NATL INST. OF STAND & TECH

AlllOb TTfl^DD

NBSIR 83-1684

TENSILE, COMPRESSIVE, AND

PROPERTIES OF A 64-kg/m3

POLYURETHANE FOAM AT

LOW TEMPERATURES

J.M. Arvidson

L.L. Sparks

Chen Guobang

National Bureau of Standards

U.S. Department of Commerce

Boulder, Colorado 80303

February 1983

NATIONAL BUREAU

OF STANDARDS

LIBRARY

NBSIR 83-1684

TENSILE, COMPRESSIVE, AND SHEAR

PROPERTIES OF A 64-kg/m3

POLYURETHANE FOAM AT

LOW TEMPERATURES

‘Fracture and Deformation Division

National Measurement Laboratory

“Thermophysical Properties Division

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Boulder, Colorado 80303

fGuest worker at NBS. Department of Thermal Science, Zhejiang University,

Hangzhon, Zhejiang Province, People’s Republic of China

February 1983

Prepared for: Gas Research Institute

8600 West Bryn Mawr Avenue

Chicago, Illinois 60631

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

J.M. Arvidson*

L.L. Sparks**

Chen Guobangt

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

3 Tensile, Compressive, and Shear Properties of a 64-kg/m

Polyurethane Foam at Low Temperatures

J. M. Arvidson, L. L. Sparks, and Chen Guobang

Polyurethane foam, having a density of 64 kg/m 3

, was tested at 295, 111,

76, and 4 K. The material properties reported are Young's modulus,

proportional limit, yield strength (at 0.2% offset), tensile, shear, and

compressive strengths, and elongation (elastic and plastic). To perform these

tests, a unique apparatus was developed. This apparatus permits tension,

compression, and shear testing of materials at any temperature ranging from

295 to 1.8 K. Strain is measured with a concentric, overl apping-cyl inder

capacitance extensometer that is highly sensitive and linear in output.

Key words:

temperatures

;

compressive strength;

mechanical properties;

elongation; foam; insulation; low

proportional limit; shear strength;

tensile strength; yield strength; Young's modulus.

1. INTRODUCTION

Polyurethane foams are used in many structural as well as insulating

applications in which knowledge of material performance in extreme

environments (e.g., at liquefied natural gas, liquid nitrogen, and liquid

helium temperatures ) is essential. Accurate data, predictive capability, and

standardized methods and materials improve the selection and development of

materials for these applications. The mechanical properties reported here are

part of a broader effort to understand and predict the thermal and mechanical

behavior of expanded plastics (foams) in cryogenic environments.

The tensile, compressive, and shear properties of polyurethane foam,

having a density of 64 kg/m 3

, were determined using a test fixture developed

specifically for this program [1]. This fixture provides the capability of

determining the above material properties at any temperature from ambient

(295 K) to 1.8 K. Tests can be done in a cold gaseous atmosphere or in

liquids, such as helium (4 K), nitrogen (76 K), and dry ice and alcohol

(195 K). The fixture has also been designed to test materials at the above

temperatures while under static pressures ranging from subatmospheric to

approximately 0.3 MPa (43.7 psia).

A strain extensometer that was developed for use with soft viscoelastic

materials utilizes concentric overlapping cylinders and the change in electrical

capacitance to detect specimen strain [2]. This type of extensometer does not

attach directly to the specimen, so the effect of instrumentation on the

experimental results is negligible (verified to contribute <2.5 x 10 m for

our specimen geometry). The extensometer works well in cryogenic environments,

is accurate, and is linear for large strains [3,4]. The capacitance extensometer

system designed for this work had a linearity range in excess of 2.5 cm when

used with the current foam specimen geometry (2.9-cm diameter by 9.9-cm length).

1
Similar extensometers can be designed for specific sensitivities and extents

of linearity [5]. As long as the capacitance extensometer is situated in a

stable fluid (i.e., single phase and nonboiling) the resultant is a very high

signal-to-noise ratio. These sensors function in gases as well as in liquids

and the device is only sensitive to the dielectric constant of the test

medium. The original calibration of the system, for example, can be performed

at room temperature in air. To conduct a test in any other medium (e.g.,

liquid nitrogen) the original calibration need only be corrected for the

change in dielectric constant [6].

