NATIONAL BUREAU OF STANDARDS REPORT

8660

Ifftt for ^ to retomo? 1

MODIFIED BLOWING OF ASPHALTS

by

Sidney H. Greenfeld

<NBS>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards is a principal focal point in the Federal Government for assuring

maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. Its responsibilities include development and maintenance of the national stand- ards of measurement, and the provisions of means for making measurements consistent with those standards; determination of physical constants and properties of materials; development of methods

for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of standard practices for incorporation in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; assistance

to industry, business, and consumers in the development and acceptance of commercial standards and

simplified trade practice recommendations; administration of programs in cooperation with United

States business groups and standards organizations for the development of international standards of

practice; and maintenance of a clearinghouse for the collection and dissemination of scientific, technical, and engineering information. The scope of the Bureau’s activities is suggested in the following

listing of its four Institutes and their organizational units. Institute for Basic Standards. Electricity. Metrology. Heat. Radiation Physics. Mechanics. Applied Mathematics. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radio Standards Laboratory: Radio Standards Physics; Radio Standards Engineering.** Office of Standard Ref- erence Data. Institute for Materials Research. Analytical Chemistry. Polymers. Metallurgy. Inorganic Materials. Reactor Radiations. Cryogenics.** Office of Standard Reference Materials. Central Radio Propagation Laboratory.** Ionosphere Research and Propagation. Troposphere

and Space Telecommunications. Radio Systems. Upper Atmosphere and Space Physics.

Institute for Applied Technology. Textiles and Apparel Technology Center. Building Research.

Industrial Equipment. Information Technology. Performance Test Development. Instrumentation.

Transport Systems. Office of Technical Services. Office of Weights and Measures. Office of Engineering Standards. Office of Industrial Services.

* NBS Group, Joint Institute for Laboratory Astrophysics at the University of Colorado. ** Located at Boulder, Colorado.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

421 .04-12-4210141 1 April 1965

MgSiBSHOT Of^

8660

HOT WQ*

MODIFIED BLOWING OF ASPHALTS

by

Sidney H. Greenfeld

Research Associate

Asphalt Roofing Industry Bureau

Organic Building Materials Section

Building Research Division

Institute for Applied Technology

Sponsored by

Asphalt Roofing Industry Bureau

NATIONAL BUREAU OF ! for use within the Governmenj

and review. For this reason, whole or in part, is not autl Bureau of Standards, Washin

the Report has been specifica

IMPORTANT NOTICE

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015.

;ress accounting documents intended

is subjected to additional evaluation

re listing of this Report, either in the Office of the Director, National by the Government agency for which

I copies for its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

MODIFIED BLOWING OF ASPHALTS

Sidney H. Greenfeld

ABSTRACT

The effects of blowing under reflux conditions or pressure and

in the presence of oxygen, chlorine, or sulfur on the properties

of coating-grade roofing asphalts were studied. Refluxing the

volatilized and entrained oils tended to decrease the blowing

losses and to improve the softening point-penetration relationships

and the durabilities of asphalts produced from three fluxes.

Pressure of 25 psig during blowing had mixed effects on the blowing

times and physical properties of the asphalts, but increased their

durabilities. The enrichment of the blowing air with 25 percent

oxygen or 10 percent chlorine (without changing the total gas

volume) greatly accelerated the blowing and improved the physical

properties of the asphalts produced from four fluxes. Durabilities

were also appreciably increased. On the other hand, five percent

sulfur in conjunction with the blowing air or sulfur alone tended

to decrease the durabilities of the asphalts and lower their

penetrat ions . Sulfur did, however, accelerate the hardening

reactions above 400°F (200°C). Only small percentages of the

sulfur or chlorine used remained in the asphalts produced.

1 . INTRODUCTION

Many methods exist for modifying the blowing process used to produce coatinggrade roofing asphalts. This report will discuss two process variables

and three oxidants in addition to air. The process variables were blowing

under reflux conditions and under pressure; the oxidants were oxygen,

chlorine, and sulfur.

In an earlier publication by Murayama (I)—, he reported that when all of

the volatilized and entrained oils were refluxed during the blowing of an Arabian flux, the softening point-penetration relationships were independent of air rate, air volume, and reaction temperature. Although Arabian

1 /

Numbers in parentheses refer to references tabulated in the bibliography.

asphalts are not used alone in this country for roofing purposes, they have

been employed with some success as blending stocks. The differences en- countered in their processing and weathering are related to their relatively paraffinic nature. The results reported by Murayama (1) may not

be pertinent to the naphthenic and aromatic base stocks more customarily

used

.

Both Ghelton, Traxler and Romberg (2) and Levinter and Galiakbarov (3)

have reported that blowing under pressure reduced the blowing time and

improved the rheological properties of asphalts. The former worked with

both Louisiana and Texas fluxes; the latter, with a Tuimazy (Russia)

flux. Ghelton, et al, blew their fluxes to, and in some instances beyond,

the coating-grade range. Levinter and Galiakbarov stopped short of

coating-grade

.

