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April 1955

I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y

85

temperature, the solubility was determined by contacting a

known volume of gas with a known volume of liquid. Th e es-

sential parts of the a pparatus are a gas buret for determining th e

volume

of

acetylene before and after absorption and a n absorption

flask for contacting th e acetylene with t he solvent.

In operation, t he entire system from the gas buret to the ab-

sorption flask is first swept free of air with acetylene. After the

system has been purged, th e pressure of the acetylene remaining

is brought to atmospheric pressure by adjusting the mercury

level in the gas buret. A reading of the gas buret is taken, and

a

known amount of solvent is introduced through

a

specially

designed funnel on the absorption flask. Th e solvent is then

cooled in an ice bath a nd stirred with a magnetic stirrer until no

more acetylene dissolves. Th e ice ba th is removed and allowed

to warm to room temperature, under constant stirring, until

equilibrium is established.

A

new reading on the gas buret is

take n with t he acetylene a t atmospheric pressure.

Table I11 shows the “normalized” experimental solubility of

acetylene in a number of solvents compared to the calculated

solubility.

,

LITERATURE CITED

(1) E. I. du Pont de Nemours

&

Co., Wilmington 98, Del., Grasse

(2)

Gilman, H. , “Organic Chemistry,” pp. 1844, 1847, Wiley, Ne

Chemicals Dept.,

product

information bull. (Feb. 2, 1951).

York. 1943.

(3) Hildebrand, J. E., “Solubility

of

Non-Electrolytes,” 2nd ed., p

(4) Huemer, H. , Library

of

Congress, Washington 25, D. C., Micro

(5) Levine, M., and Isham, R. AI . , U.

S.

Patent 2,623,611, 1953.

(6) Xieuwland, J . A., and Vogt, R. R., “Chemistry of Acetylene

(7) Ibid. pp. 154, 182.

(8) Pauling,

L.,

“Nature

of

the Chemical

Bond,” p. 64,

Corne

(9)

I b id . , pp.

154,

182.

104, Reinhold, New York, 1936.

film Reel PB 73508,

p.

7274, 1942.

p.

30, Reinhold, New

York,

1945.

University Press, Ithaca , N.

Y.,

1939.

(10)

Zellhoefer, G. F., and Copley,RI. J., J . Am Chem Soc., 60,

134

RECEIVEDor review Jun e 7, 1964. ACCEPTED ovember

12,

195

Division of Petroleum Chemistry, 125th Meeting, ACS, Kansas City, M o

1954.

(1938).

Plasticization of Polyvinyl

Chloride

with

Alky l

Esters

of Pinic

Acid

R .

F. CONYNE

AND

E.

A . Y E H L E

Rohm Haas Co., Philadelphia 37 Pa.

PlNlC

ACID

ESTERS

. . ave interesting plasticizing prop

.

.

.

may be useful secondary plasti

cizers

i f

they become commer

cially available

at

moderate cost

erties

HE large and growing usage

of

the esters of phthalic,

T

dipic, azelaic, and sebacic acids as plasticizers for poly-

vinyl chloride leads to an understandable interest in t he adapt-

ability of othe r dibasic acids as raw materials for the preparation

of simila r esters.

Such a raw material is pinic acid, prepared by th e oxidation of

a-pinene 3 )

cy

w

CH3 CH3

2 Steps

EVALUATION

METHODS

These esters were evaluated as plasticizers for polyviny

chloride in t he following formulation:

Polyvinyl chloride (Geon

101a)

60.0

Plasticizer 40.0

.

Tribasic lead sulfate (Tribaseb) 1. 0

Stearic acid 0 . 5

a

B. F.

Goodrich Chemical Co.

b

Xational Lead

Co.

The dry ingredients were blended;

the plasticizer was adde

to the dr y blend; and th e whole was thoroughly blended a

room temperature and charged immediately to a

6

X

12 inc

rubber mill operating

at a

rpll surface temperature of 325” F

The batch was mixed for 5 minutes after reaching the state

o

qualitative homogeneity which indicates that plasticizer an

resin ar e “fluxed.” At this point, th e batch was removed fro

the rolls in three portions:

Sheet, 0.100-inch th ick , subsequentl y molded (20 minute

at 323’ F.) t o yield 6 X 6

X

0.072 inch test panels

Sheet, 0.070 inch thick , for hea t stability tes ts

Film, 0.010 inch thick, fo r permanence testing

1.