2. MATERIAL CHARACTERIZATION

The material tested in this study is a nominal 64-kg/m 3 polyurethane foam

designated as GM35. This amorphous organic polymer is a thermosetting foam.

Our supply of this material was obtained from the NBS Office of Standard

Reference Materials (OSRM) in Gaithersburg, Maryland. The OSRM distributed

this and other expanded plastics for the Products Research Committee [7,8].

These materials were commercially produced and designated as General

Material s

.

The bulk supply of GM35 was a 0.1-m x 0.6-m x 0.6-m slab (figure la).

The orientation of the elongated cell axis for the material used in the

physical properties tests was determined optically from statistical evaluation

of photomicrographs . The ratios of cell height to cell width for the

principal orthogonal planes of the physical test specimens were: x/y = 0.94 ±

0.34, z/x = 1.60 ± 0.65, z/y = 1.51 ± 0.58. The uncertainties given represent

estimates of one standard deviation. The cell orientations relative to the

orthogonal axes of the bulk slab are shown in figure lb.

2
The density of this res in- gas composite was found to be 62.22 ± 0.28

kg/m 3

, 62.52 ± 0.11 kg/m 3

, and 62.56 ± 0.13 kg/m 3 after conditioning at 23°C

and 24, 50, and 92 percent relative humidity respectively. The uncertainties

given are estimates of one standard deviation.

3. SPECIMENS

Test specimens taken from the x/y or z/x plane in the bulk supply (see

figure 1) are designated "longitudinal" when loaded parallel to the z direction.

Conversely, specimens taken from the x/y plane and loaded parallel to either

the x or y direction are designated "transverse"

.

The tensile specimens were rods 9.9-cm long and 2.9-cm in diameter. This

specimen was used to determine Young's modulus, proportional limit, yield

strength (at 0.2% offset) , and elongation (extrapolated using ultimate

tensile strength). For the determination of ultimate tensile strength, a

reduced section specimen was used. Its gage length was 5.1 cm and its

diameter was 1.9 cm. All tensile specimens were epoxied to polycarbonate

grips, which were threaded to accomodate the tensile pull-rod system. The

reduced-section geometry forced fracture to occur within the gage length,

thereby eliminating the effect of biaxial stresses at the grip ends.

The compression specimens were 2.54-cm long and 2.9-cm in diameter.

These specimens did not require grips.

Shear specimens were 1.9 cm x 2.54 cm x 0.4 cm. The specimens were

epoxied to two flat plates and each plate was attached to the upper and lower

tensile pull-rod system, respectively. An aluminum cylinder was slipped over

the specimen and plates to help maintain alignment and minimize induced torque

during testing. In addition, the cylinder has a built-in resistive heater

that is controlled by a thermocouple to produce and maintain the desired test

temperature.

3
4. TEST PROCEDURES

Most tests were conducted at 295 K(air), 111 K(gaseous helium), 76 Illiquid

nitrogen), and 4 K (liquid helium). To minimize thermal shock to the specimen,

the liquid helium or nitrogen was transferred at a very slow rate. The tensile

and compressive properties included: Young's modulus, proportional limit,

yield strength (at 0.2 percent offset), tensile and compressive strengths, and

elongation (elastic and plastic).

Since an ASTM shear strength test method is not available for soft

cellular materials such as these foams, several methods were carefully considered, and a version of the guil lotine-type shear test was selected. Many

specimen geometries (thicknesses and widths) were tested to find the best

combination that most consistently failed in shear. At least three tests were

conducted at each temperature; in some cases, more tests were run to determine

material variability. Prior to testing, all specimens were "conditioned" in

an environmental chamber for not less than four days at 23°C and 50 percent

relative humidity. Each specimen was tested shortly after removal from the

environmental chamber. All tests were conducted in a conventional compression/

tension test machine at a strain rate of 5 x 10 min . (Varying the rate -4-2-1 x from 5 x 10 to 5 x 10 min had no measurable effect on results.)

5. RESULTS

Results are presented in figures 2 through 15 and tables 1 through 6.

The bars on the figures indicate the data spread from replicate tests.