A number of investigators have reported on the use of oxygen, either alone

or in addition to air, for blowing asphalt (4, 5, 6). Patents have been

issued (7), in which its use to accelerate the blowing reaction alone and

with catalysts has been claimed. Graham, et al (4) reported that irrespective of whether oxygen or air was used, only a small part of the oxygen

used remained in the asphalt and the ratio of oxygen consumed to that

supplied was constant. The apparatus, however, was very inefficient and

only about one and a half percent of the oxygen was consumed. Campbell

and Wright (6) reported that the softening point increase on blowing was much more rapid with oxygen than with air. Examination of their Figure 1 shows this increase to be of the order of seven fold. Graham, et al (4)

reported in a similar vein that at normal blowing temperatures it required

only one-third of the time to reach a given penetration when oxygen was used that it did with air.

Pfeiffer (8) reported on hardening of asphalt with chlorine or sulfur.

Both of these agents performed in a manner similar to oxygen; that is,

the asphalt hardened, only a small percentage of the additive remained

in the asphalt and the major portion of the additive escaped from the

asphalt as a reaction product with hydrogen. From the data presented,

it appeared that the Venezuelan asphalt blown with chlorine was quite

similar to the one blown with air. However, Pauer and Haruni (9) reported

that when chlorine mixed with air was used to blow an asphalt flux from

a mixed base Egyptian crude, the rate of reaction increased as the

chlorine content increased (to 4 percent) and the softening point-penetration relationships were modified. Unfortunately the runs were made

for periods of six hours. The products had widely different properties

and were difficult to compare. In all instances where products had

softening points in the vicinity of 220°F, less than one percent chlorine

remained in the asphalts.

3

-

Sanderson (10) blew asphalt with dry chlorine at 300°F (150°C) (to favor

addition instead of substitution reactions) until hydrochloric acid was

evolved. Under these conditions the penetration decreased, the softening

point increased and the resistance to hardening (on exposure to oxygen under

pressure) increased. All of these asphalts were paving-grade materials.

A number of patents have been issued on the use of chlorine in conjunction

with air to oxidize asphalts and oils (11). These claim chlorine improves

the temperature susceptibility of asphalts when used in low concentrations.

Pfeiffer (8) reported that when 5-10 percent of sulfur was added to an asphalt flux at 350-400°F (180-2Q0 o C) perceptible reaction occurred, with

the liberation of hydrogen sulfide. About a third of the sulfur used re- mained in the asphalt. The penetrations were lowered as the softening

point was increased. However, the specific effects varied with the

asphalt source. No information was presented on the use of sulfur in

conjunction with air.

Sulfur was used rather extensively at one time to harden asphalts and

improve their temperature susceptibility. The products were known as Dubbs asphalt, Ventura Flux or Pittsburgh Flux (12). The advent of

air blowing has displaced these processes for economic reasons in the

United States, but sulfur is still used in parts of Europe. A critical

review and evaluation of the relative merits of sulfur in asphalts was made by Marten (13) in 1961. The reported results in the literature were rather inconclusive and highly speculative as far as durability

was concerned. A literature review and bibliography of the use of

sulfur in bitumens has been published by the Sulfur Institute (14).

The most recent publication (15) on the use of sulfur to harden asphalts

relates to its distribution in the asphalt components.

2. MATERIALS AND METHODS

The fluxes used in this study are described in Table I. The blowing

characteristics of the soft fluxes were discussed earlier (16). The

properties of asphalts produced from all of these fluxes both with and

without blowing additives have also been reported (17).

- 4 -

TABLE I.

ASPHALT FLUXES

California Kansas Talco Tia. Juana

Flux Coastal Soft Hard Soft Hard Soft!/ Hard

Softening Point, °F 122 101 120 104 120 104 1 1 1 Penetration at 32°F, 0.1 mm 20 42 18 44 27 44 25

Penetration at 77°F, 0.1 mm 64 249 80 190 92 152 91

Penetration at 115°F, 0.1 mm TSZ/ TS TS TS TS 222 232

Specific Gravity at 77°F 1.030 0.994 1 ,004 1 .020 1 „022 1 .004 1 .011

Flash Point. (C.O.C.), °F 460 635 645 555 560 575 620

Asphaltenes, 7> 30.7 19.3 24,9 26.7 28.1 23.4 20.8

Sulfur, % 5.6 1 .4 1.4 4.6 4.8 2.9 3.1

1/

Partially blown.

2 /

Too soft.

The blowing stills described in reference (16) were modified to accom- modate the special requirements for each phase of this study.

For the refluxing work, a water-cooled, straight copper tube (7/16 in.

inside diameter by 21 -in. long) was used as a condenser on the vapor

exhaust from the still. Substantially all of the condensable material

in the exhaust gases was drained back into the still by this condenser.

When the asphalts were blown under pressure, a throttling valve was

put on the exhaust from the still to control the back pressure at the

desired level. The flow rate was corrected to provide the reported

volume of gas at standard conditions.