2.

3.

Modulus in tension ( l o o ) , Shore A hardness, and low-tem

perature flexibility measurements were made on the 0,072-inc

molded panels. Th e lorn temperature flexibility tests used in

cluded determi nation of torsional modulus as a function

of

tem

perature (ASTM D-1043-49T) 1) nd determination of britt

point by

a

modification

of

ASTM D746-44T

2 ) .

Th e modifica

tion consisted of using tes t specimens that had been conditione

for 24 hours a t 5” C. immediately prior to testing.

Hea t stability was measured as the number o

/ \

\g/

0 CH,

~ 0 - c - c ~ CH-CH~-C-OH

hours

of

exposure a t 350” F. necessary to caus

the first abrupt discoloration of test samples cu

from the 70-mil te st shee t. Samp les of IO-mil film

were exposed in a Fade-0-Meter. The minimum

number of hours exposure required t o cause th e sample to crac

when folded sharply on itself was tak en as an index of ligh t sta

bility of t he film.

I1

 

H&

ck,

I

\ /

The alkyl esters

of

pinic acid listed in Tab le

I

were prepared and

characterized by th e Kava1 Stores Research Division of th e

U

S.

Depa rtme nt of Agriculture, Olustee, Fla.

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a54

I N D U S T R I A L A N D E N G I N E E R I N G

C H E M I S T R Y

Vol. 47 No. 4

In determining volatility,

a

tightly capped 16-ounce wide-

mout hed jar /containing a )

a

120-cc. layer of e/Ih-mesh Columbia

activated carbon, Grade AC; b ) a weighed 2

X 2 X

0.010 inch

specimen;

c )

a second 120-cc. layer of carbon;

d )

another test

specimen from the same film; and e ) a thi rd 120-cc. layer of t he

activated carbon was placed in an oven operating

at

90 C. for

24

hours. At th e end of th is time the jar was cooled in air for

15

minutes a t 25

C.,

the specimens were removed and brushed

free of carbon particles, an d th e loss in weight observed on re-

weighing was recorded as the volatility .

Table 1. Properties

of

Esters

Boiling Point

olecular

Weight

(Theory) n? C. M m . H g

_ .

Di-n-decyl pinate

In determining extraction losses, 3 X

3 X

0.010 inch samples

of film were immersed a ) in tap water for

10

days

at

room tem-

perature; b ) in refined mineral oil (Atreol

No. 9,

Atlantic

Refining

Co.)

for

10

days

at

room temperature; c ) in 1 solu-

tion of Ivor y soap in ta p wate r for 24 hours

at

60

C.; and

d )

in nonleaded gasoline for

1

hour at 25

C .

After immersion,

the test samples used in the soap solution and gasoline extrac-

tion tests were heated for 45 minutes a t 85' C. in

a

specially

designed volatility oven 4 ) . All samples were conditioned for

16

to

24

hours

at

25 C. and 50% relative humid ity before re-

weighing,

Compatibility comparisons were based on qualitative observa-

tion s of 0.072-inch molded panels a nd 0.010-inch film after various

periods of natu ral aging. Th e development of exudation during

accelerated light exposure was also observed. These observations

were supplemented b y quanti tative measurements of the amount

of plasticizer exuding from 4 X 4 X

0.010

inch film when placed

between two sheet s of showcard stock (Concoratex, Container

Corp. of America) and subject ed to a pressure

of

0.4 pound per

square inch for 7 days a t room temperature.

811 volatili ty, extraction, and compatibili ty values (Tabl e 11)

are th e averages of duplicate determinations.

DISCUSSION OF RESULTS

As plasticizers for polyvinyl chloride, the pinic acid esters

discussed here show average plasticizing efficiency, adequat e

heat- and light-stability properties, and permanence properties

which are character ist ic of monomer ic plasticizers of simil ar

molecular weights.

Low

temperature flexibility properties are

good to excellent, but compatibility properties are rather poor

(Table 11 . Since good low tem per atu re flexibility and marginal

compatibility, respectively, appear

to

be the major advantage and

th e major limitat ion of th e pinates as plasticizers, these proper-

ties meri t more detailed consideration.