Scatter is typically higher for compression and shear than for tensile tests;

this is because the compressive and shear tests are more sensitive to problems

such as misalignment (tensile specimens self-align during the test). Unlike

the 32-kg/m 3 foam that was tested previously [1], the cell orientation of the

64-kg/m 3 material agreed very well with the bun-line orientation

4
(i.e., the vertical or "rise" direction is denoted as longitudinal). Tensile

results shown in figures 2 through 6 are Young's modulus, ultimate strength,

and strain-versus- temperature, as well as stress-versus-strain curves for all

temperatures. In addition to the above properties, compressive results

include yield strength (at 0.2% offset), proportional limit versus temperature,

and a typical load-versus-displacement curve, as shown in figures 7 through

14. The shear results are given in figure 15.

Tensile, Young's modulus, proportional limit, yield strength, ultimate

strength, and shear strength values all increase as temperature decreases from

295 K to 4 K. The longitudinal orientation results have the highest values.

As shown in figure 4, tensile strain decreases with temperature, and the

material becomes brittle at temperatures below 111 K. The compressive Young's

modulus versus temperature, as shown in figure 7, indicates a decrease in mean

values from 111 K to 76 K, for both longitudinal and transverse specimens.

The same behavior was also noted for a 32-kg/m 3 polyurethane foam material

that was previously tested [1], Using the Student's "t" test for small sample

size, the longitudinal and transverse compressive data were calculated for 76

and 111 K. The results indicate a level of confidence of >99.95% for the

transverse and 88% for longitudinal tests that the mean compressive modulus at

76 K is lower than the mean compressive modulus at 111 K [9]. Figure 11

indicates a deformation capability during compression at low temperatures.

However, since the polyurethane material is incapable of true plastic

deformation at cryogenic temperatures, this apparent plastic strain is caused

by individual cells that collapse during testing. Figures 12 and 13 show the

stress-versus-strain behavior of longitudinal and transverse specimens at 295,

111, 76, and 4 K. Figure 14 is an actual record of load-versus-displacement

for a typical specimen. The load drops illustrate points

5
at which individual or multiple cells fail under stress. Owing to material

variability, the stress-strain graphs were plotted as smooth curves, which do

not show the cell failure phenomena. Each stress-strain curve, at a given

temperature and orientation, is the average of three or more specimens tested.

6. DISCUSSION

Polyurethane foam behavior is typical of polymers in general, with large

mechanical property changes such as a complete loss of ductility and a doubling

of Ej (Young's modulus-tension) following a temperature reduction from 295 K

to 4 K. Certain longitudinal properties, like shear strength and E^ (Young's

modulus-compression), exhibit maximum values between the two extreme

temperature limits; however this is probably not a true material behavior but

an effect influenced by material variability and orientation irregularities.

The anomalous behavior of compressive Young's modulirs as shown in figure 7

appears to be a real effect. As stated previously, the 32-kg/m 3 polyurethane

foam tested exhibited the same drop in modulus from 111 to 76 K. In addition,

a third density of polyurethane foam (96-kg/m 3

) has recently been tested and

it shows the same trend.

Sectioning after testing revealed that cell orientation varied slightly

from the orientation of the mold axes (see figure 1). It is generally thought

that foam specimens from the center of a large billet have uniform cells

oriented with respect to the vertical, but this is not true of foams formed on

a continuous or bun-line production facility. The cell orientation reflects

the movement of the foaming resin. However, as shown in this higher density

foam, the problem of cell orientation with respect to vertical is not as

severe as with less dense materials. Cells in the x-z plane of the material

reported here have only a 86 to 87° inclination to the x-axis (figure 1).

6
Specimens tested previously in liquid nitrogen [1] appeared to have

slightly lower shear strength values than those tested at the same temperature

in cold helium gas. This may be an indication of environmental sensitivity.

Nitrogen at low temperatures is deleterious to a number of other polymeric

materials. Thermoplastics have exhibited crazing or reduced fracture strengths,

or both when tensile tested in cold liquid or gaseous nitrogen, but not in

vacuum or helium environments [10]. Environmental effects must ultimately be

taken into account in design applications.

The authors are indebted to Robert S. Bell and Ronald D. Kriz for their

assistance in the preparation of this manuscript for publication.