Oxygen or chlorine gas was passed directly into the apparatus from its

respective gas cylinder through a rotameter. It was blended with metered

air before entering the still. When oxygen was used the exhaust gases were vented directly into the hood, but when chlorine was used they were percolated through a dilute sodium hydroxide solution to dispose of the

hydrochloric acid generated and any unreacted chlorine. No noticeable

odors of chlorine or hydrochloric acid were apparent in the exhaust of

the absorber.

- 5

-

Flowers of sulfur were blended into the asphalt fluxes below 350°F (177°C)

with the aid of a laboratory stirrer prior to adding the flux to the blowing still. In this temperature range, no evolution of gases was evident.

However, at temperatures above 400°F (200°C) gas was exhausted from the

still whether or not air was being introduced. The gases were percolated

through a sodium hydroxide solution before being exhausted in a hood,

A faint odor of hydrogen sulfide always persisted over the caustic

solution.

In the determinations in which sulfur was used alone, a weighed quantity

of flowers of sulfur was stirred slowly into about 300 grams of asphalt

in a pint can on a thermostated hot plate. The first series was maintained at approximately 430°F (220°C) until a coating-grade softening

point was obtained. At this temperature, the reaction was extremely

violent and the softening point rise very rapid, as shown in Table II„

TABLE II.

EFFECT OF SULFUR ON ASPHALT AT 430°F (220°C)

Asphalt Sulfur

%

Final SP

° F

Reaction Time

Min.

California 5 217 83

California 7 219 81

California 9 219 80

California 10 222 80

Penetrations could not be determined on these asphalts because they were

quite foamy and reaction continued whenever they were heated sufficiently

to start breaking the foam. Consequently, nothing further was done with

this set.

A second series of runs was made with the object of finding the concen- tration of sulfur required to harden each flux to a coating-grade

softening point and no higher. The temperature was reduced to the

375“400°F (190~205°C) range to slow the reaction and reduce the foaming.

At these lower temperatures the reactions were steady and the following

results obtained (Table III).

- 6 -

TABLE III.

EFFECT OF SULFUR ON ASPHALTS AT 375-400°F (190-205° c)

California Kansas (S) Talco (S) Tia Juana (S)

Sulfur Concentration S.P. Time S.P. Time S.P. Time S.P. Time

% °F Min. °F Min. °F Min, °F Min.

2 149 810 123 680

3 180 1560 120 680 148 690

4 --- --- 142 1080 172 690

5 196 1200 147 660 196 690 162 660

6 168 1410 203 660

8 196 1 140 --- ---- 9 232 1 140

From extrapolations and interpolations of these results;, the concentrations

of sulfur required to approximate coating-grade softening points were determined and the following asphalts produced (Table IV).

3. RESULTS AND DISCUSSION

(a) Total Reflux

When asphalts are blown under conditions of relatively poor contact between

the blowing air and the asphalt flux, long periods of time are spent in the

stills. During this residence at high temperature the part of the air that

is not consumed tends to strip the more volatile components and reaction

products from the flux and discharge them with the exhaust gases. This

material is, quite frequently, burned along with the fuel to heat the

stills in commercial installations. As reported earlier (16), fluxes

with low molecular weight oils have the greatest losses; the California

flux blown without agitation lost as much as 11%. This loss of oils is

not only uneconomical, but it hardens the resulting asphalt unduly.

One way to reduce this type of blowing loss is to reflux the oils back

into the charge by means of a condenser on the exhaust port. When this was done on one of the laboratory blowing stills, the results reported

in Table V were obtained.

TABLE

IV

?0

4-J •H

t—l CJ CO 'H a-. Po <} <t 40 40

X> fl cd cn CM CO

CO r—

O

m 3Q

£-i o

4-1

m P o CO CM 40

CO T—

P 8 CM CM CM CM

T— "0

w 8 d pH O o P

°r4 n- § CO co co M r^ *— T— *

CO

P4 8 4J 8 04 0 p d CN| §

0) CO ”0 40 00 f'. 00

P*

g • 8 P4 U* LO 40 04 « o r—

1— r— 1—

CO CM CM CM CM do

•r-4 0)

®

O

O

O

O 4.) 6 P 40 f". O O °rl °H CO 40 00 40

c0

H s CM

co 0) H pi

r-1

B E 8 4-J CO 9 rH < 8 Cd 8 rP Q b a 4± r-'- 00

fr~] i co e • • o S 8 < 43 CO 40 4± Q \ p | l M9 X3

Pm r-4 3 Pm

3>

m

CO

O 40 CM I". 04

4J • • • • d m 04 00 d X)

4-1 0) r—83 'd

CO <X3

r-H 40 40 04

Ua • • • o m *

<o- CM PM

“"4

4-J 44 —4 O

4-* CO

44 4J * CO O 4-4 3 °r4 CO o cO d CO d

p4 4»/ co o cn 3

4-1 cO o |-o *H co o

rH

d r-4 cO

cd CO cO •r4 U P4 H H

TABLE V i r HO i-H |l *-***. D U id s co| B cd & i On id o 00 0 X E i r—1 X—1 CO b vO B o 