Compatibility is th e critical property th at must be considered

in evaluating the performance

of

these esters versus that of com-

mercially accepted standards. A high degree of compatibil ity,

as indicated b y freedom from exudation, is of obvious importance

per Be. It is of equally great, albeit less obvious, importance in

th e interpretat ion of t he influence of these esters on mechanical

and permanence property values.

The differential between brittle point values and

TI

alues

(torsional modulus of 135,000 pounds per square inch) tends to

increase with decreasing compatibi lity between the polyvinyl

chloride and th e plasticizing ester (Tab le 111). Thi s trend is

believed t o result from the fact t ha t th e brittle-point t est is pri-

marily

a

measure of '%oughness7'a t low temperatures while the

torsional-modulus te st is a measure of softness. Th us with

polyvinyl chloride, t he less compatible e sters of pinic acid yield

two-phase or incipient two-phase compositions

at

low tempera-

tures, and, quite understandably, these compositions show rela-

tively poorer resistance to low temperatur e fracture

at

high rates

of loading (brittle point) tha n t o deformation a t low rates of

loading Tp).

Whether the low temperature flex contribution

of

the higher

alkyl pinates is better indicated by bri ttle point

or

by Tf s a moot

question since these pinates would appear to be disqualified for

use as sole plasticizers by their poor compatibility. Of greater

practical significance is the low temperature flex contribution of

pinic acid esters such as the octyldecyl pinate when used as sec-

onda ry plasticizers in more compatible compositions. Her e th e

low temperature performance

of

octyldecyl pinate

is

better

predicted by the

T ,

value contributed by th e pinate when used as

the

sole

plasticizer than by t he corresponding brittl e point.

Similar considerations indicate t he supe riority of modulus at

100% elongation over Shore A hardness as a n index of the plasti-

cizing efficiency of t he plasticizer (Table IV).

Mechanical properties

100 Modulus, lb./ sq. inch

Shore

A

hardness

Brittle point, C.

Torsional modulus

Tf),

C.

Table 11.

Properties

of

Alkyl Pinate Plasticized Polyvinyl Chloride

Alkyl Pinate with

Dioctyl Phthalateb

Alkyl Pinate as Sole Plasticizera (1: 1 Pinate-DOP) Controls

Di-n- Di-(butoxy- Di-n- Di(2-ethyl-

Octyl-

Octyl- Di-n-

Dioctylb DioctylC

hexyl ethy l) octyl hexyl)

decyl decyl decyl phthalate sebacat e

1110

1190

1300 1300

1310 1220 1280 1190 1020

65

66

72 70 78 69

70 68 66

- 4

- 7 -48 - 0 6

2 -43

-31

-

2

- 5 0 . 5 - 4 6 . 0 - 5 8 . 0 - 4 6 . 5 5 - 4 7 . 5 - 4 6 . 5 - 3 3 . 5 - 6 8 . 5

Permanence properties

Volatility

loss

2 0 . 4 1 2 . 1

4 . 7 7 . 4

6 . 1 4 . 5 4 . 3 8 . 4 4 . 1

Wat er ext'raction loss

0 . 4 2 . 3 0 . 5

0.1

0 . 3 0 . 0 4

0 . 0 5

0 . 0 2

0 . 0 4

Oil extraction

'

loss

2 3 . 7 2 0 . 7 1 4 . 7

16.9 10.1

2 0 . 5 1 8 . 1 1 3 . 2 1 7 . 5

soapy water Lxtraction

loss

1 4 . 2 2 3 . 4 3 . 4 1.9

2 . 3 0 . 7

0 . 7

2 . 0 + 0 . 4

Gasoline extracti on, loss 2 7 . 2 2 6 . 4 3 0 . 7 3 0 . 2

3 2 . 8 3 0 . 1

30

9

2 6 . 1 3 2 . 0

Stabili ty properties

Heat stability, hr. at

350

F.

Light stability, Fade-0-Meter hr.

3-4 1 x 4 3

3

252 252 323 2 52

Compatibility properties

Exudation after 1 day/rm . temp. Slight

Slight

Definite Slight Definite None Slight None Slight

Exudation after

1

month/r m. temp. Slight to Bad Bad Definite Bad Slight to Definite Kone Definite

Exudation after

41

Fade-0 -Meter hr. Slight

Definite

Definite

Slight Definite

Slight Slight None Slight

Quantit ative exudation test, loss 1 . 6 1.9

3 . 4 2 . 2

4 . 3 0.9

1 . 4 0 . 1 3 . 1

definite definite

Di-n-decyl pinate incompatible on mill.

b Flexol DOP, Carbide and Carbon Chemical Co.

