 394K(250°F/121°C)

Ph2Me

MePh

Me2/MePh

Me2

HexMe/Me2

1574 x

6450 x

567.7 x

76.3 x

116.8 x

10~6

10~6

10'6

10~6

10~6

91

145

64

28

34

.8 x

.4 x

.6 x

.8 x

.2 x

10~6

io"6

10~6

10~6

10~6

27

31

21

14

15

.4 x 10"

.9 x 10~

.8 x 10~

.49 x 10

.53 x 10

6

6

6

~6

-6

9.

10

8.

7.

7.

92 x

.4 x

74 x

20 x

35 x

10~6

10~6

10~6

10'6

10~6

1. v(centistokes) = v[m2/sec] x 10e

33
TABLE IV

TGA - EVAPORATIVE MASS LOSS DATA

TASK I

Fluid

704

(0.45 Torr)

T(K)

Mass Loss Rate

[kg/m2-sec] (Minutes)

704

(0.75 Torr)

MePh

(0.45 Torr)

Ph2Me

(0.45 Torr)

Run 1

Ph2Me

(0.45 Torr)

Run 2

361

371

380

392

402

413

365

375

386

397

433

445

456

476

497

507

467

517

527

466

545

536

525

515

506

496

486

478

448

458

466

478

487

497

507.5

1.43000E-06

3.46000E-06

9.91000E-06

0.0000232

0.0000591

0.000112

1.35000E-06

4.15000E-06

1.04000E-05

0.0000233

1.72000E-07

3.81000E-07

7.54000E-07

2.68000E-06

1.14000E-05

0.0000182

1.31500E-06

0.000028

0.0000494

2.31000E-07

0.0000243

0.0000178 " "

1.18000E-05

7.95000E-06

5.17000E-06

3.55000E-06

2.29000E-06

1.82000E-06

3.25000E-07

5.38000E-07

9.60000E-07

1.74000E-06

2.77000E-06

4.71000E-06

8.08000E-06

0.002766

0.002693

0.002631

0.002550

0.00249

0.002420

0.002735

0.002662

0.002590

0.00252

0.002313

0.002246

0.002190

0.002097

0.002016

0.001971

0.002143

0.001936

0.001900

0.002143

0.001834

0.001866 '

0.001900

0.001944

0.001980

0.002016

0.002057

0.002088

0.002227

0.002180

0.002145

0.002092

0.002053

0.002012

0.001970

900

300

150

100

60

60

540

240

150

90

720

540

360

360

120

60

60

60

30

180

60

60

120

120

360

360

540

720

900

900

720

480

360

240

120

34
TABLE IV (continued)

Fluid

Me2/MePh

(0.45 Torr)

Me2

(0.45 Torr)

KexMe/Me2

(0.45 Torr)

Ph2Me

(0.45 Torr)

Run 3

T(K)

447

458

468

486

497

508

458

468

478

447

458

468

479

488

498

508

458

468

479

420

433

445

453

463

483

493

433

443

453

463

437

446.

458

468

478

488

507 .

438

446

458

468

478

Mass Loss Rate

[kg/m2-sec]

9.05000E-08

1.81600E-07

4.01000E-07

1.63900E-06

3.04000E-06

5.67000E-06

5.44600E-08

1.45400E-07

3.78000E-07

2.21500E-08

7.11000E-08

2.79000E-07

7.40600E-07

1.15400E-06

2.73000E-06

4.86500E-06

3.78500E-08

1.03100E-07

2.98000E-07

1.24600E-08

2.95400E-08

9.05000E-08

2.10000E-07

4.98000E-07

2.98000E-06

6.45000E-06

1.75000E-08

4.34000E-08

1.14000E-07

2.95000E-07

1.93000E-07

2.48000E-07

4.99000E-07

1.26000E-06

2.17000E-06

3.54000E-06

1.06000E-05

1.66000E-08

4.62000E-08,

1.22000E-07

3.18000E-07

7.85000E-07

1/T(K)

0.002237

0.002180

0.002134

0.002057

0.002012

0.001968

0.002183

0.002137

0.002092

0.002237 '

0.002180

0.002137

0.002087

0.002049

0.002007

0.001968

0.002183

0.002137

0.002087

0.002381

0.002309

0.002246

0.002207

0.002159

0.002070

0.002028

0.002309

0.002257

0.002207

0.002159

0.002288

0.002242

0.002183

0.002137

0.002092

0.002049

0.001972

0.002283

0.002242

0.002183

0.002137

0.002092

Time

(Minutes)

900

900

720

360

240

120

900

720

360

900

900

720

480

360

240

120

900

720

480

900

900

720

720

360

120

120

360

240 .

200

120

720

720

480

360

180

180

120

720

720

480

360

150

35
TABLE IV (continued)

Fluid

704

(Calculated)

(Knudsen eq'n)

T(K)

298

373

473

572

675

423

323

348

394

Mass Loss Rate

[kg/m2-sec]

1.74000E-08

0.000155

0.192

13.34

199.9

0.00892 '

6.43000E-07

1.22000E-05

0.000983

1/T (K)

0.0033524

0.0026832

0.002116

0.0017472

0.0014822

0.0023619

0.0030913

0.0028729

0.0025401

Time

(Minutes)

36
TABLE V

DENSITY

TASK II FLUIDS

(Me2 Fluid)

Temperature K(°C)

293

298

303

313

323

333

343,

(20

(25

(30

(40

(50

2 (60

3 (70

0)

0)

0)

0)

0)

.2)

.3)

Density

kg/m3

960.9

956.4

951.8

943.2

934.2

925.1

916.2

p(kg/m3) = 1221-0.8878T

(MePh Fluid)

Temperature K(°C)

293

298

303

313

323

333.

343,

(20

(25

(30

(40,

(50

0)

0)

0)

0)

0)

(60.2)

(70.3)

Density

kg/m3

1085.0

1081.0

1077.3

1069.7

1061.8

1053.8

1046.2

p(kg/m3) = 1311-0.7723T

p(g/cm3) = p(kg/m3) x 10'

37
TABLE VI

SURFACE TENSION

TASK II FLUIDS

Temperature

K(°C)

MePh

295 (22.0 )

295.1

301.5

305.0

308.0

310.0

313.0

315.5

323.0

329.7

334.4

347.5

366.0

373.0

Y =

293.7

301.5

304.0

309.5

314.0

319.0

323.0

326.0

332.0

336.5

340.0

352.0

357.0

363.0

367.0

Y =

(22.1)

(28.5)

(32.0 )

(35.0)

(37.0 )

(40.0 )

(42.5 )

(50.0 )

(56.7)

(61.4)

(74.5 )

(93.0 )

(100.0)

0.0411

(20.7 )

(28.5 )

(31.0)

(36.5 )

(41.0)

(46.0 )

(50.-0)

(53.0)

(59.0)

(63.5)

(67.0 )

(79.0 )

(84.0 )

(88.0)

(92.0 )

0.0397

Surface Tension

N/m

0.0205

0.0206

0.0202

0.0200

0.0198

0.0196

0.0194

0.0191

0.0188

0.0181

0.0180

0.0171

0.0156

0.0152

- 6.9 x 10

0.0240

0.0236

0.0236

0.0232

0.0228

0.0226

0.0223

0.0222

0.0219

0.0216

0.0215

0.0208

0.0205

0.0204

0.0202

- 5.3 x 10

1. Y (dynes/cm) = y (N/m) x 103

38
TABLE VII

KINEMATIC VISCOSITY VS. TEMPERATURE

TASK I & TASK II FLUIDS

Kinematic Viscosity (m2/sec.)

Fluid 255K (0°F/-18C) 297K (75°F/24C) 339K (150°F/66C) 394K (250°F/121C)

MePh

Task II 1438.0 x 10~5 14.8 x 10~5 2.96 x 10~5

Task I 645.0 x 10~5 14.54 x 10~5 3.19 x 10~5 1.04 x 10~5

Task II

Task I

6.76 x 10~5

7.63 x 10~5

2.54 x 10~5

2.88 x 10~5

1.29 x 10~5

1.449 x 10~5 .720 x 10~5

1. v(centistokes) = v(m2/sec) x 106

39
TABLE VIII

VISCOSITY-SHEAR DATA

TASK II FLUIDS

Device/

Technique

Brookfield

CCS

USLCV

TBS

°C

Temp

-40

-40

150

150

Shear Stress,

Dyne/Sq . Cm .

1,000

1,000,000

10

40,000

Viscosity, cP

Low Temp. High Temp. Ratio

Me, Fluid

158

165 0.96

4.02

4.13 0.97

(sec'1) 3

Shear Rate

633

606,000

249

969,000

MePh Fluid

Brookfield

CCS

Brookfield

CCS

Brookfield

CCS

USLCV

TBS

1 . Savant ,

2. Ratio =

-5

-5

-10

-10

-15

-15

150

"150

Inc.

2,370

1,000,000

4,840

1,000,000

4,540

1,000,000

25

65 ,000

, Midland, Michigan

1700

1610 1.06

3230

2940 1.10

6820

6200 1.10

6.34

6.49 0.98

139

62,100

150

34,000

66.6

16,100

394

1,000,000

Low shear dynamic viscosity /m J J ^

High shear dynamic viscosity

3. Shear rate (sec. *) = Shear stress

Dynamic viscosity

40
TABLE IX

TGA - EVAPORATIVE MASS LOSS DATA

TASK II FLUIDS

MePh

T(K)

448

458

465

470

479

489

499

508

460

470

479

489

463

417

426

436

446

455

465

426

436

446

455

Mass Loss Rate

(kg/m3-sec) 1/T(K)

1.35000E-07

3.23000E-07

6.14000E-07

8.72000E-07

1.65000E-06

4.43000E-06

6.12000E-06

0.0000172

1.37000E-07

3.78000E-07

8.86000E-07

2.53000E-06

1.20000E-05

1.72000E-07

3.97000E-07

9.32000E-07

1.61000E-06

4.34000E-06

8.58000E-06

1.63000E-07

4.48000E-07

1.07000E-06

2.36000E-06

0.002232

0.002183

0.002151

0.002128

0.002088

0.002045

0.002004

0.001969

0.002174

0.002128

0.002088

0.002045

0.00216

0.002398

0.002347

0.002294

0.002242

0.002198

0.002151

0.002347

0.002294

0.002242

0.002198

Time (Minutes)

720

720

360

360

240

180

60

60

540

360

360

120

120

420

• 420

240

240 •

90

90

420

240

240

90

41
TABLE X

HEAT OF VAPORIZATION & TEMPERATURE (P = 1.3 x 10 ° Pa)

TASK II FLUIDS

Vapor Pressure Parameters

Fluid

Me2

MePh

A .

16.7247

14.8254

_B

-10087

-8502

AHv(J/mole)

(cal./g mole)

195,000 (46,600)

165,000 (39,400)

T[K]

408

373

P

v

 =

42
lE+8b

1E*83

1E+82

iE+ii

en 1E-S1

% 1E-I2

cn

Ck£

.1E-85

IHb

1E-S9

P(iorr)=

)C184

1-11

• n

,811

P(to

?TAfCET

-258

8288-1-18 k'Jb

1808/T(K)

Figure 1. Vapor Pressure of DC 704, DC 705

43
5-

4-

CD

HH

LU

CLJ

1E+03;

7-

5-

4-

3-

X

H PolymethyIphenyIsi loxane

x Po I yd i methyls i loxane

18 19 20 21 22 23 24 25 2b

Retention Time CM i nates)

27 28

FIGURE 2. GPC Calibration

44
en

0)

•H

o

<D

a

O)

Oi

•<-\

4-1

3

n-l

H

U

cn M-I

s o

o

cu c

LO O

W -H

a; 4-1

<o

« n

O 4-1

H c

u <u

w u

EH C

W O

Q U

O

4-1

Number-Average MW = 1686

Weight-Average MW = 1773

Polydispersity Index

Peak Apex MW = 1689

M

w

^—n

= 1.05

Proportion

a

-T l-l 1

H >- •

J <I '

III T =

I.I T 1

-:T -. C =~^-

i

I 1 1 —J 1

t. i>4 U'l i.'J '.'J Ul

— V.I If O t: IVI

u, t n i ivi i-i

UJ

i. U M M « T I D N

I

• '.'-1

i.tUJ

H

J

UJ

I.M

•:I

UJ

1 '

OJ U+

•(• •:>

i

t

t

1=

(LOG MW VflLUES PRINTED EVERY 2 MINUTES

FIGURE 3. GPC Chromatogram of Me2/Me[7'

h ~

45
<u

O M

•H C

s a i S

.c o

Q. ^J

0

> 0)

I 4->

D <U

Q

—V

MePh - (I)

t?

TIME

^e

0)

o w

•H C

a) tao

e a) 0«

0 M

,C O

01 4->

> 0)

o a>

Q

Ph2Me - (I)

12

Tine

16 24

Higher Mol. Wt.

FIGURE 4.

\

Reverse-Phase Liquid Chromatographic Analysis of MePh - (I)

and Ph2Me - (J)

46
1E-02

50 260 270 280 290 300 310 320 330 340 350 360 370 380 390

TEMPERATURE (K)

FIGURE 5. Kinematic Viscosity of Task I Fluids

47
0

i-l

a

w

w

- 0 -

•TJ

^o
'a

w

o

<O

-

3

O

•H

e

o

o

en

5 o

^ 0

1-1

 "31

•a

•H

3

T Ou

S i

cs

u

hH

Cu

49
Ij-l

4

2

IF- ill

it Vi

A ' 4

n

; .

L

1F-01?- iL Vi

.4-

9.

£

IF- (3"? 1C ISO4- 4

0

i."

1F-04 ll_ ST-

|.

T

9

1

IF-il L tl d

4-

9.

L

1F-flfi iL «ud4 -

9.

i.

1F-1H 1L - \il 1

4!

4

'?.

i

IF-flfl

0

X

*

7i4 (MLCULATED)

7i4 U5Torr)

7i4 (.75Torr)

/

//

..

/

//

//

/

// r / /

0

/

/.

//

/

//'

/

c>

Jll/

7

//

//

/

i

x //

x

• f

: \

/

•

 /X

*/ / V

-(2!

o

/

//

/

!F)

/

/ /

//

/

_ --

<&

y

/

//

/

-

y

/// //

f

• --

Ui i2 2,80 2,b0 2,48 2,21 2,0

FIGURE 8. Mass" Loss Rate Data of 704 Reference Fluid

a) Calculated-Knudsen Equation

b) Measured (0.45 Torr and 0.75 Torr)

50
iL

1E-I

LJJ

u-i

I

Cr>

•-^

C3D '

1E-87

~IL

'84 USTorr)

-1

2,9«2,8i2,?H2,bn,5«2,48 2,38 2,282,112,881,981,88

FIGURE 9. Measurements of Mass Loss Rates - Repeatability

51
i.