CM CO 3 $SI B cd g 0 a 0 S cd X 1 — 0 3 « 5 “D r-H 0 O VO G^ o CM 3 44 o rH r-H rH CM ON 1 GA I cd CU 0 CM Cl 3 “H P^ 0 i H B 0 0I i—I D g \ OB80 X B 3 I r—H H 4H j CU 5 H a) O N CM H N n CTi • LO! Cl rH I

n- <fn

m in o cm t—I

i—I CM Cl i—i « lO 1 cm o i P4 i 8 • EH j D <u

fl

B

d

B

B

d

B

D bO

w • «-4 0 D °H d d cd o CM 0 4-1 o •H -O g 8 CM r^ CM cm <r li •H s U M | rH H i—i

CO (=4 9 LOO CO

4-1 ! cd

O 1 CM CM

O 1 •H

"I

—1 d

W ;z;o

B rd

d o i B 4-1 d Eh ! B o o X B S d oon a 3 i GA LO 00 Cl CM CM 8 •H 4J i—i X 1 I t—1

rH CM

m * vO 0 X 4-1 cd 44 | CM m o 0 d d LO eh CU fi B <u rH & 0 0 d

44

B o d

cu

m 0 H

pd

C 3 0 O o 3 0 d

M •rH r-H o B •HI

cu 4-1 /—> cd

B GA i-4 CO o m LO 3 d cd 44 x—1 i—1 i—i

CO

O “ b CO

d 4-1 4H 1 CM lO CM i •H d •iH O O 1 i bO CO B CO bO <d B 8 CO d B 8 o

'H o o X i 0 t—1 £ o 3 i H B O X—1 i—i g r^ CO o LO o o LO 3 u i—l * cd 44 j rH r-4 CM CO <)• a vOtl Q) PP PH Eh CU 1 CM in >

1 B 44 O ftfl I 00 u LO fl £

•H 1 0 cd < g

fl

J4 j B 44 t— E 1 Cd B CO o\ r-* o o <t B cd CM rH o * <f" 0 T)

•H 54

D CM Cl

O 0 <U

g

O o t-H 1 £ u £50 8 o

4-1 •H

X s 0 I cd a 4-1 i a> i pd ii

4-1 d o O i-i ~m0 I CM1 i «* i—I | o rH i—i

cu CO LO ! P4 d

*\ £ CO o C\ r* pH •H o

bO *iH P4 Ph

O EH 44 | d 4-) O O LO •H g •r4 Cd CM r-» i—1

bO 00 i—l \ d d CO 1—1 d d •H B cu 4J •i4 •H .Q 1 4-4 CU 44 44 44 > cd i 4H d cd cd cd o o 54 1 O

CP 0) P4 X

—1 PQ

a 3 b po

Oi id o CO CO LO CO 0 4J rH rH CM LO *> LO S CU CM o B d 0 d B d

CO 0

Cd

B 4J

pH

g

Q 0 d

O

gg

B • eng

d

CU U

cd oid

•H<d

•Hsico

Eh coU

4-4 o

ind4-1 •H£o1—I

PQ

d

cud

cu

4-4 (U d

4-1 os

CM| Cd| t

The blowing losses were reduced for each flux, but most dramatically for

the California one, Here, a prohibitively high loss of 10 percent was reduced to 0.5%, even though the blowing time was increased 50%. While

the resultant asphalt was not improved sufficiently to meet coating-grade

requirements, its penetrations were increased and its durability improved.

The losses for both the soft and hard Talco fluxes were also reduced, and

the penetrations of the asphalt produced from the softer flux were increased.

However, the blowing time was shortened by 107o » This decrease in blowing

time may indicate that the oils returned to the asphalt were relatively

more susceptible to the changes that are produced by blowing than those

that normally remain in the residue (18). This speculation is given

further credence by the fact that the asphalt produced under reflux

conditions from the harder Talco flux required a longer blowing time than

did the soft flux under the same conditions. The material lost during

reduction from the soft flux (175/200 pen.) to the hard flux (85/100 pen.) were these same susceptible oils. Unfortunately, an arbitrary change in

the air rate to permit the completion of runs in one day left no "normal"

run for the hard Talco flux to be compared with the reflux run. The

durability of the Talco asphalt produced from the soft flux under reflux

was appreciably greater than that of the normally produced asphalt.

The Tia Juana asphalts produced under reflux were also appreciably more durable than their normally produced counterparts. However, little

change in the penetrations and only slight increases in the blowing

times were observed. The blowing losses were reduced to zero for the

soft flux; loss determinations were not made for the hard flux.

In summary, it is apparent that refluxing the oils always improved the

durability of the resultant coating-grade asphalts and usually improved

the softening point-penetration relationships. The blowing time was usually increased, but where reactive oils were refluxed, it was decreased.

The changes were most pronounced for asphalts that normally had appreciable blowing losses.