References

[1] J. M. Arvidson and L. L. Sparks, "Low Temperature Mechanical Properties

of a Polyurethane Foam", NBSIR 81-1654, National Bureau of Standards,

Boulder, Colorado (November, 1981).

[2] R. P. Reed, J. M. Arvidson, and R. L. Durcholz, Tensile properties of

polyurethane and polystyrene foams from 76 to 300 K, in: "Advances in

Cryogenic Engineering," Vol . 18, K. D. Timmerhaus, ed., “Plenum Press, New

York (1973), pp. 184-193.

[3] J. M. Roberts, R. B. Herring, and D. E. Hartman, The use of capacitance

gauge sensors to make precision mechanical property measurements, jm:

"Materials Technology," American Society for Mechanical Engineers, New

York (1968), pp. 87-96.

[4] "High-Temperature Capacitive Strain Measurement System," NASA Tech. Brief

B75- 10069, NASA (1975).

[5] P. C. F. Woldendale, Capacitive displacement transducers with high

accuracy and resolution, J. Sci. Instrum. ( J. Phys. E) 1:817 (1968).

[6] G. R. White, Measurement of thermal expansion at low temperatures,

Cryogenics , 2:151 (1961).

[7] "Materials Bank Compendium of Fire Property Data," Products Research

Committee, J. W. Lyons, chairman. National Bureau of Standards,

Washington, D.C. (1980).

[8] W. G. Jurevic, "Structural Plastics Applications Handbook Supplement 1 Test Methods," Technical Report AFML-TR-67-332 (1969).

7
[9] J. W. Dally, Statistical treatment of experimental data, Experimental

Mechanics 19(11) : 42 1 (1979).

[10] A. Hiltner and E. Baer, Mechanical properties of polymers at cryogenic

temperatures, Polymer 15:805 (1974).

3
List of Figures

Figure 1(a). Bulk supply of bun-line-produced, 64-kg/m 3 polyurethane foam.

(b). Cell orientation relative to the major coordinate axes of the

bulk supply.

Figure 2. Tensile Young's modulus versus temperature.

Figure 3. Ultimate tensile strength versus temperature.

Figure 4. Tensile strain versus temperature.

Figure 5. Tensile stress versus strain (longitudinal orientation).

Figure 6. Tensile stress versus strain (transverse orientation).

Figure 7. Compressive Young's modulus versus temperature.

Figure 8. Compressive strength versus temperature.

Figure 9. Compressive proportional limit versus temperature.

Figure 10. Compressive yield strength versus temperature.

Figure 11. Compressive strain versus temperature.

Figure 12. Compressive stress versus strain (longitudinal orientation).

Figure 13. Compressive stress versus strain (transverse orientation).

Figure 14. Compressive load versus displacement (transverse orientation).

Figure 15. Shear strength versus temperature (longitudinal and transverse).

List of Tables

Table 1. Tensile test results for a 64-kg/m 3 polyurethane foam.

Table 2. Compressive test results for a 64-kg/m 3 polyurethane foam.

Table 3. Shear strength test results for a 64-kg/m 3 polyurethane foam.

Table 4. Summary of tensile test results for a 64-kg/m 3 polyurethane foam

(average values).

Table 5. Summary of compressive test results for a 64-kg/m 3 polyurethane foam

(average values).

Table 6. Summary of shear strength test results for a 64-kg/m 3 polyurethane

foam (average values).

9
a)

z

®y

X

b)

Figure

ht* ff7

* z

1 1 1 / / /

ox

86^ 00

1 M

X®

y

z

L - .. - . J 1 m

1(a). Bulk supply of bun-line-produced, 64-kg/m3 polyurethane foam.

(b). Cell orientation relative to the major coordinate axes of the

bulk supply.

10
YOUNG'S

MODULUS,

MPR

12.5

10.0

7.5

5.0

2.5

0.0

0

11

YOUNG'S

MODULUS,

KS
TENSILE

STRENGTH,

MPfl

TEMPERRTURE,

Figure 3. Ultimate tensile strength versus temperature.

12

TENSILE

STRENGTH,

PS
TENSILE

STRAIN,

X

15.0

12. 0

-

8. 0

-

8. 0

-

3. 0

-

Total

13
STRESS,

MPfl

Figure 5. Tensile stress versus strain (longitudinal orientation).