1E-84

• b

4

2

1E-85

b

9. £

1F-flf» 1 L IS 0-

hu-

/I

9.

1F-H7 1C W 1-

fi.

IJ4H-

'?.

i

1F-flft

o 7@4 USTorr)

* H92/HePh-i

x HQ2/M

-_ - - — —

.nu n Qrtl'Z

0

>

__ _

A!

. ._ ..:._ .

^ -

0

/byi-

- /

./..

./

i

/

1/

/

/

/

1

/I

// i

f

-

1,91 2, Si 2,78 2, b8.2,58 2,4S 2,39 2,28 2,18 2,881,98 1,3

FIGURE lOa. Mass Loss Rates for Me /MePh - (I)

52
IE-!

iE-85

b

•1E-86-

lE-i?

1E-1.

MF

181 2,312,8S 2, ?i 2, bi 2,59 2,41 2,38 2,2i 2,182, if 1,9i 1.5

/T(K)

FIGURE lOb. Mass Loss Rates for Me2 - (I)

53
1E1E-95

•

lE-i?

o;

(,45Torr)

* HexHe/JM-1

III 2,9i2.8n.7i2.b82,5n,4i2,3i2,2i2,in,i8i,9n,:

FIGURE lOc. Mass Loss Rates for HexMe/Me2 - (I)

54
1E-84

IE-!

>iH

1E-87-

*

r

i.80 2,98 2.88 2,7(12,bi 2,58 2.4i 2,38 2.282,182,881,981,8

188B/T(K)

FIGURE lOd. Mass Loss Rates for MePh - (I)

55
CJ

cu

2

1E-14

b

4

2

b

4

2

4.

»1F-flfi 3

 1 L 11 Ubu4.

/J

IEIF-fl? . 4' f-

(l-

'J

4.

.*t

v.

lE~i8

•

X

.,

A

•

.

x;

}

X

m

1

x 7i4 USTorr)

* Ph2HQ(Run*3)-l

- Ph2fte(Runt3)-2

,

%

1

-'-•1

J

1I

*

/

/ /

V/

X

/

_

.

y

/

V

/

•tf

f

- -• . -. -

4U

 Til 2,91 2,31 2,1 2.bi 2,51 2,41 2,31 2,21 2,11 2,11 1,1 '1,38

56

FIGURE lOe. Mass Loss Rates for Ph2Me - (I)
1E+81

1H1

1F-8 1L 8li 9.

CD

iEcn J

S 1E-85

Qci

iE-8b

[HI

3:

1E-18

HQ2/hQPh(l)

(2)

m-

•'"!2,98 2,88 2,78 2,b8 2,5 8 2,48 2,3 8 2,2 8 2,18 2,8 8 1,98

1888/TOO

FIGURE lla. Vapor Pressure of Me2/MePh (1), Me2/MePh (2)

57
7

(

.J

lE+fl!

7

•J

iE-il

7

0

1E-92

7- j

. IE- 83

o-i

^r 7"

e 5 J

cn

-<n j r A i g lE-84=

Cfc' 7-

' 1 cn -

J

^ IE-IS.

t ] \

^ lE-8bL

J

1E-8?S

?:

"

..1E-88-

7!

•j

lE-@3=

7:

j

• 1F-KIL — ca-.

— -- _jir--r- ---

— m

Ho? f 1 )

HP/ i ?

/

€

/

•

.1-11 ii , . ii

— ^-/

/

-J—

,

V

/

Jrnr

uBr

y

/

/

/

.

y X ^ y

l' /

/

-

y*^ /

f

 //

*/

s /

'/

-fi

/

/—

2,88 2.78 2,b8 2,58 2,41 2.38 2,28 2.18 2,88 i.

1888/NK)

58

FIGURE lib. Vapor Pressure of Me2 (1), Me2 (2)
1Fn

£:

%-*j

glE-(

en J

3 IE-IS

j

7

1E-87;

1E-I

1E-18-

.-3e-HQxMQ/MQ2(l)

H9xHe/He2 (5

2,91 2,8i 2,?@ 2,b8 2,5i 2,48 2JS 2,28 2,11 2,88 1,98

FIGURE lie. Vapor Pressure of HexMe/Me2 (1), HexMe/Me2 (2)

59
1E-31

1E-82

„ iE-83»

en

en

Q_

'—'

iE-85

I

1E1E-18

--HQPh(l)

2,98 2,88 2,78 2,b8 2,58 2,48 2.38 111 2,18 2.88 l,9i

FIGURE lid. Vapor Pressure of MePh (1), MePh (2)

60
en

S

Qci

1E-85

- 3

lE-ib

]

1E-87

]

IE-IS

1E-89;

1Ez

2,1 2,8i 2,78 2,b8 2,58 2,4 8 2,38 2.2S 2,11 2,8 8 1,98

FIGURE lie. Vapor Pressure of Ph2Me (1), Ph2Me (2)

61
lE+ii

3

3

1E-81

o

7

en

-=o;

en

lE-8b

1E-87

.. J

1E-88

1E-89:

IE-:

Ph2Ho(2)

--HQxH9/M92(2)

H9Ph(2)

He? (2)

2.98 2,81 2,78 2,b8 2,58 2,48 2.38 2,28 2,11 2,89 1,98

62

FIGURE 12. Vapor Pressures of Task I Fluids
m 320 348

Temperature ,

FIGURE 13. Working Temperature Ranges, Task I Fluids

Range bars terminate at viscosity of

25 x 10 m2/sec (low temperature) and

10~^ Pa (high temperature)

No working range exists for 704

63
!• I

S—S—2-3-S-S-?--=

ORIGINAL PAGE ES

POOR QUALrTY

TD

•H

<N

0)

4-1

O

t-l

-P

O

73

0)

S-l

<0

H

IH

C

o:

64
I [MM i rrfrm-tf

ID

•r-l

D

I

E

H

4J

O

01

a

UJ

D

O

H

Cn

65
onCNX(N

la-

id

CN

0)

•HCOC

N

TJOJ 24Jo0)atoKs2I

cn

WOS3

(I)

•ii OIIe

6 6j
.C04<Ds•H

TD

•H3

(NX

o(0M-PQ0)Atn II la zi enCN

Cfl cu •Hoit2 COCO

67
5.08 6.15 7.38 8.45 9.60 10.75 11.90 13.05 14.20 15.35 16.50

RETENTION TIME (MINUTES)

OJ

cj- tn

•H c

V4 O

4J ft

oj en

e cu

O 03

4J

o ^

J= O

On ±J

0

> a)

a a)

a

MePh - (I)

it ! ;u \ * >-j

 J

1 4 I n

T IMF: i M INI.ITE ;/

FIGURE 18. Reverse-Phase Liquid Chromatograms of MePh (I and II) Fluid

6,8
ORIGINAL PAGE IS

OF POOR QUALITY

1,110-3

310 320 330

TEMPERATURE CK)

350 3b0

FIGURE 19. Density of Task II Fluids

69
I i 1 I I I 1 1 ! II J I I I ! I I (I I I I

280 290 300 310 320 330 340 350 360' 370 38(

TEMPERATURE (K)

FIGURE 20. Surface Tension of Task II Fluids

70
1.8-50

TEMPERATURE (K)

FIGURE 21. Heat Capacity of Task II Fluids

71
"250 270 290 ' 310 330 ' 35i 37i 390

.TEMPERATURE (K)

410 430 450

FIGURE 22. Thermal Conductivity of Task II Fluids

72
0.160

0.15©

0.140

0.120

0.110

CfcLi 0.100

r

0.090

0J

-JjTI

i b'

hT

iL

Privat e

0 L1

b-0

j-n

i

t-1/1 h . . i i

Communications

2-DfNATECH

ftJrt ! \'}Q.\ Hid I

(i.St.Uiii v

d.St.Uni v

1-LDR-HQ2CII)

ep loenQiy y

stofPe^

-btfe

I ! 1

troi

X

250

-Dow Therma l Lab.

t Karm

. -Pub.

8@-63 (197

4-012

cr

"S:

I ! I til l

350 • 400 450 •

TEMPERATURE (K)

500 550

FIGURE 23. Thermal Conductivity of PDMS Fluids

73
25-

r-i

T-H

CL

X

OJ

20-

-k. = vo lime conduct i v i uy

v i tvj

£

o

E15 -

\

10-

\ MePHCII)

Me2(II)

LJJ

Oi

5-

28© 290 300 310 320 330'340 350 360 370 380 390 400 410 420

TEMPERATURE (K)

FIGURE 24. Volume Resistivity of Task II Fluids

74
IEOJ

IEen

IE1E1E-0

250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400

TEMPERATURE (K)

FIGURE 25. Kinematic Viscosity of Task (I and II) Fluids

75
LT!

I

i.

1E-84-

>j

7

j1E-85-

5

3-

i.

1R1h 1- L « v j

Fj

J

7

9.

1F-87 1L V \ -

fj.

j

7

.j"

•IT- p.

a MQ2QD-1

- H92(II)-2

• Hg2(I)-l

• M92(IH

i

i i i ,

"

M

/

f

1

1

S3

/

^

/

n / } /

° ^/ A/

///

/ /

an;/

/

/

/

//

1

/i

ll

ll i

l\f\

'

l

nl

a /

//

/

/

i

I//

j

4

 3.88 2,98 2.88 2,1 2,b 8 2,51 2,4 8 2,38 2,28 2,18 2,88 1,38 1,:

1888/KK)

FIGURE 26. Mass Loss Rates for Me2 (II) and Me2 (I)

76
w

w

o

W

os

o

E-i

U

w

EHa

Q

Me, (II)

y

14 .8 14 .4 14.8

TIME: I.

16.4

FIGURE 27. GPC Analysis Me2 (I) Before Mass Loss Measurements

(II) After Mass Loss Measurementc

77
1E-MOJ

LT!

iE-86±=

5

1E-87:

HePluIIH

HeFhiHH

•- 1 11 t X .' A

1 -2

•/

i2L

//

£

i.ii 2,9i 2.88-2.78 2.b8 2,51 2.48 2.38 2.28 2.18 IU 1,33 1.38

FIGURE 28. Mass Loss Rates for MePh (II) and MePh (I)

78
ORIGINAL PAGE IS

OF POOR QUALITY

1E*81

2,1 2,88 2,78 2,b« 2,58 2,48 2,38 111 2,19 Z,@8 US

1888/T(K)

FIGURE 29. Vapor Pressure of Me (II) and Me (I)

79
iEnn

2,98 - 2,88 2,"78 2,bfl 2,51 MS 2,38 2,2 8 2,18 2,8 8 1,98

1888/T(K)

FIGURE 30. Vapor Pressure of MePh (II) and MePh (I)

80
ao

CJ LOh- <EaoCDN£uc_JCDaaOJo

t—H

f-

<E

CC

Oo

-CD

TD

•H3

,—1

fcl

-00

O2'l DO

T

08

090

o-om

81
LJIDQOCDU^<E_l GDOaLUa<EQC

921

82

801 06*

81
o

01

l/l

<n

a

m -

in

a

20X SOI.UTIPN

0.1 MM GEL

Me2 (II)

4000 3600 -v:no 2Qoo a-too aooo isoo 1200 aoo

uiflVENUMBERS

too

4000 3600 3<200 2800 2fOO 20OO 1600 1200 800 .400

WflVENUMBERS '

FIGURE 33a. Transmission Spectra of Task II Fluids in a

20% Solution in a O.lmm Cell

83
SOI
SOI 0
5OO "tSO tOO 350 300 £50 ZO" ISO

WflVENUMBERS (cm'1)

100

500 ' tSO -,00 350 ' 300 '25O 200 Tso 100

WflVENUMBERS (cm"1)

FIGURE 33d. Transmission Spectra of 0.01mm Films of Fluids

in the far IR Region.

86
500 450 >tOO 350 300 Z50 TTO!.1

 i 50 100

WftVENUMBERS (cm"1)

o i

500 tSO tG3 35O 300 ZSO i 200

WflVENUMBERS (cm -

1-)

I SO 100

Figure 33e. Transmission Spectra of O.lmm Films of Fluids

in the far IR Region.
APPENDIX I

TARGET VAPOR PRESSURE FOR LDR FLUID
APPENDIX I

TARGET VAPOR PRESSURE FOR LDR FLUID

An estimate is made of the vapor pressure of an LDR fluid that

results in mass loss by evaporation from droplets of 10% per

year.

Assumed:

Drop diameter, d = 0.01 cm

Fraction of fluid charge exposed as droplets at all times = 10%

Temperature of droplets = 394K (250°F)

Molecular weight, M = 1000

Evaporation follows Knudsen (no correction here for surface

tension or curvature of small drop):

Then m = A PV /"M^2 (I - I)

17.14

Where: m = mass loss rate, gm/sec

A = area of evaporating surface = ird2

P = vapor pressure, torr

M = molecular weight

Fractional loss rates, F = m (1-2)

m

m = Vp (1-3)

Where: V = volume of drop, ird3/6

P = density of fluid ^ 1 gm/cm3

Combining equations 1, 2, and 3, fractional loss per year (for

10% of charge exposed) is:

F = 1.76 x 10~8 PV

For 10% loss per year (F = 0.1)

-10

or 7.5 x 10~8 Pascal.

PV = 5.6 x 10

 1U torr
APPENDIX II

DOW CORNING CTM'S AND EQUIPMENT LITERATURE
APPENDIX II

This appendix includes the Dow Corning Test Methods (CTM's) and

equipment literature relevant to the physical property

measurements reported herein.

Liquid Chromatograph (GPC)

Liquid Chromatograph (Reverse-Phase)

Kinematic Viscosity [CTM-0004]

951 Thermogravimetric Analyzer

Mettler Paar Digital Density Meter

Specific Heat - 910 Differential Scanning Calorimeter

FT-IR Spectrophotometer

Pour Point [CTM-0133]

Flash Point [CTM-0021A]

Fire Point [CTM-0052]

Volume Resistivity [CTM-0272]
Liquid Chromatograph - GPC

Pump: Perkin-Elmer Series 4

Column Set: TSK Gel Type H: 1 x 64000H, 1 x 62500H,

1 x 62000H

Injection Volume: 50 microliters

Detector: ERMA Differential Refractometer

Mobile Phase: Tetrahydrofuran (uninhibited)

Liquid Chromatograph - Reverse Phase

Pump: Perkin-Elmer Series 4

Column: Shandon C-18 4.6 x 100 mm 3 ym particles

Injection Volume: 10 yl, 0.7% solution

Detector: Waters Model 490 U-V, 260 nm

Gradient Conditions:

Sector Time

equil

1

2

3

4

5

12

10

10

6

3

5

Flow Rate

ml/min.