(b) Blowing Under Pressure

Because of the complexity of the reactions occurring during blowing, it

would be difficult to anticipate the precise effects of increased

pressure. There are a number of positive effects, such as increased

solubility of oxygen in the charge, reduction of volume by oxygen

combination with molecules in the asphalt and decreased bubble size,

which should tend to increase the reaction rate. There are neutral

effects, such as maintenance of the same proportions of nitrogen to

oxygen and the formation of one molecule of carbon dioxide from one molecule of oxygen. And there are negative effects, such as the

formation of two molecules of water from each molecule of oxygen, the increased solubility of volatile reaction products in the charge and the

smaller volume of unreacted gases sweeping the reaction products from

the charge. The net effect would be the resultant of these and other

unanticipated factors; the nature of the net effect should be related

to both processing conditions and asphalt source.

Examination of the data in Table VI reveals that the effect of pressure

on the processing and properties of the fluxes was quite variable. In one instance (soft Talco flux), the blowing time was reduced by 20%; in

another, the hard flux from the same Talco source, it was increased 30%

;

and in the two other instances for which comparable data are available,

the blowing time was unaffected. The penetrations of the asphalt produced from the California flux blown under pressure were increased

appreciably, but those of asphalts produced from the other fluxes were

changed only to a minor degree. The asphalts blown under 25 psig

pressure were all appreciably more durable than their counterparts

blown at atmospheric pressure. The improvements ranged from 10 to 17

days, averaging about 207>.

Chelton, Traxler and Romberg (2) had reported a decrease in blowing

time and an increase in penetration at 77°F for Texas and Louisiana

fluxes blown under pressure; the magnitudes of the effects were different for the two, however. This work shows that for some fluxes these

improvements are valid; for others, little effect on penetration or blowing time was observed at 25 psig.

(c) Blowing with Oxygen-Enriched Air

Whenever air is used in a controlled oxidation process, enrichment

with oxygen can be used to increase existing capacity at a relatively

low initial investment cost. The proportion of oxygen that can be used

is related to the economics and physical limitations of the process.

In the case of air blowing of asphalts, the use of oxygen alone has

been reported both at normal blowing temperatures (4) and at lower-thannormal blowing temperatures (6). The oxygen in both instances reduced

the blowing times, but in neither were sufficient data reported to describe the products sufficiently well to determine if oxygen changed

their properties appreciably.

The data in Table VII describe the asphalts produced with 257> oxygen

enrichment of the blowing air without changing its volume flow rate.

The entrance air was 40 percent oxygen. This enrichment shortened the

blowing times for all four fluxes by from 30 to 50 percent. Greater

enrichment would be expected to reduce it further. The exact acceleration

would depend on the efficiency of contact, time of contact, nature of the

flux and conditions of blowing. Graham, et al (4), working with a Lloydminster flux, found a 707> acceleration when 1007> oxygen was used.
I

•
I w

hJ

PQ£ ^ s 1 1 | TO CO 1 rH| d P i r^ ON \£> o d M 1 rH r—1

CO i td O I CM CO Si

CO f1 d OjOi cO •H | O

OmO VO CM

d CO 1 i—1

|—H

CM •

*"3 os CM CM o

Pd

4-J cd i CM Or vO •vf 08

4H P 3 rH rH CM CO o • OI o H E CM CM o CO O !

cd ! d t>0l cd °H | o <t o Ml- o 00 08 2 CO 1 pH pH CM CO pH ® r- j O OB CM CM o

CO 9 LO i •H CM 1 H 11 d 9 i—1 J •r-1

cd

g 8 a £ i On CM CM CM r^i

TO Ci ! 1 rH ,

i co pH

® LOI c d OI CM CM o

CD o cO d H 00 i 3 S '— i w CO &0i m 4J o •H 1 o O CM rH <1- 1

CD <4H o CO ! rH 1—1 1—1co 00 • i d O r—1

0,1 CM CM o

CL,

m cd 1 i-H H m i d CM 1 CD * 9 TO d 1 d o 1 S •l—l T 1 | 4J cd i ON CM Or MO r^ or Ol

bO cd /•s P i ,—1

rH r“H co rH • LOI

d 4-J 4-J

M 1 CM CO

O •1—1

•H <4H

O i £ ttf) O 13 1 o < CO 1 T 1 1 PQ O txOl o •H | CO o 00 00 00 Ol d o CO 9 i—i

i-H CM co LO • 08

•H * 1—1 08 CM CM o c PH cd 8 O H UO 1 ln CM 1 g i 00 00 O CO 9 d d ! t-H 1—1 • 1 •rl O ! CM CM o 8 d Si g d I I CD O I 8 4-> Cd 00! 1 d