14

STRESS,

PS
STRESS,

MPfl

15

STRESS,

PS
YOUNG

1S

MODULUS,

MPfl

150.0

120. 0

-

90.0

60. 0

-

30. 0

-

0.0

J I I L

- 20.0

0.0 50.0 100.0 150.0 200.0

TEMPERRTURE,

250.0 —h 0.0

300.0

Figure 7. Compressive Young's modulus versus temperature.

16

YOUNG'S

MODULUS,

KSI
COMPRESS

I

VE

STRENGTH,

MPR

Figure 8. Compressive strength versus temperature.

17

CONPRESS

I

VE

STRENGTH,

PS
PROPORT

I

ONRL

LIMIT,

MPfl

TEMPERATURE,

Figure 9. Compressive proportional limit versus temperature.

18

PROPORTIONAL

LIMIT,

PS

I
YIELD

STRENGTH

(fiT

0.2%

OFFSET

),MPR

- 150.0

100.0

- 50.0

19

YIELD

STRENGTH

(AT

0.2%

OFFSET),

PSI
COMPRESSIVE

STRAIN,

20
STRESS,

MPR

STRAIN

Figure 12. Compressive stress versus strain (longitudinal orientation).

21

STRESS,

PS

I
STRESS,

MPfl

STRAIN

Figure 13. Compressive stress versus strain (transverse orientation).

22

STRESS,

PS
LOflD/KN

100.0

75.0

50.0

25.0

0.0

Figure 14. Compressive load versus displacement (transverse orientation).

23

LORD,

LB
SHEAR

STRENGTH,

MPfl

TEMPERRTURE,

K

Figure 15. Shear strength versus temperature (longitudinal and transverse).

24

SHEAR

STRENGTH,

PS

I
Table 1. Tensile test results for a 64-kg/m 3 polyurethane foam

Specimen

number

Test

temp.

,

K

Specimen Young's

orientation 3 MPa

modul us

,

psi

Proportional limit,

MPa psi

Yield strength

(at 0.2% offset)

MPa psi

Ultimate tensile

strength

MPa psi

Tensile strain, %

Elastic Plastic Total

2LT.1LRT 295 L 31 .63 4587 0.304 44.09 0.572 82.96 1.027 148.95 3.1 2.8 5.9 4LT.3LRT 295 L 32.13 4660 0.315 45.68 0.602 87.31 0.957 138.79 3.1 2.8 5.9 6LT,5LRT 295 L 29.51 4280 0.338 49.02 0.636 92.24 1.000 145.03 3.1 3.9 7.0

x = 31.09 4509 0.319 46.26 0.603 87.50 0.995 144.26 3.1 3.2 6.3 2TT.1TRT 295 T 14.59 2116 0.156 22.63 0.262 38.00 0.639 92.67 4.5 5.8 10.3 4TT.3TRT 295 T 14.00 2030 0.145 21 .03 0.252 36.55 0.662 96.01 4.6 6.7 11.3 10TT.9TRT 295 T 14.08 2042 0.171 24.80 0.262 38.43 0.638 92.53 4.6 5.5 10.1

x = 14.22 2063 0.157 22.82 0.260 37.66 0.646 93.74 4.6 6.0 10.6 22LT.15LRT 111 L 58.80 8528 - - - - 1.204 174.61 1 .9 0 1.9 24LT.17LRT 111 L 58.75 8521 - - - - 1 .041 150.98 1 .9 0 1.9 34LT.21LRT 111 L 60.20 8730 - - - - 1.101 159.68 1.7 0 1.7

i = 5972F M - - - - 1.115 161.76 T3 U T3

24TT.19TRT 111 T 25.58 3710 . - - . 0.637 92.38 2.4 0 2.4 26TT.23TRT 111 T 25.84 3748 - - - - 0.611 88.61 2.3 0 2.3 42TT.25TRT 111 T 26.63 3862 - - . - 0.573 83.10 2.3 0 2.3