1

1

1

2

2

1

H20

30

0

0

0

30

30

*Tetrahydrofuran, uninhibited

**Acetonitrile, HPLC grade

THF*

40

40

40

40

40

40

ACN**

30

60

60

60

30

30

Gradient

Shape

linear

step
DOW CORNING

corporate test method

VISCOSITY - Glass Capillary Viscometer

July 29, 1970 CTM 0004

Abstract

The kinematic viscosity of liquids is determined by measuring the time required for a fixed volume of samples to pass

through a calibrated glass capillary using "gravity-flow".

The method is based on ASTM D-445, IP 71 and the results are

reported in Stokes. A calculation for determining the

absolute viscosity (dynamic viscosity) in Poise is given

(Note 1).

Apparatus

Bath: Constant temperature to hold 25 ± 0.2°C. Any

suitable source.

Viscometer: A set of one of the following types (Note 2) to

cover the desired range of viscosities.

1. Cannon Fenski: Fisher Scientific Co., Pittsburgh,

PA, Cat. No. 13-616.

2. Ostwald: Fisher Scientific Co., Cat. No. 13-695.

3. Ubbelohde: Fisher Scientific Co., Cat. No. 13-614.

Reagents

Primary standard fluids: Various viscosities, Cannon

Instrument Co., State College, PA.

Secondary standard fluids: Appropriate viscosity silicone

oil standardized using calibrated master viscometers (ASTM

D-2162).

Precautions

Safety: Normal safe laboratory practices.

Procedural: No unusual precautions.

Page 1 of 4

The miiihcxl described has been adapted f rum either our investigations or literature proceditrosoi l»oth The Dow Cor mm) Curpuiniioiidous not .ibsunuany liability in connection with the use o( this method Applicability to samples ot interest nuisi be ascertained by the user This method should nu:

)>e reproduced or published in whole or part without written permission ol the Dow CornnH) Corporation

DOW CORNING CORPORATION, MIDLAND, MICHIGAN 48640 TELEPHONE 517 496-4000
CTM 0004 2

Parameters

Viscosities may be determined at temperatures other than

25°C. Results will be in Stokes or centistokes unless

otherwise requested.

Procedure

Select a clean, dry calibrated viscometer that will yield a

flow time of greater than 80 sec with the sample. Load the

viscometer in the correct manner as dictated by the design

(Note 3). Place the tube in the constant temperature bath

and allow it to reach equilibrium (at least 15 min. at

25°C). Use suction or pressure (Note 4) to adjust the head

level of the sample to a point about 5 mm above the first

timing mark. Allow the sample to flow freely. Start a

timer as the meniscus passes the first timing mark. Stop

the timer as the meniscus passes the second timing mark.

Record the time to the nearest 0.1 sec. Repeat the test

without refilling the tube. If the two results do not agree

to within 0.2 sec, repeat the procedure with a new sample.

Use the average in calculating the viscosity. Report

viscosity and temperature.

S tandardi z ati on

Viscometers should be calibrated and given an identification

mark upon receipt and then calibrated at least once every

year or whenever cleaned with strong acid or base or after

being repaired. Either primary or secondary standards may

be used.

Follow the procedure and determine the flow time. Calculate

the viscometer factor:

_ Viscosity of Standard _ Stokes*

flow time, sec sec

* Centistokes may be used if preferred where:

1 St = 100 cSt

Viscometers should be thoroughly cleaned with appropriate

cleaning mixtures. Viscometers used with silicone fluids

should be retained exclusively for that purpose. They may

require cleaning with hydrofluoric acid.

Calculations

Kinematic viscosity:

Viscosity, St* = F x flow time, sec

* Centistokes if preferred.
CTM 0004 3

Absolute viscosity:

Viscosity P* = (kinematic viscosity, St) (density g/cm3)

* CentiPoise if preferred.

Precision and Accuracy

The relative error should be less than ±1% (Note 5).

Notes

1. In cgs units, viscosity is expressed in the following

dimensions:

a. Stokes - cm2/sec

b. Poise - g/cm/sec

2. The Ubbelohde viscometers are the preferred unit. They

cover the range of 0.4 to 100,000 cSt. They are easy

to fill and are free falling column viscometers.

The Cannon Fenski viscometers have one advantage. They

require a smaller sample size. However, they require

an exact fill. They cover the range of 0.4 to 16,000

cSt. Any of these viscometers may be used interchangeably, if properly standardized.

The Oswald viscometers are not preferred due to the

extreme self-leveling effect of the fluid flow and

consistent fill requirement. They cover the range of

0.4 to 16,000 cSt.

3. The - Ubbelohde viscometers are filled by pouring the

sample down the largest tube until the bulb is about

3/4 full (the vent tube must be open). The amount is

not critical. The other two must be filled by drawing

the sample in to fill mark or by. adding a specific

volume.

4. Care must be taken in handling volatile samples.

5. A "quick and dirty" viscosity measurement with a

precision of ± 5% or better can be obtained using a

calibrated volumetric pipet on as little as 1 ml of

sample and following this basic procedure.
CTM 0004

References

1. ASTM D-445

2. ASTM D-2162

3. ASTM D-2515

4. Institute of Petroleum 71/66

Figures, Graphs and Sketches

None

Ed. Corr.

7/81

JEW

10:T
951 TGA Thermogravimetrlc Analyzer

Operator's Manual

ORIGINAL PAGE IS

OF POOR QUALITY
Thermal Analyzers 951 T6A

Introduction

ORIGINAL PAGE IS

OF POOR QUALITY

Section 1. INTRODUCTION

1-1. PURPOSE OF MANUAL

This manual contains information necessary to

understand, install, operate, maintain, and order

parts for the Du Pont 951 Thermogravimetric

Analyzer (figure 1 -1). This section of the manual

provides component description, principles of

operation, and specifications.

1-2. INSTRUMENT FUNCTION

The 951 Thermogravimetric Analyzer (TGA) is

a plug-in module for Du Pont Thermal Analyzers. It constantly measures the amount and

rate of weight change of material, either as a

function of increasing temperature, or isothermally as a function of time, in a varied but controlled atmosphere. The TGA can be interfaced

with other analytical instruments (such as a

gas chromatograph or a mass spectrometer)

for multiple measurements. Also, the TGA can

be readily modified or isolated for special applications.

1-3. DESCRIPTION (figure 1-2)

The TGA consists of three major sections: a

furnace assembly, a balance assembly, and a

cabinet assembly.

Figure 1-1. 951 Thermogravimetric Analyzer

1-1
951 ISA

Introduction

Thermal Analyzers

FURNACE TUBE

RETAINING RING

O-RING

(TEFLON)

QUARTZ

FURNACE

TUBE

SAMPLE

PAN

COLD QUARTZ

BEAM SHROUD

O-RING

(SILICONE)

RIBBON CABLE

CONNECTOR

SAMPLE

THERMOCOUPLE

•TAUT-BAND

METER MOVEMENT

•REAR BALANCE

BEAM

COUNTERWEIGHT

ARM

COUNTERWEIGHT

O-RING

FURNACE

ASSEMBLY

SHUTTER

PHOTODIOOES

HORIZONTAL

SUPPORT RODS

BALANCE

ASSEMBLY ^ PYREX ENVELOPE

STOP

•PART OF SHUTTER ASSEMBLY

BALANCE

ASSEMBLY

LEVELING FEET

CABINET

7/74C

9S1K/I

•s

Figure 1-2. 951 TGA Location of Components

1-2
Thermal Analyzers

. 951 T8A

Introduction

0

a. Furnace Assembly

The furnace assembly is a 500-W, resistancewound plug-in unit of low thermal mass that

can be heated and cooled rapidly. (Heating rates

up to 100°C/min. can be obtained to an upper

limit of 1000°C). A Platinel II control thermocouple, in the furnace wall, monitors furnace

temperature. For rapid work involving consecutive analyses, two furnaces can be used alternately. The furnace can be rapidly cooled by a

fan within the cabinet assembly.

b. Balance Assembly

The balance assembly consists of a balance

housing, a control chamber, and a sample

chamber. Mounted within the balance housing

is a taut-band meter movement to which a

balance beam is attached. The ends of this

beam extend into the sample and control

chambers. The control chamber contains a

shutter assembly and a counterweight arm,

mounted on the beam, and a beam stop pin; a

lamp and photodiodes are mounted on a member extending from the balance housing. A

Pyrex® envelope, held in place by two thumbscrew retainers and sealed by a silicone 0-ring,

encloses the control chamber. The sample

chamber contains a quartz rod, which is attached to the beam, a sample pan suspended from

the rod, and a sample thermocouple. A quartz

furnace tube, held in place by a retaining ring

and sealed by two 0-rings, encloses the sample

chamber. Both aluminum and platinum sample

pans are available. Platinum pans are recommended for use above 500°C. Pyrex furnace

tubes are available for operation below 500°C.

The balance assembly rides on horizontal

support rods. This permits movement of the

balance assembly for sample loading. A stop on

one support rod positions the assembly so that

the sample is in the center of the furnace.

Purge gas is admitted through a hose fitting on

the rear of the balance housing, and exits

through the opening in the furnace tube. Electrical connections to the balance assembly are

made through a connector on the rear of the

balance housing.

Nine weights are provided for counterbalancing

the sample pan and for calibrating the instrument.

Quantity

1

2

2

1

1

1

1

c. Cabinet Assembly

Weight

5 mg

10 mg

20 mg

50 mg

100 mg

200 mg

50 mg (Precision)

The cabinet assembly houses the balance control and associated electronic circuits and the

cooling fan. Adjustment and calibration controls, an accessory connector, and a fuse are on

the rear. Operator controls are on the front.

Leveling feet are provided for leveling the unit

in its operating position.

1-4. PRINCIPLES OF OPERATION

(figure 1-3)

The 951 TGA operates on a null-balance principle. Physically attached to a taut-band meter

movement, the balance beam is maintained in

a horizontal reference position by an optically

actuated servo loop. Attached to the control end

of the balance beam is a light shutter; a constant

intensity lamp is focused through an aperture

slit in the shutter to strike two vertically

mounted photodiodes. When the balance beam

is in a null position, the focused light strikes both

photodiodes equally. As sample weight is lost

or gained, however, the beam becomes unbalanced and moves from the null position,

causing more light to strike one photodiode

than the other. The voltage output from the

photodiode receiving the most light increases

and unbalances the photodiode amplifier, producing a current flow in the taut-band meter

which acts as a restoring force on the balance

beam, driving it back to its null position. The

magnitude of the restoring current flow is

directly proportional to the sample weight lost

1-3
991 T6A

Introduction

Thermal Analyzers

PHOTOOIODES

TAUT-BAND METER

MOVEMENT

PHOTOOIOOE

AMP

THERMOCOUPLE

COMPENSATION

THERMOCOUPLE

PROGRAMMER COMPENSATION

SUPPRESSION

CALIBRATION

COMPRESSION

X-Y RECORDER

A/79C

9ft1«/4

Figure 1-3. 951 TCA Block Diagram

1-4
Thermal Analyzers 951 ISA

Introduction

(or gained). After being conditioned, the restoring current is displayed on the vertical axes

of an X-Y recorder as either absolute sample

weight loss/gain or weight percent loss/gain;

the format is pre-selectable by the operator.

Balance and suppression controls are provided

for adjusting the meter movement drive current.

Small differences in weight (less than 5 mg)

during initial nulling of an empty balance are

compensated with the balance circuit. Fixed

current offsets equivalent to weight (mass) are

accomplished with the suppression circuit. A

coarse control provides 10 steps of 10 mg each

for a total of 100 mg. A fine control, consisting

of a 10-turn potentiometer, provides 1 mg for

each turn. Thus the combination of both coarse

and fine controls allows for a total electronic

weight suppression of 110 mg. For suppression

above 110 mg, mechanical tare procedures

are used by placing weights on the counterweight arm in the control chamber.

sample. The thermocouple output is electronically compensated and then displayed on the

recorder.

During heating, the sample may undergo

changes which liberate gases. To prevent these

gases from back-diffusing and condensing

on the meter movement, purge gas is admitted

into the balance housing. The purge gas flows

over the meter movement, fills the control

chamber, and purges the sample chamber by

exiting through the end of the furnace tube.

The heating rate and temperature of the furnace

are set by the programmer. The control thermocouple in the furnace provides the necessary

temperature information to the programmer

for temperature control.

1-5. SPECIFICATIONS

A lime Constant Circuit filters (Smooths) the •Capacity SOOmg including sample pan

output signal to compensate for minor ambient • Wei«

hl Ranses

 °C0

20

 » 20 mo/cm <o.oso to

. . . ._.... , 5 0 mg/m.)

v.brat.on. It can be adjusted in four steps . Temperature Range: Ambient to , 2000C

ranging from zero (no filtering) to 5 seconds

(maximum filtering). .Suppression 110 mg electronic tare.

..... . . stepped an d continuously

A SCale Compression (attenuation) Circuit pro- variable; mechanical tare to

vides for the adjustment of the Y'-axis output soo mg

signal to the recorder. In the off position of the • Suppression Accuracy ±0.4% of supression

control, there is no compression of the signal

and the full output signal is applied to the Y' • ^f8'

0

"?l « « ,. ,

.... . . . . . . Weight Measurement 0.4% offull scale

axis. When the control is rotated clockwise, a

potentiometer is placed in the circuit which . Accuracy of

compresses the output signal. Full scale read- weight Measurement ± i .0% of MI scale

ings on the recorder may then be calibrated in

. .. . • Derivative Range 0.020 to 20 (mg/min)/cm

weight percent. (005.50 (n,g/min,/in.,

A span calibration circuit provides a sensitivity

... . . , . , . ... . . • Time Constant 0 (direct), 1. 2. 5 seconds

adjustment which is used when calibrating the

balance beam. • Pressure Atmosphericlo 10OPa (Itorr)

• Purge Rate Up to 1 2/min

The sample temperature is obtained from the . control Thermocouple piatineiii

Sample thermocouple located Close to the • Sample Thermocouple Chromel-Alumel

1-5/1-6
Mettler

Digital Density Meters

from Mettler/Paar

OR1Q1NAL

OF POOR

Measuring specific gravity, density,

concentration and other density-related values

7/L
Mettler/Paar

Digital Density Mete

ORIGINAL PAGE fS

OE POOR QUALITY

Mettler/Paar Digital Density Meters provide a fast, accurate means of measuring

densities or specific gravities of liquids

and gases, as well as concentration of

solutions. Highly accurate results are obtained in seconds without the need for

skilled technicians. And without timeconsuming procedures such as pycnometer filling, waiting for temperature

equilibrium, weighing. There's no need to

determine weight, volume or temperature

of samples — thereby eliminating inherent

sources of error.