•d •H | O CM 00 i—1 | Pd i—1 CO 8 rH t—1

CM OI

d 09 CM CM o 1 d u 8 1 •H w

!>J

cfl O o •H OI

O

u

O

O rH

a

•s-O tr^ OM Eh

d pH l-H '"''H. 1 1 \ •H "— — ,—1

*- #> \—1 1

CO o t-H pH CD CO LOI 4-J Pd d #\ e CO V-/| mh o " pL, •r4 o >4 UO

bO •H pH Pd o H 4-J 1 1^- d 4-J O o lO •H | •H d CM 1"- i—1

00 00 rH | d d CO r- i—i d d •H | CD 4J •H •H r^l i”1 | 4-1 CD 4-» 4-J 4-1 £ cdi Cd d cd d d O o JHI O CD 1 1 t—H

di

CO P-i PQ PQ (Hi

d

•Haid

TABLE VII

Blowing with 25% Oxygen-Enriched Air

475° F, No Agitation , 150ft 3 /Ton-Min

California Kansas (Soft) Talco ( Sof t

)

Tia Juana (Soft)

25%0 2 Normal 257o02 Normal 25%Q2 Normal 257o0 2 Normal

Softening Point, °F 217 217 217 221 219 219 217 217

Penetrat ions

at 32°F, 1/10 mm 7 4 14 11 13 12 14 14

at 77°F, 1/10 mm 11 8 20 19 18 19 21 22

at 115°F, 1/10 mm 23 18 36 29 33 36 37 39

Suscept ibi lity 1.45 1.75 1.10 0.95 1.11 1.26 1.10 1.14

Blowing Time, Min 169 240 160 330 178 317 129 206

Blowing Loss, %> 0.9 5 .0 0.2 0.0 1.1 0.9 0.6 0.4

Durability (5 l-9c) ,Days 71 44 108 65 66 56 80 60

- 9

-

The penetrations of the California and Kansas asphalts were higher than

normal, but the former were not high enough to meet coating-grade specifications . The penetrations of the Talco and Tia Juana asphalts were essentially unchanged. The durabilities of all of the asphalts produced

with the oxygen-enriched air were higher than their normally produced

counterparts. The improvements ranged from 18 percent for the Talco

asphalts to 66 percent for the Kansas asphalts.

Thus,, the use of oxygen to enrich the blowing air always decreased the

blowing time and increased the durabilities of asphalts from the four sources

.

(d) Blowing with Chlorine-Enriched Air - (Table VIII)

The use of 57c or 107o chlorine in the blowing air greatly accelerated the

hardening of all four fluxes. The accelerations were appreciably greater

than those produced by the oxygen-enrichment. As blowing progressed

,

copious quantities of hydrochloric acid gas were produced, indicating

that much of the chlorine was consumed in dehydrogenating the fluxes.

Analyses of the blown asphalts revealed that only 8-11 percent of the

chlorine used remained with the asphalts. These results are in agreement with Sanderson 8 s (10), even though he used chlorine alone at

temperatures at which addition was the principal reaction and he stopped

when hydrochloric acid evolution .began. These results would indicate

that the chlorine addition products formed are relatively stable and once they have formed, the reactions become entirely dehydrogenations.

Because the literature reported chlorinated asphalts to have higher

penetrations for a given softening point than normally blown asphalts,,

the hard fluxes were used for this series. In all instances, 1 0X

chlorine in the blowing air significantly increased the penetrations

of the blown asphalts; it even brought the California asphalt into

normal coating-grade specifications (16).

Whereas blown asphalts normally have flash points very close to those

of the fluxes from which they were produced, the California and Talco

asphalts produced with chlorine had flash points significantly higher

than their fluxes.

The chlorinated asphalts were all more durable than their corresponding

normally produced asphalts. While the increases in durability were not

great, they ranged from 14 percent for the Talco asphalts to 38 percent

for the Tia Juana asphalts.

IIII1II O l 531 1 1 CMi—i

CM

(J'v vO

O ’—I <j" i—i co cn i • co i—i

CO CM

O CO UO

i—I CM •<(- CM CO ! t—I II O 00 1 I I N v£)l <d 1IItII CTn U0 u0 I • ' 1 O'! I <t • \d I O l1 HM>W