x = 20? 3774" - - - - 0.607 88.03 23 7 73

8LT.9LRT 76 L 64.97 9423 - - - - 1.136 164.75 1 .9 0 1.9 12LT.11LRT 76 L 60.80 8818 - - - - 1.286 186.51 1 .8 0 1.8 14LT.13LRT 76 L 63.91 9269 - - - - 1.247 180.85 1 .9 0 1.9

x = 63.23 9170 - - - - 1.223 177.37 1.9 0 1.9 12TT.11TRT 76 T 27.82 4035 - - - - 0.750 108.77 2.6 0 2.6 14TT.13TRT 76 T 28.31 4106 - - - - 0.723 104.86 2.6 0 2.6 16TT.17TRT 76 T 27.68 4014 - - - - 0.721 104.57 2.6 0 2.6

x = 27.94 4U5? - - - - 0.731 106.0? 73 7 73

16LT.19LRT 4 L 78.14 11333 - - - - 1.172 169.97 1.5 0 1.5 18LT.23LRT 4 L 75.78 10990 - - - - 1.242 180.13 1.5 0 1.5 32LT.25LRT 4 L 74.26 10770 - - - - 1.149 166.64 1 .6 0 1.6

x = 706 11031 - - - - 1.188 172.25 1.5 0 1.5 18TT.15TRT 4 T 33.19 4814 . - . - 0.702 101 .81 2.0 0 2.0 20TT.27TRT 4 T 32.99 4785 - - - - 0.641 92.96 2.0 0 2.0 30TT.31TRT 4 T 31.54 4574 - - - - 0.662 96.01 2.1 0 2.1

x = 32.57 4724 - - - - 0.668 96.93 2.0 0 2.0

a L: longitudinal; T: transverse

25
Table 2. Compressive test results for a 64-kg/m3 polyurethane foam

Specimen Test Specimeni Young's modul us

,

Proportional limit. Yield strength Maximum compressive Compressive

number temp.

,

orienta- (at 0.2% offset). strength, strain. %

K tiona MPa psi MPa psi MPa psi MPa psi Elastic Plastic Total

26LC (A) 295 L 23.08 3347 0.355 51.49 0.498 72.22 0.668 96.88 2.8 2.8 5.6 26LC (B) 295 L 20.37 2954 0.405 58.74 0.482 69.90 0.668 96.88 3.2 3.4 6.6 28LC (B) 295 L 21.63 3137 0.382 55.40 0.504 73.10 0.680 98.62 3.0 4.4 7.4

x = 21.69 3146 0.381 507 095 77777 0.672 97779 93 93 93

32TC (A) 295 T 7.86 1140 0.121 17.55 0.222 32.20 0.360 52.21 4.4 3.1 7.5 32TC (B) 295 T 8.30 1204 0.136 19.72 0.219 31.76 - a

- - - - 38TC (A) 295 T 7.95 1153 0.174 25.24 0.270 39.16 0.378 54.82 4.5 2.6 7.1

; = 04 7799 97f7? 20.84 037 34.37 07369 53 . 52 779 93 73

28LC (A) 111 L 105.81 15346 0.715 103.70 0.817 118.49 1 .078 156.34 1.0 8.4 9.4 28LC (B) 111 L 87.19 12645 0.664 96.30 0.823 119.36 1 .063 154.17 1.2 10.5 11.7

30LC (A) 111 L 88.72 12867 0.657 95.28 0.792 114.86 1.121 162.58 1.3 8.3 9.6

* = 93.91 79979 0.679 98.43 9.81) 1 T7 . 57 1 .087 157.70 772" 93 793

40TC (B) 111 T 30.07 4361 0.389 56.42 0.482 69.90 0.734 106.45 2.4 9.9 12.3

40TC (C) 111 T 30.07 4361 0.362 52.50 0.409 59.32 0.722 104.71 2.3 10.7 13.0 47TC (A) 111 T 33.46 4853 0.334 48.44 0.378 54.82 0.730 105.87 2.1 8.0 10.1

x

= "31720 4525 062 52.45 0.423 61 .35 97729 105.68 73 93 773

31 LC (A) 76 L 85.13 12346 0.846 122.70 0.970 140.68 1.179 170.99 1 .4 7.7 9.1 31LC (B) 76 L 87.77 12729 0.873 126.61 0.962 139.52 1.160 168.23 1 .3 8.2 9.5