Wide range of applications

Fields of application range from both

pure and clinical research to quality

assurance and process control. Mettler/ •

Paar Digital Density. Meters are ideally

suited for identification, characterization

and purity of measurements. They are

also used for concentration measurements

(Brix, Plato, Balling, API, etc.), for determining densities of physiological fluids

(protein content of serum, density of

blood on continuous flow or single

sample base), for the study of enzymes,,

proteins, polymerizations and macromolecules. These instruments are in wide

use throughout the pharmaceutical,

cosmetic, petrochemical, food, beverage

and general chemical industries. There are

also numerous research applications in

universities and hospitals. Other uses are

found in government (ERDA) and police

laboratories.

A unique measuring method

The heart of each Density Meter is a

U-shaped, oscillating sample tube. In

operation, this tube is completely filled

with 0.7 ml of sample substance by injection with a hypodermic syringe, with a

pump, with vacuum suction or by continuous flow. The sample tube is electromagnetically excited. Density, specific

gravity, or concentration of the sample

is determined precisely by the measurement of the period of oscillation of the

sample tube'. Accuracy is not affected

by the liquid's viscosity, volatility and

surface tension. As long as the sample is

liquid or pasty enough to be injected and

withdrawn, it can be measured.

This measuring method is most accurate

and its versatility allows the study of

many samples which cannot be measured

precisely any other way.

Direct digital data

Most of the Mettler/Paar density instruments are equipped with a built-in microcomputer, for direct display, in large

digital numerals, of density, specific

gravity, concentration or other densityrelated values such as Brix, Plato, Balling,

API, etc. Some instruments have a builtin electronic Peltier-effect thermostat (no

cooling water required). Some read a

digital period value for external calculation of the density. Digital data then can

be transmitted to a printer or computer

for data storage or evaluation. Analog

output signals, available in some instruments, can be used for continuous
ORIGINAL PAGE JS

OF POOR QUALITY

monitoring of density or concentration

changes on flowing samples.

Special capabilities

The usefulness of Mettler/Paar Digital

Density Meters can be greatly extended

through a wide range of accessories. For

example, there are a variety of remote

measuring cells for use at higher and

lower sample temperatures, at high pressures, with 0.1 ml sample volume (instead

of 0.7 ml) or for continuous flow mea-

. surementsJn.hazardous areas and_other

conditions. An automatic sample changer

can be used with the instrument for completely automatic measurement of up to

20 samples.

Chooie the preciiion you need

DMA35 has a precision of 10° g/cm3,

and is a battery-powered hand-held model

for field, production line or lab work.

DMA45 and DMA46 read density, specific gravity or concentration direct with a

precision' of 10' g/cm3 and are ideal for

routine use in quality control or in checking formulation accuracy. The DMA46

comes with a built-in Peltier-effect thermosta'. (no water thermostat required). A

variation, the DMA40, comes without

microcomputer and reads period values

only to be converted to densities by an

outside calculator.

The DMA55, equipped with a microcomputer, has five-place precision' and is

recommended for use where highur accuracy and/or continous flow measurement are required/The measuring time is

selectable between 0.7 and 5.0 seconds.

The microcomputer in the DMA55 can

be supplied with customized programs.

An analog output is also offered. The

zero point of the analog output range can

be set with a TO' 5 g/cm3 precision within

the whole density range and the span can

be selected from 0.001 to 0.5 g/cm3. The

resolution of the analog signal is 0.1 per

cent. Printers and recorders are optional

accessories.

DMA60offers six-place precision3, reads

period values, has analog output for the

two or three least significant digits of the

period value. This unit will work with one

or two DMA602 measuring cells and is

ideally suited for research, for determining new literature values, for absolute

best accuracy and precision. A unique

unconditionally stable, phase-locked loop

frequency multiplier allows the use of the

second DMA602 measuring cell as the

time base in the period measurement.

This results in highest precision due to

minimizing or completely eliminating effects of sample temperature variation.

O. Kratky, H. Leopold, H. Slabmger The determination ol the partial specific volume ol proleins by the mechanical oscillator technique.

In: Hirs. C. H. W.. S. N. Timashefl (Eds)-

Methods in Enzymology, Vol. XXVH. Pan 0.

Academic Press. New York - London 1973.

98-110. and H. Leopold. R. Je/inek, C. P Ti/z:

The application of the mechanical oscillator

technique lor (he determination ol the density

o( physiological fluids. Biomedizmische Techmk.

22 (1977). S. 231-235

Alter correct calibration, accuracy equals precision in a range of 0.5 to I 5 g/cm1

.
:£|ens/i*y Meter Specifications .ORIGINAL PAGE IS

OF POOR QUALITY

Measuring unit*

Model numtM»

Measuring range

Precisian ' J

Sample size (approximately)

.Sample temperature range

Temperature equilibrium

 3

Typ. test or cycling tlma *

Pressure *

Digital display reads

Digital data output

Analog output .

' Required external

thermostat precision

Dimensions

Weight

3-plac* precision

DMA35

0..1 S99g/cm3

±1 x 10-3g/cm3

2.0ml

0-.+40°C

15-60 sees

7psi

choice of true

density, specific

gravity, Brix

has built-in

thermostat

3.7 x 7 x 26.5 cm

550g

4-p<«ce precltlon /r )

OMA40O (

0... 3 g/cm3 x

± 1 x 10'* g/cm3

0.7ml

-IO... + 60'C

O.S...I min

1...5 min

up lo 150 psi

period of

oscillation -T*

5 decades SCO *

±0.05*0

230x300x130 mm

11kg

DM A 43 ^/

•«rr3"g/cm3

± 1 x 10'4 g/cm3

0.7ml

-10... + 60*C

0.5...1mln

1...5min

up to ISO psi

true density,

concentration,

specific gravity

5 decades SCO

±0.05*C

250x300x130 mm

11kg

DMA 40

0... 3 g/cm3

± 1 x 10" g/cm3

0.7ml

+-15...*-38*C

0.5... 3.5 min

1...3min

up to ISO psi

true density,

concentration,

specific gravity

5 decades BCD

has built-in

thermostat

250x425x130 mm

15kg

S-place precision

DMA S3

O...3g/cmj

± 1 x 10"5 g/cm3

0.7ml

-10... + 60*C

0.5... 4 min

2. ..6 min •

up to ISO psi

true density, specific

gravity, concentration

and other parameters

related to density

6 decades BCD*

O...SV'

(tower voltages,

9,g.0...iOOmV.

available on request)

±0.01*0

250x425x260 mm

20kg

0-pl«c» prtcUion

DMA 60/602

0... 3 g/cm3

1.5 x 1Q-« g/cm3 '

0.7ml

-10...-C60-C

1...5min

2 ... 3 min

up to 150 psi

period of

oscillation 'T

8 decades SCO

0...5 V (conversion of 2 or

3 least significant digits of

T-value) ' (lower voltages,

e.g. 0...100mV.

available on request)

±0.01*C

250x425x130 mm. each

6 kg/ 21 kg

' The instruments are to be calibrated with air and a liquid of known density (usually bldlstilled boiled water). The specification refers to a range

of ± 0.5 g/cm3 around calibration point and depends on the thermal coefficient of expansion of sample. If properly calibrated, the accuracy of each

measurement can approach the precision of the instrument.

* If calibrated with air and water, DMA 40, DMA 45 and DMA 46 will show a deviation from true density less than ± 5.10'4 g/cm3 DMA 50 and DMA 60

will show a deviation from true density less than ± 1.10"4 over entire range of 0 to 3 g/cm3.

3

 Depending on desired precision and the thermal preconditioning of the sample.

4

 If applicable sample, changer SP 2 Is used.

1

 Given values apply to standard version. Higher pressure up to 700 psi upon request: up to 6000 psi on special remota cell.

* Optional version excluding digital data output available.

' 210 kQ load; resolution better than 0.1%; for DMA55 only: range from 0.001 to 0.5 g/cm3, selectable in nine steps.

* For continuous Mow a sampling rate from approximately 10 to SO per min. can be selected.

* Best accuracy and precision is achieved when using two remote cells in differential mode.

Type

DMA401*

DMA401W*

OMAS12

DMA602

DMA602T

OMA602H

OMA602M

DMA602W

OMA602HT

DMA602MH

DMA602MW

DMA602HW

Max. precision

(g/cm3)

1x10-*

1x10'4

1x10**

IxlO'4

1.5x10-"

1.5x10"*

1.5 x«T*

1.Sx10~*

ixur5 '

1.5x10'*

1.5 x 10~*

1.5 x 10-"

1 x 10'*

1.5x10-*

1x10'*

1.5 x 10-*

Calibr.

range (g/cm3)

±0.5

±0.5

±0.1

±0.5

±0.5

±0.5

±0.5

±0.01

±0.1

±0.5

±0.5

±0.01

±0.1

±0.01

±0.1

±0.5

Sample

size (ml)

0.7

3.0

1.0

1.0

0.7

0.7

0.7

0.1 (0.3)

0.7

0.7

0.1 (0.3)

0.1 (0.3)

0.7

Temp, range

CC)

- 10 to +• 60

-10 to +-60

- 10 to +• 150

-10 to •(• 150

- 10 to •»• 60

- 200 to > 60

-10 to +150

- 10 to + 60

- 10 to •»• 60

- 200 to + 150

- 10 to +• 150

- 10 to + 60

- 10 to + 150

Normal

press, range

vac. to 150 psi

vac. to 15 psi

vac. to 6000 psi

vac to 6000 psi

vac. to 150 psi

vac. to 150 psi

vac. to ISO psi

vac. to 150 psi

vac. to 15 psi

vac. to ISO psi

vac. to 150 psi

vac. to IS psi

vac. to 15 psi

Dimensions

(mm)

140x380x85

140x380x85

250x425x130

250x425x130

250x425x130

250 x 425 x 130

250 x 425 x 130

250x423x130

250x425x130

250x425x130

250x425x130

250x425x130

Weight

(kg)

10

10

20

21

21

21

21

21

21

21

21

21

Note: The * W designates calls with heat exchanger for continuous now operation. Maximum flow rate Is 6 ml/mln. for temperature difference of ± 5 *C

and expected accuracy of 1 x 10'1 g/cm3 (DMA 602W) and accuracy of 1 x 10** g/cm1 (DMA401W).

The letter *P* placed behind model designation specifies a cell for selected higher pressure range. Up to 700 psi on standard cells, up to ISO psi

on • w ceils. Pressure range for 'MP'.'WHP". as well as 401P 4 401WP cells on request

•Comes wltn Adapter Box 49194. Dimensions are 145x190x63 mm; weight 1kg. -

StrtDKI lo racimcal crt»rvj«i Cooytiqm by M«ii»r Printed n US. A.

Mettler Instalment Corporation. Box 71. Highlstown. N.J. 08520, USA. Tel. (609) 448-3000. Telex 843352

/r- /
Operator's Manual

•?WCd

910

Du Pont Company

Clinical and Instrument Systems Division

Concord Plaza — McKean Building

Wilmington, DE 19893

PN 9;003T-COO. r.av. C

Issuea July 1332

' "^^3 "UR^-I o 1 A-v*-o ^7-7-^-!a.«-»

ii j j 3 iij - j-2 J >ij ^2 j y Z3 j o

Clinical and instrument Systems Division
DSC Cell

OR!Glf4AL PAGE IS

OF POOR QUALITY

The system's measuring unit is a plug-in DSC cell, which is used to measure differential heat flow. In

the cell, the sample and an empty reference pan sit on raised platforms on a constantan disc. Heat is

transferred through the disc to the sample and reference. Differential heat flow is monitored by

thermocouples located beneath the disc.

0

COVES

THERMAL

RADIATION^

SHIELD \

HEATER

RUBBER

0-RING

REFERENCE

PAN SILVER RING

PURGE GAS INLET

HEATING

BLOCK

CONSTANTAN

(THERMOELECTRIC)

DISC

THERMOCOUPLE

JUNCTION

CHROMEL WIRE

HEATING BLOCK

DSC CELL CROSS-SECTION

-^-—V' 'lr' •'•'• ' ' i'x' '\ REFERENCE

DYNAMIC SAMPLE CHAMBER IvXJPAN

^ ^-^ SAMPLE

PLATFORM

CHROMEL

WAFER

FAIRING

PURGE GAS COOLANT VACUUM BASE PLATE

Cross Section, DSC Cell

Pressure DSC Cell

The pressure DSC cell is a DSC cell enclosed in a steel cylinder that can be pressurized to 7 MPa

(1000 psig). This cell has two gas pressure control valves and a pressure gauge on the front; a

pressure relief valve and gas pressure fittings are located on the rear. An 8.3 MPa (1200 psig)

pressure relief valve is contained in the base.
Determining Heat Capacity

To determine the heat capacity of a test specimen, compare the .heat flow difference between

sample and reference under blank and sample conditions as follows:

a. Load empty sample and reference pans.

b. Set the starting and limit temperatures over the temperature range desired.

c. Allow the system to equilibrate for 5 minutes.

d. Position the pen near the top of the chart.

e. Temperature-program the empty pans at an appropriate rate (e.g.. 20°C/min). Deflection from

the initial equilibrium point may be up or down depending on the heat capacity difference

between the pans.

f. Repeat this procedure under identical conditions with a weighed sample in the sample pan. Do

not adjust pen position between blank and sample runs.

g. Calculate heat capacity by measuring the difference in Y-axis displacement (calorimetri^ differential) between the sample and blank curves at any desired temperature. See the following figure.

h. Substitute the difference into the following equation:

[eOEAqsl

Cp

_ feOE Aqsl AY

~|_ Hr J m

EXO

^q

ENDO

Cp =

SAPPHIRE

WEIGHT rtr 61 35 mg

ATMOSPHERE = Nitrogen

HFATING P.ATE = 20'C. mm

60 E Acs

Hr

60 s

mm

sU

J

 m

0.156 mW 20 mV

mV cm

20

 CC

6.80 cm

61.35 mg

• = Cp = 1 04 J/g

SO 100 150 200 250 300 350 400 450 500 550 600

36

TEMPERATURE (°C)

Specific Heat of Sapphire
operation

where E = Cell calibration coefficient at the temperature of interest in

mW/mV (dimensionless)

Aqs = Y-axis RANGE setting in mV/cm (mcal-s'Vin)

Hr = Heating rate in °C/min

AY = Difference in Y-axis deflection between sample and blank curves at

temperature of interest in cm (in)

m = Sample mass in mg (mg)

Cp = Heat capacity in J/g °C (mcai/mg °C)

•MOTES

• The quantity (60E Aqs/Hr) is constant under a given set of experimental conditions.