id

PP<dH

S-J •rH C

03

C 0 t- rC -~ o co

5-1 0W0d

•j

—I

5-4 O

p-H -do

-du

•H&

00d

•rHo

r-H W

0CO

53

Ph ouO

rd

5-i O

<4-1

-r-4 i—I do

c?> t—<

CnI

Ol

N CM 00 OJ

t-H r-H CO r-4 r-4 * CM

<t" o 1—1

<f o o <n

h 00 oo

CM

H

N CO

H <f * CM 1—i o uO

ON ^ CO <D

O

N 00

rH I—1 CO U0 o * 1 CM « CM 1—1 o i—1

00 oo 00 CO UO CM CO

CM

h

n

M o cn « CM i—i o

o> CO <J- GO 00 CO CO v£> i—l i—1 CM CO O uo * « CM I—1 O CO

00 00 U0

O

O i—1

i—1 O- <f * 1 CM • CM

r-4 LO o o cm on <n vQ CM i—1 H H CO CO -f * • CM I—1 o

CO On UO On CO UO vd 1—1

CM i—1 CM CO O' * (# CM * O uo

O O'. vD UO U0 o o <n n o <o • ^ o

U0 I

1 CO 00

vd

CO

O o

uo no co OI UO ON

CM 00

cd I O <1- vd <

i-l

OO

cd 00 vd * <t o o I Go

(D 4Jd

Pi

!-< •rH1 < C/2 I 5oi Pm d i o Q i o 1 | c d3 /-\ /^l o •rH 0) C_) U 1

4-J o o 5 1 S d o 1 £ 5 1 1—1

kO *0 •rH o I 1 •H \ 1—1

4-J r> to 03

d '—T 1—1 0 o CO 1 1 rH1

•pH 0 w CL) 4-J 4-1 4-J uo l p , r—1 g c/2 02 i—l d i—1 4-J ^1 o r\ pH •rH •P o P d pi d d Pol 00 •H pH pH o H -d -d *r4 4-J 1 £ 4-1 0 0 uo •rl CU Cu 0 CL o •H | •rH ctf CM i—1

4-J 00 00

d 02

d 02 Ph »

1 1 £ J-l CO r^. rH o- d d •rH < •pH < ^

•rH |

(D 4_J CD •r4 •pH 54 5-4 -d r& 1

4_) 0) 4-J 4-J 4-J

O & O <4-4

O <4-4 CO CCJ 1

M-4 c ctf Ctf cti CO

O o r-H

O l 1 o d 5h i Q cu 2 rH rH -d -d rH 2 1 CO Ph in PP PQ a S'® u g-S P4 Q l d

•HsidoH

CO<4-4 U0

O'-

- 10 -

(f) Blowing Asphalts in the Presence of Sulfur - (Table IX)

As discussed by Martin (13), the effect of sulfur on the oxidation of

asphalts is not well understood. No work has been reported on the effect

of blowing with sulfur and air on the durability of asphalts. However,

Bencowitz and Boe (19) reported that asphalts hardened with 25% and 40%,

sulfur under conditions which did not involve the evolution of hydrogen

sulfide tended to increase more slowly in softening point and decrease

more rapidly in penetration during weathering than did normally produced

asphalts

.

Sulfur was very effective in decreasing the time required to blow each

flux to a coating-grade softening point. Five percent sulfur reduced

the time about 40% for three of the fluxes and 70%, for the California

flux. Ten percent sulfur reduced the time another 40%, for the Kansas

flux and another 27% for the California flux. The latter required only

eight minutes; the asphalt product in the latter case was so reactive

that it hardened too much on reheating to permit the determination of

meaningful penetrations.

Sulfur generally reduced the durabilities of the asphalts. At the five

percent level the reduction ranged from zero for the California asphalts

to 40 percent for the Talco asphalts. The reduction was much greater

when 10 percent sulfur was used, ranging to over 75 percent for the

California asphalt. Even though chemical analyses showed that only

small permanent increases in the concentration of sulfur occurred, all

of the asphalts blown with sulfur continued to change faster than

normal when heated to the vicinity of 40Q°F (200°C),

Because of the violence of the reaction between sulfur and asphalt flux

in the absence of blowing air above about 425°F (218°C), the reactions

were conducted between 375 and 400°F (190“2Q5°C). Only sufficient

sulfur was used to permit the reaction to be essentially complete at

softening points near those of coating-grade asphalts. As seen in

Table IV, the reaction times were extremely long at these temperatures

and only 20 to 25 percent of the sulfur used remained in the asphalts.

Very little additional hardening occurred during the preparation of

exposure specimens. The penetrations were drastically lowered for all

except the asphalt produced from the California flux, which were

similar to those of the normally produced asphalt.

Blowing

Asphalts

in

Presence

of

Sulfur

CD

r fi M

CN ON 40 ON 08

rH rH .CN CO

O * <* NO i C\S CM o CN 110J

tH o r-. *H s8 IT) 0 CN rH rH CN CM © « <t* 8 CN ^—1 o CO B

ON CM ON NO ON NO NO

C rH r-4 rH CO rH <•> m s CN CO o B

fi8

ON r-* o 38 <t o rH rH CN 00 0 1 CO 0

cO s

CO !1 B-2 1

LTi f

CM

CM

co

CM

CM

r-- r—I

CN

rH

CN

CO H s e E M cn j O J oo

4-1 S-5l CM H O t CM i—i

>—1 1 c0 1 a 0 fH

CNJ

Phu£

•HO

PhbO£

fia) •M CMO

CO

tH ON ON o o LO 0 rH H CN co NO § co o H !e8 eo 0 C 8 o

00 iO

N o CN CN i M rH CN M> * ( CO 3 U

rH

D CO 8 fi 0 •rl 3 e

CN GQ CN ON 00 CO i u

rH i—1 CO 00 <* 1 LO 3 Qj \—1 o 8 U 1 a; B xi I1 fi 1 o 8 °M 8 4-1 <<r oo co o o NO <tB CO rH * * 8 M