31 LC (C) 76 L 82.03 11897 0.753 109.21 0.897 130.09 1.131 164.03 1 .4 7.2 8.6

x = 8479$ 7232? 027 119.51 97973 795779 77797 797779 777 777 93

38TC (A) 76 T 16.80 2436 0.376 54.53 0.552 80.06 0.792 114.86 4.6 5.9 10.5

38TC (B) 76 T 17.72 2570 0.341 49.46 0.537 77.88 0.792 114.86 4.4 7.6 12.0 49TC (A) 76 T 16.85 2444 0.349 50.62 0.539 78.17 0.781 113.27 4.5 7.3 11.8

x = 17.12 1483 055 57757 97573 709 97788 777799 73 93 7777

33LC (A) 4 L 79.55 11537 0.765 110.95 0.897 130.09 1.156 167.65 1.5 5.9 7.4 33LC (B) 4 L 53.17 7711 0.850 123.28 0.955 138.50 1 .183 171.57 2.2 7.4 9.6

33LC (C) 4 L 99.43 14420 0.846 122.70 0.947 137.34 1.210 175.49 1.2 8.7 9.9 35LC (A) 4 L 137.69 19969 - 0.765 110.95 1.206 174.91 0.9 8.5 9.4

x = 92.46 13M 02? 118.98 97S9T 129.32 77799 772777 1 .5 7.6 93

35TC (B) 4 T 43.48 6306 0.294 42.64 0.387 56.13 0.807 117.04 2.1 8.4 10.5 48TC (A) 4 T 46.29 6713 0.475 68.89 0.579 83.97 0.850 123.28 2.0 14.3 16.3 49TC (B) 4 T 45.17 6551 - - - - 0.838 121.53 - - - x = 44.98 6523 0.384 55.77 0.483 70.05 0.832 120.62 2.0 11.4 13.4

Stress continued to increase as strain increased - no maximum reached.

26
Table 3. Shear strength test results for a 64-kg/m 3 polyurethane foam

Specimen

number

Test

temperature,

K

Specimen

orientatior

Shear strength,

MPa psi

SL4 295 L 0.428 61 .99

SL6 295 L 0.581 84.19

SL7 295 L 0.514

x = 0.508

74.53

73.57

ST6 295 T 0.681 98.68

ST7 295 T 0.661 95.90

ST8 295 T 0.663

x = 0.668

96.19

96.92

SL1

111 L 0.697 101.01

SL1

111 L 0.728 105.54

SL1 3 111 L 0.694

x = 0.706

100.67

102.41

ST1111 T 0.704 102.09

ST1

111 T 0.729 105.65

ST1111 T 0.791

x = 0.741

114.67

107.47

SL1 76 L 0.727 105.38

SL2 76 L 0.739 107.13

SL3 76 L 0.705

x = 0.724

102.23

104.91

ST4 76 T 0.821 119.07

ST9 76 T 0.546 79.19

ST1

76 T 0.759

x = 0.709

110.00

102.75

SL8 4 L 0.612 88.70

SL9 4 L 0.691 100.18

SL1

4 L 0.712

x = 0.672

103.20

97.36

ST1 4 T 0.909 131.78

ST3 4 T 0.739 107.08

ST5 4 T 0.975

x = 0.874

141 .37

126.74

27
Table 4. Summary of tensile test results for a 64-kg/m3 polyurethane foam (average values)

Material

property

Specimen

orientation 295 K Temperature111 K 76 K 4 K

Young ' s L 31.09 (4,510) 59.25 (8,590) 63.23 (9,170) 76.06 (11,030)

modulus

MPa (psi)

T 14.22 (2,060) 26.02 (3,770) 27.94 (4,050) 32.57 ( 4,720)

Proportional L 0.319 (46.26) - - - limit, MPa (psi) T 0.157 (22.82)

Yield strength L 0.603 (87.50) - . -

( 0 . 2 % Offset),

MPa (psi)

T 0.260 (37.66)

Ultimate ten- L 0.995 (144.26) 1.115 (161.76) 1.223 (177.37) 1.188 (172.25)

sile strength,

MPa (psi)