It converts the AY measurement directly into units of heat capacity in J/g °C (meal/

mg »C).

• For highest accuracy, determine the value of this constant (as an entity) by running a

standard material of known specific heat under identical conditions as the unknown

sample. Then substitute the values of AY. m, and Cp for the standard into the above

equation at the temperature of interest.

• A sapphire (A12O3) standard is provided in the accessory kit for this purpose.

PRESSURE DSC OPERATING PROCEDURES

A safety margin is designed into the pressure DSC cell. Nevertheless, you should pay attention to the

following precautions.

WARNING

Any time the OUT or pressure relief valve is opened during operation, you may be

applying full pressure to the external lines or components (flowmeter. vacuum pump,

etc). These components may not be able to withstand full pressure.

Sample Loading

Do not use tools to open or close the cell. Use the following procedure to prepare the cell for a run:

a. Open the pressure release valve and leave it open to ensure that the cell is at ambient

temperature.

b. Close the IN control valve.

•WARNING

Excessive bolt friction is an almost sure sign that the cell is still under some pressure.

Check the valves.

c. Remove the top plate, cell cover, and silver lid.

d. Load the sample and reference as you would in a normal DSC eel!.

37

•"^'-S^^'^^^^-^/^rJ^,^
Nicolet 60SX: Setting new standards for research-grade FT-IR.

Uncompromising FT-IR

Performance and Versatility

When choosing a research-grade

FT-IR, you shouldn't settle for less than

Nicolet's 60SX. While others make

promises and offer compromises,

Nicolet delivers proven performance

and versatility that no other FT-IR can

match.

Superior spectral quality

and experiment capabilities

In evaluating a research-grade FT-IR,

your first consideration is the quality

of the fundamental spectral data and

the spectrometer's overall

performance. The uncompromising

design of the 60SX interferometer and

electronics provides the ultimate in

speed, sensitivity, and accuracy.

The 60SX meets your most

demanding application needs. Some

of our unique capabilities include:

Fastest spectra in FT-IR! 60SX rapid

scanning (up to 50 scans/second) lets

you study dynamic processes such as

reaction kinetics and catalysis.

Unmatched microsampling

capabilities. The 60SX

computer-controlled microsampling

accessory provides best performance

for:

• Samples as small as 12 microns.

• Surface analysis of small samples

with Nicolet's exclusive micro-ATR.

••• Automated sample positioning and

mapping.

Widest range of experiments

in the least time.

With the 60SX you can solve a

multitude of tough problems rapidly,

accurately, and conveniently. Only

the 60SX provides you with:

• Quick switching from mirco-ATR

to GC-IR to diffuse reflectance to

emittance to micro-transmittance

to LC-IR to photoacoustic IR ... no

other FT-IR can match the versatility

and convenience of the 60SX!

ORIGINAL IS

OF POOR

i; |i!irv

|j,ii'

Micro-ATR measurement of a

small, coated fiber optic sample

shows superb sensitivity.

• Experiment modules let you set up

experiments away from the optical

bench.

• Self-enclosed, pre-aligned detector

modules can be installed in seconds

on any of four detector ports. No

tedious manual alignment, no purge

leaking.

• Computer-selected spectral

coverage from 25,000 to 10 cm'

without breaking

purge.

• Convenient computer-controlled

selection of source, detector port,

spectral range, iris size, mirror

velocity, interferometer alignment.

Fastest, most powerful

computer in FT-IR.

Nicolet's super-minicomputer,

designed for the spectroscopist,

provides exceptional computation

power and speed, outperforming

microcomputer-based systems with

add-on array processors. Further 60SX

computer advantages:

• NICOS real-time operating system

optimized for the laboratory

environment.

• Ease of use through automation and

menu-driven software.

• Comprehensive, field-proven

software.

• External communication to VAXTM,

other computers.

Call or write for full information

on the 60SX — the FT-IR

for scientists

who demand

the best.

Nicolet

The FTSpectroscopy People

Nicolet Analytical Division

5225-1 Verona Road

Madison. WI 5371 1 / 6O8-273-5004

CIRCLE 162 ON READER SERVICE CARD
1.0 6CSX PHYSICAL LAYOUT STSSJ-

 WGE 5S

OF POOR QUALITY

The SOSX is a complete research-grade FT-IR system offering a

resolution of 0.25 cm-1 throughout the standard range of 5000 - 400

cm-1. The system components can be arranged into two main

groups: the data system including the computer, disk drives, and

terminal, and the spectrometer including the optical bench and

master control. See figure 1 for a typical 60SX system

configuration.

1.1 OPTICAL BENCH

The standard optical bench offers a resolution of 0.25 cm-1 ^

throughout the standard range of 5000 - 400 cm-1. The range is

extendable from 25,000 - 10 cm~l with the appropriate combination

of source, beamsplitter, and detector. Applications intensive

options such as automatic beamsplitter changer, computer-aided

alignment, and microbeam are available. Additional software and

hardware features will be released from time to time.

The system includes a continuous scan Michelson interferometer

with maximum retardation of 4.0 cm, variable mirror drive rates,

and a nominal aperture of 2" diameter. A laser reference

interferometer is included for wavelength accuracy. A unique

system for monitoring absolute mirror position during the scan is

also included. The system has the capabilities for multiple detectors

and multiple sources selectable under computer control. Many of

the common bench functions can be controlled through the bench

control panel without the data system. Special firmware for custom

options can be accessed through this panel. Figure 2 shows the

optical layout of the 60SX bench.

1.2 MASTER CONTROL

The master control contains the electronics to control the 60SX

bench. The master control is microprocessor based which allows

flexibility in programming and operation. A number of important

signals are available at the master control for troubleshooting the

svstem.

1.3 POWER SUPPLY

The power supply assembly contains the various DC power supplies

for the SOSX bench. These power the entire bench including the

sources, laser, and electronics. It also indicates the presence of

power to the laser in the system.
\W\\j

Figure 1 TYPICAL 60SX SYSTEM LAYOUT
ORIGINAL PAGE IS

OF POOR QUALITY

Figure 2 60SX OPTICAL BENCH LAYOUT
DOW CORNING

POUR POINT

January 28, 1971 CTM 0133

Abstract

The Pour Point of a liquid is determined by cooling the

material under controlled conditions (Note 1) and observing

the temperature at which the material will not flow when the

container is held at an angle. The primary method uses one

cooling bath and does not comply with ASTM D-97, Compliance

with ASTM D-97 must be specified (Note 2). The results are

reported in degrees Fahrenheit to the nearest five degrees.

Apparatus

Bath: Any suitable container for holding the required

cooling solution and having a support to hold the jacket in

a vertical position (Note 2).

Flask: Dewar, stainless steel, 4 in. (10.2 cm) ID and 7-1/2

in. (17 cm) high. Any suitable source.

Flask: Glass, 1.2 in. (3.1 cm) ID and 5 in. (12.7 cm) high

with a flat bottom. Any suitable source.

Place a mark on the flask 2-1/8 in. (5.4 cm) above the

bottom of the inside.

Jacket: Brass, 1.6 in. (4.1 cm) ID and 4.5 in. (11.5 cm)

high, equipped with a cork disk in the bottom and a support

ring to allow the glass flask to be inserted and moved

-easily but held in a vertical position. Any suitable.source.

Reagents

Normally equipped laboratory (Note 2).

Precautions

Safety: Use extreme care in handling the cooling mixture(s)

and the cold tubes to avoid frost burns.

Procedural: No unusual precautions.

Page 1 of 3

Hit- 1111:1 h<nl described hus U;<;n .ni.iph.-tl lioin i-itin-i tn.i, iiivcsln.i.itiuti:. ni hlci.ilun: ;nin-i.-(lnr,.-; or Imlh The L)»w Cumin,] I'ltiput .iimn du«s inn .

,-uiy liiihilily in connection with Ihi: us*: of this mtMlmii Appltr.ibilily in samples o> mteittSt must bt; Ji^.n-iKiiiiud by !hi'"tii»ri Tbt-, tncltxxl sh

|»- M:pini1m:i;d or published in whole 01 pint willuxit wriltei) pftiiutssion of Iho Dow CnriniU) Cixporjlnin

DOW CORNING CORPORATION. MIDLAND, MICHIGAN 48640 TELEPHONE 517 496-4000
CTM 0133 2

Parameters

If compliance with ASTM D-97 " is specified, the estimated

Pour Point must be known to allow for proper sample handling.

For single temperature cooling, a mixture of dry ice and

acetone will be used unless otherwise specified.

Procedure

Stabilize the liquid to be tested for at least 24 h at room

temperature. Pour the liquid into the glass flask up to the

2-1/8 in. mark. Close the flask with the cork which

supports the thermometer vertically in the center of the

flask with the bulb 1/8 ± 1/32 in. (3 mm) below the surface

of the material. Place the glass flask in the brass jacket

and carefully lower the brass jacket into the Dewar flask

(Note 2) containing a mixture of dry ice and acetone.

Periodically remove the glass flask and tip it, observing

the surface of the liquid. If the material does not flow,

read and record the temperature. Add 5°F to that value and

report the number as the Pour Point (Note 3).

If the temperature of the liquid reaches -40°F (-40°C),

transfer (Note 4) the brass jacket to a new Dewar flask

containing liquid nitrogen and continue the observations

until the material does not flow or the temperature

stabilizes and report the value as Pour Point.

If the material crystallizes at any point, stop the test and

report "Crystallized at °F".

Standardization

The thermometers should be standardized at least once every

three months.

Calculations

None required.

Precision and Accuracy

The repeatability of the value reported (the maximum

expected difference between two independent results) should

not exceed 5°F. the 95% confidence level.

Notes

The values obtained by this method do not relate to

other storage or cooling conditions. For example, a

material may have a Pour Point of -80°F as determined

by this method and be found to be completely unmoving

after storage at -40°F for 24 h. No precautions are

taken to prevent supercooling.
CTM 0133

2. Compliance with ASTM D-97 requires'the use of a series

of baths, each cooler than the preceding one.

Suggested baths are:

A. Water and ice.

B. Water, ice and NaCl or CaCl2.

C. Acetone and dry ice (the amount of dry ice may be

varied to achieve the desired temperature).

D. Liquid nitrogen.

It also requires preheating of the liquid and

controlled cooling. The transfers from bath to bath

are dictated by the temperature of the . liquid

approaching the temperature of the bath.

The same reporting and observation conditions apply.

3. If the observed Pour Point is -38°F, then the reported

value will be -33°F (-38 +5 = -33).

4. For materials expected to have Pour Points below -40°F,

place the jacket directly into the Dewar flask

containing liquid nitrogen.

References

ASTM D-97

IP 15

BS 4452

Figures, Graphs, and Sketches

None. " -—. -

Ed. Form.

11/82

JEW

12 :R
DOW CORNING

corporate test method

FLASH POINT—Pensky Marten Closed Cup

July 1, 1975 CTM 0021A

• Abstract

This procedure should be used on materials similar to fuel oils,

lube oils, suspensions of solids, liquids that tend to form a

surface film under test conditions, and other liquids (Note 1).

The material is placed in a Pensky Marten Closed Cup flash apparatus. Periodically during a controlled temperature rise, a flame

is placed into the confined air space over the sample. The temperature at which the material will flash, but does not continue

to burn, is recorded. This procedure is based on ASTM D93, E134,

and IP34 and the results are reported in degrees fahrenheit.

Apparatus

Tester: Pensky Marten Closed Cup to meet ASTM E134. Fisher

Scientific, Pittsburgh, PA, Cat. No. 13-493.

Thermometer: ASTM Specification as listed, Fisher Scientific

ASTM Range, F Cat. No.

9F 20-230 13-500

10F 200-700 13-505

Reagent s

Normally equipped laboratory.

Precautions

Safety: The possibility of fire and explosion exists. The

nature of the material under test should be known.

Procedural: No unusual precautions.

Parameters

The approximate flash point should be known to allow for proper

heating rate^and selection of thermometer. Flash point is

reported in F unless otherwise specified.

Procedure

The nature of the material being tested dictates which of the

following procedures to use.

Page 1 of 3

The method described has b

any liability in connection w

be reproduced or published

DOW CORNING CORPORATION, MIDLAND, MICHIGAN 48640 TELEPHONE 517 496-4000

The method described has been adapted from either our investigations or literature procedures or both. The Oow Corning Corporation does not assume

any liability in connection with the use of this method. Applicability to samples of interest must be ascertained by the user. This method should not

be reproduced or published in whole or part without written permission of the Oow Corning Corporation
CTM 00.21A

Solutions or clear liquids: Fill the cup to the fill mark with

Sample. Place the lid on the cup. If the material flashes at

or below room temperature, cool to at least 30°F below the

expected flash point. Place the cup in the holder and lock in

position. Put the thermometer (Note 2) in place. Turn on

the stirrer to 105 + 15 rpm with the action in a downward

direction. Light the test flame and adjust to a 5/32 + 1/32

in. diameter'. Begin heating the sample at 10 ± l°P/min. At

about 30°P below the expected flash point, begin applying

the test flame as follows:

1. Plash below 220°P once every 2°F

2. Plash above 220°F once every 5°F

The flame should be lowered in about 0.5 sec., left in the

lowered position for about 1 sec., and quickly raised. Discontinue stirring when applying the flame. Record the lowest

temperature at which the test flame causes a distinct flash in

the interior of the cup (Note 3). Report the temperature to

the nearest degree (Note 4).

Materials containing suspended solids: Follow the above procedure except for the following:

1. Initially adjust the temperature to at least 20°F below

the expected flash point.

2. For flash points below 150°P, fill the air space between

the cup and the interior of the air bath with water at

the initial temperature of the test equipment and sample.

3. The stirring will be at 250 + 10 rpm.

4. The temperature- rise throughout- the test will be not less

than 2 nor more than 3°F/min.

Standardization

The thermometer should be standardized or replaced at least

once every month.

Calculation

None required.

Precision and Accuracy

The precision of this method should be as follows:

Below 200°F Above 200°F

Repeatability + 4 +10

Reproducibility + 6 +_ 15
CTM 0021A

Notes

1. This method should be used for those liquids which have

a viscosity of 45-SUS (6 cSt) or more at 100°F (37.8°C)

or that contain suspended solids, or have a tendency to

form a surface film while under test.

2. Choose the correct thermometer for the temperature range.

3. Do not confuse the true flash with the bluish halo that

sometimes surrounds the test flame.

4. Observe and record barometric pressure at the time of

test. When pressure differs from 760 mm.Hg, correct the

flash point by means of the following equation:

Corrected flash point = °F + 0.06(760 - P)

Corrected flash point = °C + 0.03(760 - P)

F .= Observed flash point °F

C = Observed flash point °C

P = Barometric pressure, mm Hg

Record flash point to nearest °F or 0.5°C.