CM LO

m 8 iJ A 0) A fi 1 CD 8 Cl. rH J rH| rH [ 00 D O o M B 8 '—1 D O 0 44 I8 tot) 8 fi NO H CO M3 00 NO D •i—i '—1 CN M3 ® <± 3 4-1 o NO 11 CO

(| cu 1 -fi 0 cu t M

CO 0 >NB fi

Ctf l O

4-J Qi CL £ rH 8 fi 6 E! h I g C -nG X o °rl Cl a b CU O O i-i & co ON 8 fi rH i—1 "s^. C 8 e CU ~ ~~ rH c\ «* i

i a X tH xH cu co M-l m 8 M * e CO O "

y \ fi e\ «\ pL| °i—t o koo td

pH Ph

O

H 4-1

D

OO LO •H 0 CN 8 :—1

00 00 i—1 fi co i—i •H

fi ®H£ u •H 0 H £ XU

4J 4-) 4J £ M-l cd i

ctf cd £ o o i—l

Ui

rH rH 2 £«

pp PQ cn Qc

11 -

The durabilities of the normally produced asphalts generally varied inversely with the sulfur content of the fluxes from which they were produced (but were not necessarily related to sulfur content) ; there was no trend of durability with sulfur content of asphalts hardened with sulfur.

The durabilities of all but the California asphalt were greatly reduced;

that of the California asphalt was unchanged. From these data it would seem that sulfur can, at best, produce asphalts similar to those produced

by air blowing and usually produces asphalts markedly inferior for roofing

uses.

4, BIBLIOGRAPHY

(1) Murayama, K, ; T. Fukushima, Y„ Fukuda, and A. Shimada, Bull.. Jap.

Pet. Inst. _2, 63-9 (1960).

(2) Ghelton, A. M, , K. N. Traxler, and J. W. Romberg, Ind. Eng., Ghem.

5JL, 1353-4 (1959).

(3) Levinter, M. K. and M. F t. Galiakbarov, Khim. i Teknol. Topliv, i

Mas el 9, 32-6 (1964).

(4) Graham, W. , W, J. G. Cudmore, and R. D. Heyding, Can. J. Technol. 30 3 143-52 (1952).

(5) Shearon, W. H. , Jr. and A. J. Hoiberg, Ind. Eng, Ghent. 45, 2122-32

(1953) .

(6) Campbell, P. G. and J. R. Wright, Ind. Eng. Chem, Prod. Res. and

Dev. 3, 186-194 (1964).

(7) Abraham, H. , Asphalt and Allied Substances, 0. Van Nostrand, Sixth

Ed., II, 169 (1964).

(8) Pfeiffer, J. P., The Properties of Asphaltic Bitumen, Elsevier

Publishing Go,, 1950.

(9) Pauer, V. 0. and M. M. Earuni, Erdol u Kohle 1

2

, 771=773 (1952).

(10) Sanderson, F. C., Highway Res. Bd. Bull. 118, 1=11 (1956)

(11) (a) Douthett, 0. R., U.S.P. 1,979,677, Nov. 6, 1934.

(b) Sparks, J. W., U.S.P. 2,059,051, Oct. 27, 1936.

(c) McConnell, E. B., U.S.P. 2,148,869, Feb. 28, 1939.

12

( 12 )

(13)

( 14)

05)

(16)

(17)

(18)

(d) Burk, R* E. and C s H s Whitacre, U.S.P. 2,200,914, May 14, 1940.

(e) Mauch, K» and 0, Pauer, U.SoP,, 2,348,832, May 16, 1944 0

Abraham, EL, Asphalt and Allied Substances, D. Van Nostrand, Sixth

Ed., n, 156, 178-179 (1964).

Martin, K* G„, J. Inst. Pet. 47, 321-328 (1961).

Sulfur in Bitumens - A Literature Survey, The Sulfur Institute Tech.

Bull. 7, (1963).

Tucker, J e R„ and H. E.. Schweyer, lnd„ Eng. Cfaem, Prod. Res. and Dev.

4, 51-57 (1965)

.

G'reenfeld, S. H. Xnd„ Eng. Chem. Prod. Res. and Dev. 3_, 158-164

(1964).

Greenfeld, S« H., NBS Report 8607, Air Blowing Asphalts in the

Presence of Additive Oils, Catalysts and Polymers, Dec. 15, 1964.

Greenfeld, S.. H, and J e C, Weeks, NBS Report 8110, A Comparison

of Thin-Film Oxidation with Conventional Weafcherometer Exposures,

Oct. 18, 1963.

(19) Bencowitz, I. and E, S. Boe, Effect of Sulfur on Some of the

Properties of Asphalts, ASTM Preprint, 9 pp. (1938).

5 . ACKNOWLEDGMENT

This work was sponsored by the Asphalt Roofing Industry Bureau at the

National Bureau of Standards under the guidance of their Research

Committee. The author gratefully acknowledges the advice of the

members of the Research Committee, both individually and collectively,

and the help of Messrs. T. R„ Davis and J 0 C. Weeks, AE.IB Research

Associates, for their assistance in collecting the data reported here.

i}