Tensile strain,

T

%

0.646 ( 93.74) 0.607 ( 88.03) 0.731 (106.07) 0.668 ( 96.93)

Elastic L 3.1 1 .8 1 .9 1 .5 Plastic 3.2 0 0 0 Total 6.3 1 .8 1 .9 1.5

Elastic T 4.6 2.3 2.6 2.0 Plastic 6.0 0 0 0 Total 10.6 2.3 2.6 2.0

Table 5. Summary of compressive test results for a 64-kg/m 3 polyurethane foam (average values)

Material Specimen Temperature

property orientation 295 K 111 K 76 K 4 K

Young's L 21.69 (3,150) 93.91 (13,620) 84.98 (12,320) 92.46 (13,410)

modul us

MPa (psi) T 8.04 (1,170) 31.20 ( 4,530) 17.12 ( 2,480) 44.98 ( 6,520)

Proportional L 0.381 (55.21) 0.679 ( 98.43) 0.824 (119.51) 0.820 (118.98)

1 imit, MPa (psi) T 0.143 (20.84) 0.362 ( 52.45) 0.355 ( 51.54) 0.384 ( 55.77)

Yield strength L 0.495 (71.74) 0.811 (117.57) 0.943 (136.76) 0.891 (129.22)

(0.2% Offset),

MPa (psi) T 0.237 (34.37) 0.423 ( 61.35) 0.543 ( 78.70) 0.483 ( 70.05)

Maximum compres- L 0.672 (97.46) 1.087 (157.70) 1.157 (167.75) 1.189 (172.41)

sive strength,

MPa (psi)

T 0.369 (53.52) 0.729 (105.68) 0.788 (114.33) 0.832 (120.62)

Compressive strain. % Elastic L 3.0 1 .2 1 .4 1.5 Plastic 3.5 9.0 7.7 7.6

Total 6.5 10.2 9.1 9.1

Elastic T 4.5 2.3 4.5 2.0 Plastic 2.8 9.5 6.9 11.4

Total 7.3 11.8 11.4 13.4

28
Table 6. Summary of shear strength test results for a 64-kg/m3 polyurethane foam (average values)

Test

temperature, K Specimen orientation Shear

MPa

strength,

psi

295 L 0.508 73.57

T 0.668 96.92

111 L 0.706 102.41

T 0.741 107.47

76 L 0.724 104.91

T 0.709 102.75

4 L 0.672 97.36

T 0.874 126.74

29
NBS-114A jREV. 2-80

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO. NBSIR 83-1684

2. Performing Organ. Report No 3. Publication Date February 1983

4. TITLE AND SUBTITLE

Tensile, Compressive, and Shear Properties of a 64 -kg/m Polyurethane Foam at

Low Temperatures

5. AUTHOR(S)

J. M. Arvidson, L. L. Sparks, and Chen Guobang

6 . PERFORMING ORGANIZATION (If joint or other than N BS, see instructions) 7 . Contract/Grant No. national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

8

.

Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State, ZIP)

Gas Research Institute

8600 West Bryn Mawr Ave.

Chicago, IL 60631

10.

SUPPLEMENTARY NOTES

/ ] Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant in formation . If document includes a si gn i fi cant bibliography or literature survey, mention it here) Polyurethane foam, having a density of 64-kg/m , was tested at 295, 111, 76, and 4 K

The material properties reported are Young's modulus, proportional limit, yield

strength (at 0.2% offset), tensile, shear, and compressive strengths, and elongation

(elastic and plastic). To perform these tests, a unique apparatus was developed. This

apparatus permits tension, compression, and shear testing of materials at any temperatu

ranging from 295 to 1.8 K. Strain is measured with a concentric, overlapping-cylinder

capacitance extensometer that is highly sensitive and linear in output.

:e

12. KEY WORDS (Six to twelve entries; alphabetical order; capi ta 1 i ze only proper names; and separate key words by semi colon s) compressive strength; elongation; foam; insulation; low temperatures ; mechanical

properties; proportional ]imit; shear strength; tensile strength; yield strength;

13: avATl Ability

[»[] Unlimited

[~'

'j For Official Distribution. Do Not Release to NTIS

1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

[X Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

33

15. Price$8.50

SPO 838 - 872 USCOMM-DC 8043-P80


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