Reference

ASTM D93, E134

Institute of Petroleum 34

Figures, Graphs, and Sketches

None

Denotes change
DOW CORNING

corporate test method

FIRE POINT - Liquids - Cleveland Open Cup

September 29, 1970 CTM 0052

Abstract

The temperature at which a liquid will sustain a fire for at

least five seconds in a Cleveland open cup test apparatus is

determined and reported as the Fire Point. After the Flash

Point of the material is reached, the heating is continued

at the same rate until the application of the flame results

in a sustained fire. The procedure is based on ASTM D-92

and the results are reported in degrees Fahrenheit.

Apparatus

Burner: Meeker, Central Scientific Co., Chicago, IL, Cat.

No. 11043.

Cup: Cleveland Open Cup Flash Tester with heating plate.

Fisher Scientific Co., Pittsburgh, PA, Cat. No. 13-529 (Note

1 > -

Thermometer: ASTM open flash, graduated in 5°F intervals

from 20 to 760°F. Fisher Scientific Co., Cat. No. 13-535

(ASTM 11F). The thermometers must be a low immersion style.

Reagents

Normally equipped laboratory.

Precautions

Safety: The possibility of a continuing fire or explosion

exists. The nature of the material under test should be

known. Adequate precautions must be made for the protection

of the operator and for the removal of toxic vapors and

products of combustion. A fire extinguisher should be

available.

Procedural: No unusual precautions.

Page 1 of 3 .

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DOW CORNING CORPORATION, MIDLAND, MICHIGAN 48640 TELEPHONE 517 496-4000
CTM 0052 2

Parameters

The approximate flash point should be known to allow for

proper flame regulation. Other types of flash point apparatus may be specified. The results may be reported as

degrees Centigrade.

Procedure

Fill the cup with material so that the surface level is at

the filling line at room temperature. Place the thermometer

vertically in the sample so that the bottom of the bulb is

1/4 ± 1/16 in. (6.4 mm) above the bottom of the cup. Turn

on the Meeker burner and adjust the flame so the rate of

heating does not exceed 30°F/min. At 50°F below the

expected flash point, reduce the rate of heating to 10 ±

l°F/min.

Adjust the test flame to a 5/32 ± 1/32 in. (4.0 mm)

diameter.

If the flash point is also being determined, start flame

application at least 50°F below the expected flash point

(Note 2). Pass the flame over the material at 5°F intervals.

Continue the application past the initial flash point until

the material continues to burn for at least 5 sec. Record

and report this temperature as the Fire Point (Note 3).

Standardization

The thermometer should be standardized or replaced once

every month.

Calculations

None.

Precision and Accuracy

The repeatability of the value reported (the maximum difference between two independent results) should not exceed 15°F

at the 95% confidence level.

Notes

1. Other types of flash point testers may be specified.

In the case of a dispute, when an automatic flash point

tester is used for determination of Fire Point, the

manual method shall be considered the referee method.
CTM 0052 2

2. The test flame must pass horizontally across the center

of the cup with a smooth continuous motion not more

than 5/64 in. (2 mm) above the upper edge of the cup.

The pass should be first in one direction and then in

the opposite direction. The time consumed in a pass

should be about 1 sec.

3. Variations in barometric pressure affect the Fire

Point. A correction should be applied, as required:

PRESSURE ADD CORRECTION

mm of Hg Degrees Fahrenheit

715-635 5

635-550 10

References

ASTM D-92.

Institute of Petroleum 36.

DIN 51 376.

Figures, Graphs, and Sketches

None.

Ed. Form.

9/79

JEW

4:B
DOW CORNING

corporate test method

VOLUME RESISTIVITY—Liquid and Semi-Solid Insulating Materials

July 20, 1972 CTM 0272

Abstract

The volume resistivity of liquid insulating materials is measured

in a Balzbaugh cell and that of semi-solids in a special cell.

The measurement is made with a commercial ohmmeter and the

method is based on ASTM D 1169.

Volume resistivity is defined as the ratio of the potential

gradient parallel to the current in the material to the current

density. In the metric system the volume resistivity of an

electrical insulating material in ohm-cm is numerically equal

to the volume resistance in ohms between opposite faces of a

1 cm cube of material.

Apparatus

Capacitance bridge: Type 7l6C (Schering type), General Radio

Co., West Concord, Mass.

Cell: Balzbaugh, two-terminal, 100 MMf, Balzbaugh Laboratories,

Inc., South Hingham, Mass. Use for materials 1000 cS or less

unless otherwise specified.

Reference standards: Comparison resistors, type CR, nominally

10 , 10 , and 107 megohms. Rhode and Schwarz Sales Co., Passaic ,

N.J. Calibrated, certified} and traceable to the National Bureau

of Standards.

Semi-solid sample holder: See Figure 1.

Tera-Ohmmeter: Type h 4/10, Rhode and Schwarz Sales Co.

Reagents

Normally equipped laboratory.

Precautions

Safety: Normal t;a.fe laboratory practices.

Procedural: No unusual precautions.

Page 1 of 5

The method described his been adapted from either our investigations or literature procedures or both. The Dow Corning Corporetion does not assume

any liability in connection with the use of this method. Applicability to samples of interest mual be ascertained by the user. This method should not

b« reproduced or published in whole or pact without written permission of the Dow Corning Corporation

DOW CORNING CORPORATION. MIDLAND, MICHIGAN 48640 TELEPHONE 517 496-4000
CTM 0272

Parameters

Other potentials and electrification periods may be specified.

Other temperatures and sample conditioning may be specified,

Procedure

Condition the material at 23 ± 2 C and make all determinations

under the same conditions, unless otherwise specified. Add a

sufficient amount of material to be tested to the correct clean

dry test cell (Note 1) to cover the capacitor plates (Note 2).

Attach the leads from the ohmmeter to the test cell with the

positive lead to the inner electrode and the negative lead to

the outer electrode. Adjust the applied voltage to 500 volts

and measure the resistance (R) (Note 3) after 60 sec of electrification. Calculate the volume resistivity (VR) and report the

value.

Standardization

The equipment should be calibrated and adjusted every three months

to produce the certified values of the reference standards.

The Balzbaugh cell should be calibrated at least once every six

months as follows: Fill the cell with reagent grade cyclohexane

(other pure materials of known dielectric constand may be used—

cyclohexane is used because of its extremely low electrical.loss)

and connect the leads to the capacitance bridge. Set the bridge

capacitance dial at 100 yuf and balance the bridge using the

external capacitor. Disconnect the leads from the cell and rebalance the bridge using the bridge capacitor. Read and record

the bridge capacitor (Cc). Remove the cyclohexane and dry the

cell. Repeat the above with the empty cell and record the bridge

capacitor reading aa the air capacitance (Ca). Calculate the

cell factor (Gf).

The semi-solid sample holder (Fig 1) should be calibrated at least

once every six months as follows:

Assemble the cell completely. Connect the cell to the

bridge and screw the micrometer adjustment down until the top

electrode Just touches the base. Record the micrometer dial

reading. Move the top electrode up to produce a spacing of 0.025

in. and lock the spindle. Fill the cup in the base with reagent

grade cyclohexane using an eye dropper and proceed as outlined

above for the Balzbaugh cell.
CTM 0272

c« =

Cc - C

p = _£ §a_

v Krt - K c a

C = capacitance of cyclohexane

C = capacitance of air

K = DK of cyclohexane (2.0150)

K = DK of air (1.0006)

3.

Calculations

VR = (Cf)(R) = ohm-cm

Cf = cell factor

R = resistance measured in ohms

Precision and Accuracy

The precision of the reported results should be in the range of

± 5 %.

Notes

1. The semi-solid sample holder (Fig 1) is used for materials

which have a viscosity greater than 1000 cS, unless otherwise specified. The upper electrode is adjusted to give

a spacing of 0.025 in. and the spindle is locked. The cup

in the base is filled with material to be tested a,nd the

cell carefully assembled until tne Teflon® sleeve is fully

seated on the base and the upper electrode forced into the

material to be tested.

Both cells must be cleaned using.a dry low-boiling hydrocarbon,

After a final rinse, the cell should be heated at 110 C for

about 10 min or placed in a vacuum chamber to remove the last

traces of solvent and prevent moisture condensation.

2. When both dielectric constant and volume resistivity measurements are required on the same material, fill the cell and

make the dielectric constant measurement first.

3. The measured value (R) is frequently reported directly as

Insulation Resistance. The number is of limited value

since it is dependent upon the cell configuration and the

electrode spacing.
CTM 0272

References

ASTM D 1169

Figures, Graphs3 and. Sketches

1 Figure

MCL x

CTL x
Figure 1

CTM 0272

Micrometer spindle

0 to 1 in.

Jacks to

bridge

2-1/;

2 in. ID, 2-1/2 in. OD Teflon® tube with an opening about

1-1/2 in. wide and 3/4 in. high on the bottom edge to allow

observation of the electrode and sample.

Brass electrode with base bevelled about 1 to 2° to prevent

air entrapment

Stainless steel

Jit I IT c'

Into ba:.

: to complete electrical circuit. Slip fit

Liquid and Semi-Solid Cell

APPENDIX III

This appendix contains complete reports of shear viscosity,

thermal conductivity, and emittance/transmittance measurements on

Task II fluids.

Shear Viscosity Savant, Inc., Midland, MI

Thermal Conductivity Dow Thermal Laboratory

Midland, MI

Emittance/Transmittance Analytical Research,

Dow Corning
SAVANT, INC.

234 E. LARKIN STREET

MIDLAND. MICHIGAN 4864O-O111 1985 September 16

Dr. Robert Buch

Dow Corning U.S.A.

Mail #108 :

Midland, MI 48640-0994

Dear Dr. Buch:

We have, as you know from our phone conversation of August

28th, completed the high and low temperature, high and low shear

stress analyses of the two samples you sent us, using the Newtonian

calibration fluid S-3 from Cannon Instrument Company for reference

at low temperatures. In the written report on the subject, you

requested that we note the shear stresses obtained.

The attached report presents the desired information. If

you need further input, please let me know. It has been good

working with you on this interesting assignment and I hope we

may serve you and your associates again.

Yours very truly,

Theodore W. Seby, Director

Research & Development

TWS/cp

Attachment

cc: Mr. Thomas J. Tolton, Manager, Savant Laboratories

Phone (51 7) 631-SO5O

Telex 509860 SAVANT INC. HI
Report DCC-2-1

to

Don Corning Corporation

High/Lou, Temperature/Shear Analysis of Coolants

by

Savant Laboratories

Midland , Michigan

1985 September 11

INTRODUCTION

A meeting between Dr. Robert Buch of DON Corning Corporation

and Messrs. Thomas Tolton and Theodore Selby of Savant, Inc. on

July 17th, 1985, was held at the Savant offices to define Dow

Corning Corporation's needs for viscometric analysis of two

fluids being prepared as special coolants. The critical

questions raised were whether or not the fluids were Newtonian or

not and whether the Savant Laboratories could perform the

necessary measurements. The answer to the latter question was

affirmative with the understanding that Savant would have to

develop the necessary procedure in the process. It was explained

that much of Savant work is in the area of advanced materials

studies where orignal techniques and equipment must be developed.

In the ensuing technical discussion it was noted by the

Savant representatives that the degree-of non-Newtonian behavior,

while usually associated with the difference in viscosity

determined at widely different shear rates, really is dependent

on shear stress — the force per laminar area of shear. Thus,

the critical element at both low and high temperatures in

determining non-Newtonian behavior was in applyin g a wide range

of shear stress to the fluids.

SUMMARY

Applyin g widel y differin g

factor of up to 4,000), neither

markedly non-Newtonian.

shear stresses (varying by a

coolant gave evidence of being

The precision of the viscometric analyses allows the

statement that Coolant EC 721-38-7 is probably slightly nonNewtonian at low temperatures."

Coolant EC 721-38-17 seems completely Newtonian
.page 2

FLUIDS

Two fluids were submitted with the code identifications EC

721-38-7 and EC 721-38-17. Two more fluids of known Newtonian

viscometric properties were also included for reference and

procedural development purposes. These latter fluids were S-3

froffl Cannon Instrument Company and DC 705 iron the Dow Corning

Company. The former, S-3, was used to calibrate the two lowtemperature viscometers and the latter was used to develop all

the test procedures since the experimental fluids were available

in relativel y limite d volumes.

EQUIPMENT

Four viscometric instruments were used two of which were

either totally or partially developed at Savant Laboratories. Of

the six techniques used to generate the data,- four were totally

developed at the Savant Laboratories and, of the remaining two,

both were modifications of other procedures used by the ASTM.

Tapered Bearing Simulator Viscometer (TBS) -

A world-class, very high shear rate instrument invented at

Savant, developed by the Savant Laboratories and manufactured and

marketed by Tannas Co. of Midland , Michigan, the instrument is

capable of

1. shear rates from 100,000 to values in excess of 3,000,000

I/sec,

2. shear stresses from less than 1000 to more than -1,000,000

dynes/sq.cm,

3. viscosities from less that 1 to more than 100 centipoise

at full shear, and

4. temperatures from room temperature to over 200 C.

Over 70 units are presently used world-wide.

Scanning Brook-field Viscooeter Technique (SBT) -

A world-class instrument and .low-temperature, low-shear

technique utilizing the Siverso Programmable Cold-bath and the

Brookfield LVTD Recording Rotational Viscometer. The technique,

developed by the Savant Laboratories is under round-robin

evaluation by the ASTM and is a required analysis for multi-grade

engine oils used in Ford vehicles around the world.

Shear rates range from 12.4 to -2480 I/sec wit h shear

stresses up to 5000 dynes/sq.cm.

Cold-Cranking Simulator (CCS) -

A world-class instrument and technique developed by the

Cannon Instrument Company. The technique.has been modifie d by

the ASTM and a special version developed and applie d by the

Savant Laboratories. The.temperature range covered by by the CCS

is above 0 C to below -40 C. Shear rate and stress must be

calculated from dimensions and rotor speed; essentially, the

shear rate is variable between 15,000 and 300,000 I/sec whil e the

shear stress is constant at about 1,000,000 dynes/sq.cm.
. . . page 3

Ubbelohde Suspended Level Capillary Viscoaeter (USLCV) -

A world-class instrument used for very accurate lower shear

capillary viscometry, particularly at a variety of temperatures

where the constant calibration constant of the instrument makes

it superior to the more common Ostwald capillary viscometer

(which is subject to calibration change with temperature because

of the effect of temperature on the density of the fluid). The

nominal capillary diameter of the USLCV instrument used was 0.63

am, the bulb volume was 3.0 cubic en, and the flow rates ranged

from 286 to 382 seconds to empty the bulb. The average shear

rate can be calculated from these values and the Kroepelin

equation: The average shear rates ranged from about 260 to 360

I/sec, and the shear stresses from about 10 to 25 dynes/sq.cm.

Density -

Work in the low-shear USLCV produced results in units of

Kinematic Viscosity since the hydrostatic head is the force

drivin g the fluid and the viscometric result is a consequence of

both physical properties. These Kinematic values had to be

converted to units of Absolute or Dynamic Viscosity in order to

be compared to the high shear results (which, for obvious reasons

associated with the absence of dependence on gravity to produce

flow, are nearly always produced in units of Dynamic Viscosity).

Since the Dynamic Viscosity can be found from the product of

density multiplie d by the Kinematic Viscosity, it was necessary

to determine the density of the fluids at the temperature of

viscometric test in the capillary. Savant Laboratories developed

a method for determining density in the same high-temperature

bath as used for capillary viscometry. This technique is known

simply as the Savant Density Technque and it was used in the

present evaluation.

RESULTS AND DISCUSSION

The raw results of the study are shown in Table 1. The wide

viscosity differences in the two coolants made it necessary to

develop special approaches includin g the use of reference fluid s

to specially calibrate the low temperature viscometers,

particularly for the lowest viscosity coolant. In this case the

Cannon Reference Fluid S-3 was applied to directly calibrate the

CCS and the Brookfield viscometers at -40 C.

The Scanning Brookfield approach was not without problems

since the low spindle speed used in this technique, 0.3 RPM, gave

poor sensitivity at lowest viscosities. As a consequence, a

further modification in the technique was made by running the

viscometer at the highest speed which would keep the pen on the

chart. The results of this technique are noted simply as

Brookfield Technique.

The analyzed results taken from the raw data are given in

Table 2. Here a quick perusal will show that neither of the

fluids show marked departure from Newtonian behavior. This is

evident in the similarities in viscosities taken at widely
page 4

different shear stresses. At the most, Coolant EC 721-38-7 shows

a 107. decrease in viscosity at very high shear stresses in the

CCS viscometer at low temperatures. This is almost within

experimental error which latter is about 2X repeatability at the

952 confidence level with the Brookfield and about 37.

repeatability at the 95X confidence level with the CCS for a

combined error of 67. repeatability.

In special regard to the results with Coolant EC 721-38-7:

of the two fluids examined, this latter coolant would be the one

most expected to give non-Newtonian results principly because of

its molecular configuration. Shear stresses of 1,000,000

dynes/sq.cn. show a marginally significant effect of shear stress

on viscosity while shear stresses of less than 100,000

dynes/sq.cm. show none. A part of the difference in the results

may also be attributed to the closer packing of the molecules at

the lower temperature — a condition which often leads to more

shear dependence.

Withi n the different techniques tried at low temperature,

the simple calibrated Brookfield gave the most dependable results

and, as wil l be noted, these are the results used in the analyses

presented in Table 2.

CONCLUSIONS

The study has shown that, to any meaningful degree, neither

coolant study shows non-Newtonian behavior. Whether this fact is

the most desirable situation or not has not been questioned.

Conceivably, a strongly non-Newtonian coolant could give very

desirable characteristics in reducing pumping losses.

The study has also shown how state-of-the-art equipment and

techniques give very acceptable results at both low and high

temperatures and shear stresses/rates. Use of shear stress

rather than shear rate as a measure of viscometric response is

the best approach toward the distinction of non-Newtonian

behavior. .

Signed __

Date
PROJECT: DCC-O2

DATE: 1985 August 30

High-Temperature Tests:

Sample KV15O

S850802P 4.74 cSt.

S850SO2Q 6.43 cSt.

(TABLE 1)

Data Summary

Den so) 150

0.8480 g./ml

0.9864 g./ml

CalcSlSO TBS150

4.02 cP. 4.13 cP.

6.34 cP. 6.49 cP.

Low-Temperature Tests:

Sample 'mp. , C.

-5

-10

-15

CCS

I

t CT ^D

OD C.r m

1610 cP.

2940 cP.

62OO cP.

SET,

1956

3358

6890

f 7-^TCl

#1

cP.

cP.

cP.

r-P

SET,

1298

2775

6429

1 AQ^r-i

#2

cP.

cP.

cP.

r-P

Brk-fld Vi

1 oo Cn .

1705 cP.

3226 cP.

6818 cP.

1 TA^n f-p

NOTE: Savant ID

S85O802P

S850802Q

SIGNED:

Dow Corning ID

EC 721-38-17

EC 721-38-7
TABLE 2

Comparison of Viscosities of Experimental Coolants

at Different Temperatures and Shear Conditions

Coolant Savant IDi

EC 721-38-

17 s 850802 p

17

17

17

7

7

7

7

7

7

7

7

s 850802 q

Device/

Technique

Brook-f i el d

CCS

USLCV

TBS

Brook* ield

CCS

Brookf ield

CCS

Brookf ield

CCS

USLCV

TBS

Temp.

C

-40

-40

150

150

-5

-5

-10

-10

-15

-15

150

150

Shear

Stress,

Dyne/sq.cn.

1,000

1,000,000

10

40,000

2,370

1,000,000

4,840

1,000,000

4,540

1,000,000

25

65,000

Vi

LON Te

158

165

1700

1610

3230

2940

6820

6200

Viscosity, cP

High Te«p.

Ratio

4.02"

4. 13"-

6.34^

6.49-

0.96

0.97

1.06

1.10

1.10

0.98
DOW CHEMICAL U.S.A.

MIDLAND. MICHIGAN 48674

MICHIGAN DIVISION

August 26, 1985

Robert R. Buch

Dow Corning Corporation

408 Building

Midland, MI 48686

Dear Bob:

The new hot-wire transient technique for the absolute determination

of thermal conductivity of liquids was used to investigate the two

silicone oil samples (Ref: E6721-38-8 and E6721-38-18). The theory

of the transient technique is well discussed elsewhere;

J. J. DeGroot, J. Kestin and H. Sookiazian, "Instrument to Measure

the Thermal Conductivity of Gases," Physica 75, 454-482, 1974.

Numerous values at each of the twelve temperatures (27-159°C) were

determined for each sample. Average values for each temperature of

the two samples are given in the attached Tables I and IV, along with

the temperature dependent quadratic equations (Tables II and V)

obtained by a curve fitting of the observed data. The percent

deviation of the experimental data from the derived quadratic

equation is <0.5 for both samples. Caution: DO NOT use these

equations to obtain data below 10°C or above 170°C.

The temperature dependence thermal conductivity is nonlinear for Ref:

£6721-38-^81" see attached Figure 1.

«Sincerely • i ,

c.

George C. Karris

Analytical Labs

Thermal Group

1707 Building

jw

Attachments

cc: T. W. McGee, 1707 Building

W. R. Kracht, 1707 Building

iiQiialitY==

l*ci lui uiance

AN OPERATING UNIT OF THE DOW CHEMICAL COMPANY Means More At Ocw
AUG 08f 1985 15MO:06 PHYSICOCHEMICAL STUDIES DATASET 1 PAGE

NO.

'THERM. COND. OF SILICONS OIL E6721-38-8f G.C.KARRIS 8-10-85'

CURVE FITTING BY ORTHOGONAL POLYNOMIAL OF POWERS 0

SCALE X ACT. X Y (DBS.) OBS-CALC

BY 1 TO

7. DEV

1

2

3

4

5

6

7

8

9

10

11

12

-0.952381

-0.862311

-0.775194

-0.639350

-0.503507

-0.361757

-0.221484

-0.079734

0.066445

0.361757

0.652639

0.952381

29.9000

36.0000

41.9000

51.1000

60.3000

69.9000

79.4000

89.0000

98.9000

118.9000

138.6000

158.9000

0,13800

0.13810

0.13750

0,13630

0.13570

0*13510

0.13450

0.13320

0.13210

0.12950

0.12700

0.12400

-0.00017

0.00033

0.00014

-0.00037

-0,00022

0.00003

0.00034

0.00003

0.00002

-0.00017

-0.00000

0.00004

-0.123

0.238

0.101

-0.272

-0.160

0.026

0.256

0.022

0.013

-0.130

-0.003

0.031

.J
,- TL

AUG 08f 1985 15MO:06 ---- PHYSICOCHEMICAL STUDIES ---- DATASET 1 PAGE

'THERM. COND. OF SILICONS OIL E6721-38-8/ G.C. KARRIS 8-10-85'

CURVE FITTING BY ORTHOGONAL POLYNOMIAL OF POWERS 0 BY 1 TO

U = 4

TL = 0*0

CP TOLERANCE =

SL = .0.0

WEIGHT =1 PS = 0 PD = 1

DT = 10.00

1.00%

HL = 0.0

PF = 2

SCALE FACTOR

67.7250000000

LINEAR TRANSLATION

94.4000000000

TH

TREF =

A

-1.000

180.00000

0.0

B FRA

1.000 1.0

REDUC FAC

1.00000

DIAGNOSTIC STATISTICS TABLE

PWR DF PCT RMS '/. DEV SUM DEVSQ/DF RATIO SUM UT*DEVSQ

0 11 .122D-02 3.493 .204D-04 0.0000 .224D-03

1 10 .229D-04 0.478 .399D-06 0.0196

2 9 .295D-05 0.172 .5450-07 0.1367

.3990-05

,4900-06

RATIO

0.0002

0.0178

0.1230

2TH POWER (FINAL) POLYNOMIAL COEFFICIENTS FOR Y = FCSCALED T)

.132586499752 -7.459226615760-03 -1 .676836937610-03

NON-SCALED POLYNOMIAL COEFFICIENTS FOR Y = F(T) o *

.139725813951 -4,111678880490-05 -3.655887345660-07 j lO-JVO C

\o'C
AUG 08r 1985 15.'40:06 PHYSICOCHEMICAL STUDIES DATASET 1 PAGE

'THERM. COND. OF SILICONS OIL E6721-38-8f G.C.KARRIS 8-10-85'

CURVE FITTING BY ORTHOGONAL POLYNOMIAL OF POWERS 0 BY 1 TO 2

SCALE X ACT. X

-1

1.393872

1.246216

098560

0.950904

0.803248

-0.655592

-0.507937

-0.360281

-0.212625

-0.064969

0.082687

0.230343

0.377999

0.525655

0.673311

0.820967

0.968623

1.116279

1.263935

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

90.000

100.00

110.00

120.00

130.00

140.00

150.00

160.00

170.00

100,00

.13928

.13876

.13816

.13750

.13676

.13594

.13506

.13410

.13306

.13196

.13078

.12953

.12820

.12680

.12533

.12379

.12217

,12008

DY/DX

-4.1117D-05

-4.8429D-05

-5.5740D-05

-6.30520-05

-7.0364D-05

-7.7676D-05

-8.4987D-05

-9.2299D-05

-9.9611D-05

-1.0692D-04

-1.1423D-04

-1.2155D-04

-1.2886D-04

-1.3617D-04

-1.4348D-04

-1.5079D-04

-1.5811D-04

-1.6542D-04

-1.7273D-04

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07

.-7.3118D-07

-7.3118D-07

-7.3118D-07

-7.3118D-07
AUG 14» 1985 8:07M2 PHYSICOCHEMICAL STUDIES DATASET 1 PAGE

NO.

J

'THER. CONB. OF SILICONE OIL £6721-38-18, G.C.KARRIS 8-14-85'

CURVE FITTING BY ORTHOGONAL POLYNOMIAL OF POWERS 0 BY 1

SCALE X ACT. X Y (OB.S.) OBS-CALC

TO

•/. BEV

1

2

3

4

5

6

7

8

9

10

11

12

-0.952381

-0.840847

-0.746696

-0.611986

-0.475828

-0.339670

-0.202064

-0.060112

0.083288

0.371537

0.658338

0.952381

27.2000

34.9000

41.4000

50.7000

60.1000

69.5000

79.0000

88.8000

98.7000

118.6000

138.4000

158.7000

0.15220

0.15130

0.15030

0.14820

0.14640

0.14480

0.14320

0.14120

0.13950

0.13540

0.13120

0.12720

-0.00025

0.00019

0.00033

-0.00011

-0.00021

-0.00008

0.00010

-0.00004

0.00017

-0.00000

-0.00017

0.00009

-0.165

0.123

0.219

-0.076

-0.143

-0.055

0.067

-0.030

0.120

-0.001

-0.130

0.069

J
AUG 14» 1985 8.07.42 ---- PHYSICOCHEMICAL STUDIES ---- DATASET 1 PAGE

'THER. COND. OF SILICONE OIL E6721-38-18* G.C. KARRIS 8-14-85'

CURVE FITTING BY ORTHOGONAL POLYNOMIAL OF POWERS 0 BY 1 TO 2

U = 4

TL = 0.0

CP TOLERANCE =

SL= 0.0

WEIGHT = 1 PS = 0 PD = 1

DT = 10.00

1.00%

HL= 0,0

PF = 2

SCALE FACTOR

69.0375000000

LINEAR TRANSLATION

92*9500000000

TH =

TREF =

A

-1.000

180.00000

0.0

B FRAi

1.000 1.0

REDUC FAC

1.00000

DIAGNOSTIC STATISTICS TABLE

PWR DF PCT RMS % DEV SUM OEVSQ/DF RATIO SUM UT*DEVSQ RATIO

0 11 .3440-02 5*867 .644D-04 0.0001 .709D-03 0.0007

1 10 .495D-05 0.223 .100D-06 0.0016 .100D-05 0.0014

2 9 .1790-05 0.134 .3830-07 0.3824 .3450-06 0.3441

2TH POWER (FINAL) POLYNOMIAL COEFFICIENTS FOR Y = F(SCALED T)

.140445613340 -1.330296491110-02 -7.323867639980-04

NON-SCALED POLYNOMIAL COEFFICIENTS FOR Y = F(T>

.157028715397 -1.641258482990-04 -1 .536633774270-07 j \ 0 - 1 70 °C

> Vv, 7
VI

AUG 14f 1985 8:07M2 PHYSICOCHEMICAL STUDIES DATASET 1 PAGE

'THER. COND. OF SILICONS OIL E6721-38-18* G.C.KARRIS

CURVE FITTING BY ORTHOGONAL POLYNOMIAL OF POWERS

SCALE X

-1.346370

-1.201521

-1.056672

-0.911823

-0.766974

-0.622126

-0.477277

-0.332428

-0.187579

-0.042730

0.102118

0.246967

0.391816

0.536665

6.681514

0.826362

0.971211

1.116060

1.260909

ACT. X

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

90.000

100.00

110.00

120.00

130,00

140.00

150.00

160.00

170.00

100.00

.15537

.15368

.15197

.15022

.14844

.14663

.14479

.14292

.14101

'.13908

.13712

.13512

.13310

.13104

.12895

.12683

.12469

«12251

DY/DX

-1.6413D-04

-1.6720D-04

-1.7027D-04

-1.7335D-04

-1.7642D-04

-1.7949D-04

-1.8257D-04

-1.8564D-04

-1.8871D-04

-1.9179D-04

-1.9486D-04

-1.9793D-04

-2.0101D-04

-2.0408D-04

-2.0715D-04

-2.1022D-04

-2.1330D-04

-2.1637D-04

-2.1944D-04

8-14-85'

0 BY 1 TO

D2Y/DX2

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07

-3.0733D-07
— - - - •• '-\ - ••_•'•• ' '.'''' ~

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EXTERNAL

AUTHOR:

DEPARTMENT:

DATE:

TITLE:

A. L. SMITH

ANALYTICAL RESEARCH

19850828

INFRARED EMISSION SPECTRA OF TWO SELECTED SILICONE FLUIDS

ABSTRACT

We were requested to measure the emissivity and transmittance of

two candidate fluids over the wavelength range 3 to 55 micrometers. The emissivity was'measured at 150C from 3 to 25 micrometers using the Nicolet FTIR spectrometer together with an

external oven and first surface mirrors to direct the radiation

into the spectrometer. Because of detector limitations, it was

not possible to include the segment 25 to 55 mu; however, this

includes only a relatively small portion of the total energy.

Both fluids act as quite good black bodies in thicknesses of ca.

0.5 mm.

Transmission was measured at two fluid thicknesses over the entire wavelength range.

INFORMATION RETRIEVAL INDEX

Infrared emission, Infrared emissivity, Fluid droplet

emissivity, Liquid droplet radiator.
EXTERNAL

page 3

INTRODUCTION

As a part of contract NAS3-24400 between Dow Corning and

NASA- Lewis Research Center entitled "Evaluation of

Working Fluids for the Liquid Droplet Radiator" we were

asked to raeasure:(1) the emissivity and (2) the fraction

of energy transmitted as a function of wavelength through

a nonopaque layer of fluid in the range 3-55 micrometers.

The Nicolet 60SX FTIR spectrometer was utilized to make

these measurements, although detector limitations

precluded emission measurements in the 25-55 mu range.

Emissivity is defined as the emittance of a thick

(optically opaque) layer. Emittance is defined in two

ways: radiant flux per unit area; or as the ratio of

radiant flux to the flux of a blackbody at the same

temperature and viewing geometry. The latter definition

was used in the work described here.

Transmission measurements were obtained in the usual

manner, using liquid cells of appropriate thickness and

also liquid films on thin polyethylene sheet.

RESULTS AND DISCUSSION

The two fluids tested are identified below.

Analytical Reference Fluid Type Fluid

Sample No. No. No.

71583 E6721-38-5 DC 710 Fluid cut (PhMeSiO) 5

71584 E6721-38-15 DC 200 Fluid cut (Me2SiO) 15

An initial run was made using the TGS (room temperature)

detector in order to insure that the equipment was

properly aligned and functioning. The emission spectrum

of a thin film (ca. 0.01 mm) of fluid No. 5 was obtained

and is shown in Fig. 1. The spectrum is quite

recognizable and confirms that the system was working

properly.
EXTERNAL

page 4

A trial run with the cooled detector (MCT) gave results

which indicated that best results would be obtained with

longer spectrum accumulation time—at least 5 min.

Parameters were set to give the best results (Table 1).

Spectra were then obtained for the two fluid samples at a

thickness of ca. 0.5 mm, and for two "blackbody" samples.

One blackbody sample consisted of soot from a fuel-rich

methane flame, deposited in an Al sample cup. This

blackbody was visually nearly perfect, in that it absorbed

nearly all the incident light. The second sample

consisted of a thick (1 mm) layer of powdered graphite in

an Al cup. Although it was not as absorbing of visible

light as the soot specimen, it was a better blackbody

emitter in the infrared (Fig. 2), probably because the

methane soot sample was not thick enough. The graphite

blackbody spectrum was therefore used for reference.

A calculated Planck function for 423 K is shown in Fig. 3,

and may be compared with the observed blackbody curve.

Dividing the blackbody curve by the Planck function curve

gives the instrument function (Fig. 4).

Single beam spectra were obtained and ratioed as explained

in the EXPERIMENTAL section. Results of the emission

experiment are shown in Figs. 5 and 6. The ordinate

indicates the percent of blackbody emission given off by

the sample. It-is observed that both fluids are excellent

blackbodies, except in the 2000-3000cm-1 region. It is

well known, of course, that strong absorbers are also

strong emitters, so it is no surprise that the silicone

fluids, which absorb strongly in the infrared, are also

good blackbodies.

Results of .the transmission measurements are shown in

Figs. 7-10. Because it is difficult to obtain a cell

thickness of.0.02 mm with any accuracy, spectra were run

as 20% (w/v) solutions in 0.1 mm cells.. Spectra taken at

0.2 mm (Fig. 8) show very strong absorption. The far

infrared (500-100 cm-1) spectra were more difficult to

obtain because of the intrinsically low energy in this

region, and the lack of suitable cell materials. The

approximate thicknesses of these samples were 0.1 and 0.01
EXTERNAL

page 5

mm. Results are shown in Figs. 9 and 10. Operating

parameters are listed in Table 1.

EXPERIMENTAL

The Fourier transform infrared spectrometer was a Nicolet

60 SX, adapted for emission measurements by removing the

external source cover and temporarily placing a 45 degree

first-surface mirror, mounted on a heavy base, in the

instrument in such a position as to direct external

radiation into the interferometer. A temporary aluminum

shield was placed in front of the source to prevent any

radiation from leaking around the 2 7/8 x 3 3/4 in.

diagonal mirror. For the initial range-finding

experiments, the TGS detector was used, but for the final

work, the cooled MCT detector, which is a factor of 5 more

sensitive, was used.

The use of a cooled detector introduces some special

problems, since the detector picks up radiation from the

beam splitter and other room-temperature components of the

spectrometer. To correct for these effects, it is

necessary to make four measurements: sample at 150 C and

at room temperature (21 C); and blackbody at 150 C and 21

C (1). The interferograms for the measurements at the two

temperatures are subtracted, transformed to give single

beam spectra, and then ratioed to give a percent of

blackbody emission.

The oven was adapted from the oven used for

chemiluminescence measurements, and has been described

(2). The photomultiplier was removed from the top, and

replaced with a clamp arrangement which carried another 2

7/8 x 3 3/4 in. mirror to direct the sample radiation into

the spectrometer (Fig. 11). Samples were placed into 2

in. aluminum foil cups, which in turn fit into the sample

carrier in the interior of the oven. The temperature was

regulated using a thermocouple imbedded in the metal wall

of the sample carrier, and the heating elements were also

imbedded in the box surrounding the sample. The

temperature of the air in the sample compartment was

monitered with another thermocouple to 1 degree C, and was
EXTERNAL

page 6

taken as the sample temperature after time for

equilibration.

Data manipulation is easily accomplished with existing

software. To subract interferograms, the specific

commands are: CLS, CLB, BKS (SAM - BKG), to SAM. FPS

gives the single beam spectrum. Ratio using RAS with

sample in SAM and blackbody in BKG. Mathematically,

, _ E(sample) corr.

* ~ E(blackbody) corr.

where E corr. = transform{IG(T2) - IG(T1)}

Interferograms and intermediate spectra are filed in

destination files until needed and moved into the proper

file using the OFM and MOX commands. To generate the

Planck function, set TBB = 423 K and EMY = RN. Then use

BBG to generate the Planck curve.

Table 1

Parameters used were:

Run No.

1 Emiss.

2 "

3 "

Trans .

Trans .

PFN

5

6

6

1

2

DET CAN

TGS 1

MCT 8

MCT 8

TGS 1

TGS-FIR 8

NSS=NSB

128

256

2000

32

256

NDP

2048

2048

2048

8182

2048

NTP

4096

4096

4096

16384

4096

DOCUMENTATION

Documentation for this report is found in book 6369, pp.

86 through 95.

REFERENCES

1. D. Kember, D. H. Chenery, N. Sheppard and J. Fell,

Spectrochim. Acta 35A, 455, (1979).

2. A. Lee Smith, Dow Corning Research Report 1-0030-5728

(Dec. 31, 1984).
ORIGINAL PAGE IS

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APPENDIX IV

ACUTE TOXICOLOGICAL REPORT ON DOW CORNING® 710 FLUID
DOW CORNINGAPPENDIX IV

DOW CORNING CORPORATION

Health & Environmental Sciences

Toxicology Department

ACUTE TOXICOLOGICAL REPORT ON DOW CORNING* 710 FLUID

A sample of DOW CORNING* 710 Fluid was submitted to the Toxicology Department

for the determination of oral toxicity, primary eye and skin irritation

potential and an assessment of industrial handling hazards associated with

acute exposure.

DOW CORNING* 710 Fluid is practically non-toxic when ingested on an acute

basis by laboratory rats (ALD5Q >15.0 g/kg body weight), it is unlikely that

serious injury would result from ingestion of amounts normally encountered

incidental to its industrial use.

Direct eye contact with this material may result in very slight transient

conjunctival redness for a few hours or so. Precautions should be taken to

avoid direct eye contact with this material. If eye contamination should

occur, the eyes should be flushed with copious amounts of water as soon as

practical.

Single, repeated or prolonged exposures of DOW CORNING* 710 Fluid to the skin

of rabbits produces no observable effect and there are no indications that

this fluid is absorbed through the skin in acutely toxic amounts. No special

precautions appear necessary in order to handle this material safely for skin

exposure.

CLG/kld

2-3-84

DOW CORNING CORPORATION, MIDLAND, MICHIGAN 48640-0994 TELEPHONE 517 496-4000
APPENDIX V

NOMENCLATURE
APPENDIX V

NOMENCLATURE

ASTM American Society for Testing and Materials

CCS Cold-Cranking Simulator

CTM Dow Corning Corporate Test Method

D Polydispersity, M /M

\v a

DSC Differential Scanning Calorimeter

DTA Differential Thermal Analysis

GPC Gel Permeation Chromatography

Hex Hexyl ligand, n-C^H,_-

IR Infrared Spectroscopy

LC Liquid Chromatography

LDR Liquid Droplet Radiator

M Number Average Molecular Weight (p. 1)

M Weight Average Molecular Weight (p. 1}

Me Methyl ligand, CH3-

NMR Nuclear Magnetic Resonance Spectroscopy

0(3p) Atomic oxygen, ground state

P Pressure, Pascals unless stated otherwise

PDMS Polydimethylsiloxane

Ph Phenyl ligand, C_H -

D D

PMPS Polymethylphenylsiloxane

SET Scanning Brookfield Viscometer Technique

T Temperature, Kelvin unless stated otherwise

TBS Tapered Bearing Simulator Viscometer

TGA Thermogravimetric Analysis

USLCV Ubbelohde Suspended Level Capillary Viscometer
I Refers to Fluids isolated in Task I

II Refers to Fluids isolated in Task II

1 Refers to Series 1 evaporation rate data (p. 11)

2 Refers to Series 2 evaporation rate data (p. 11)

704 Tetramethyltetraphenyltrisiloxane

Dow Corning® 704 Fluid

705 Trimethylpentaphenyltrisiloxane

Dow Corning® 705 Fluid

710 . Trimethylendblocked methylphenylsiloxane

Dow Corning® 710 Fluid

Cp Specific heat

AH Heat of vaporization

Y Surface tension

X Thermal conductivity

v Kinematic viscosity

p Density

a Electrical resistivity
1. Report No.

NASA CR-175033

2. Government Accession No. 3. Recipient's Catalog No.

4. Title and Subtitle

Organosiloxane Working Fluids for the Liquid

Droplet Radiator

5. Report Date

December, 1985

6. Performing Organization Code

7. Authors)

R. R. Buch, A. R. Huntress

8. Performing Organization Report No.

10. Work Unit No.

9. Performing Organization Name and Address

Dow Corning Corporation

Midland, MI 48640

11. Contract or Grant No.

NAS3-24400

12. Sponsoring Agency Name and Address

National Aeronautics and Space Administration

Washington, D.C. 20546

13. Type of Report and Period Covered

Contractor Report

14. Sponsoring Agency Code

506-41-5A

15. Supplementary Notes

Final report. Project Manager: K. Alan White,

Power Technology Division, NASA Lewis Research Center,

Cleveland, Ohio 44135

16. Abstract

Siloxane-based working fluids for advanced space radiators requiring direct fluid exposure

to the space environment are.-evaluated. Isolation of five candidate fluids by vacuum

distillation from existing siloxane polymers is discussed. The five fluids recovered

Include a polydimethylsiloxane, three phenyl-containing siloxanes, and a methylhexylsiloxane. Vapor pressures and viscosities for the five fluids are reported over the

temperature range of 250 to 400 K. Use of thermal-gravimetric analysis to reliably estimate

vapor pressures of 10 Pascals is described.

Polydimethylsiloxane (PDMS) and polymethylphenylsiloxane (PMPS) were selected from the five

candidate fluids based on favorable vapor pressure and viscosity, as well as perceived

stability in low-earth orbit environments. Characterization of these fluids by infrared

spectroscopy, Si29 NMR, gel-permeation chromatography, and liquid chromatography is

presented. Both fluids consisted of narrow molecular weight distributions, with average

molecular weights of about 2500 for PDMS and 1300 for PMPS.

Vapor pressure, viscosity, Theological behavior, density, surface tension, specific heat,

thermal conductivity, and electrical conductivity for PDMS and PMPS are presented for the

temperature range 250 to 400 K. Pour point, flash point, and fire point for each fluid are

also reported, as are heats of vaporization calculated from the Clausius-Clapeyron relation.

Emission spectra for the two fluids at 430 K are presented for the infrared region. Transmission spectra in the infrared region are also reported for thin films of several

thicknesses.

Thermal, oxidative, and radiative stability, as well as flammability and toxicity, are

discussed based on results of a search of relevant siloxane literature. Methods for

adjusting viscosity and vapor pressure, and for improving stability in the low-earth

environment, are suggested.

17. Key Words (Suggested by Author(s))

Organosiloxane; Low vapor pressure

fluids; Liquid Droplet Radiator

19. Security Classif. (of this report)

Unclassified

18. Distribution Statement

Unclassified -

STAR Category

20. Security Classif. (of this page)

Unclassified

• unlimited

27

21. No. of pages

166

22. Price*

A08

*For sale by the National Technical Information Service, Springfield, Virginia 22161