C Monoplex DOS, Rohm

&

Haas

Co.

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April 1955 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y

Table 111.

Low Temperature Flexibility and Plasticizing

Efficiency Related

to

Compatibility

(Alkyl pinate esters)

Octyl- Di-n - Di(2-et hyl- Di-butox y- Di-n-

dedyl

octyl hexyl) ethyl hexyl

Britile point, ‘C. -46 -48 -40 -47 -54

C . -65

-58 -46 .5 -46 -50 .5

;

brittle point - 9 - 0 - 0 . 5

+ I

f 3 . 5

Quantitative exuda-

tion test, ’X loss 4 . 3 3 . 4 2 . 2 1 . 9 1 . 6

Shore A hardness 78 72 70 66 65

Modulus

(lOO~o),

lb./sq. inch 1310 1300 1300

1190

1110

Table IV. Predicted versus Observed Behavior in Poly-

vinyl Chloride of 1: Octyldecyl Pinate-Dioctyl Phthalate

Octyldecyl Calcd. 1 :

1

Octyldecyl

Pinate DOP Mean Pinate-DOP

Britile point,

’

. 6 -31 -38 .5 -42

-

5 - 3 3 . 5 - 4 9 . 3 - 4 7 . 5

gkore? hardness 78 68 73 69

Modulus

( l o o ) ,

lb./sq. inch

1310 1190 1250 1220

Gross

differences in plasticizer permanence properties are in

accord with expectations-Le., a ) increased volatility with

decreasing molecular weight and with branching in the alkyl

group;

6)

increased water and soapy water sensitivity with

decreasing molecular weight and with the presence

of

an ether

linkage in t he alkyl group;

c)

increased gasoline extraction with

increaeing length of the alkyl group and decreased gasoline ex-

traction as a result of the presence

of

an et her linkage in the alkyl

group.

The observed apparent decrease in oil extraction with increas-

ing chain length of the alkyl group is probably caused by a ) a

tendency toward higher oil absorption by the films plasticiz

with th e higher alkyl pinates and 6 ) compensation for the pr

able inherently greater oil sensitivity

of

th e higher alkyl pina

by their lower rate s of diffusion.

Minor deviations from t he predic table order of influence of t

series

of

pinates on permanence properties can be interpreted

terms

of

th e extent of deviation from complete compatibil

Thus, t he abnormally high volatility an d soapy water extract

losses of th e octyldecyl pina te plasticized films are undoubte

composites of loss to t he indica ted haza rd plus loss throug h e

dation. This likelihood is borne out by the fact th at both

volatility and soapy water extraction values shown by

octyldecyl pinate-dioctyl phth alat e are much lower than

corresponding values

for

each of these two esters when pres

as th e sole plasticizer.

CONCLUSION

The permanence, stability, and low tempe rature propertie

th e n-octyl, octyldecyl, and 2-ethylhexyl diesters of pinic a

make these esters useful secondary plasticizers for polyvi

chloride. Pinic acid diesters derived from lower alcohols

excessively volati le while th e di-n-decyl ester is for most appl

tions inadequately compatible as

a

secondary plasticizer.

LITERATURE

CITED

(1) A.S.T.M.

Standards,

1949,

Part 6, p. 546.

(2)

Ibid.

p. 574

(3) Murphy, C. hl., O’Rear,

J.

G.,

and Zisman, W. A , , IND.

(4)Rider,

D.

K., and Sumner,

J.

K.,

IND. NG. HEiw., AN.~L

C H E M . ,5,

119 (1953).

17 730

(1945).

RECEIVEDor review August 20, 1954.

ACCEPTEDovernber

19, 1

Terpene-Derived Plasticizers

PREPARATI ON

O F

P I N I C A C ID A N D I T S E S T E R S

VIRGINIA ‘I.OEBLICH

Naval Stores Research St ati on, Ol ustee , Flu.

FRANK C. MAGNE

AND

ROBERT R M O D

South ern Regional Research Laboratory, New Orleans, La.

P’ THE

past few years the re has been increasing demand

for a

omestic supp ly of dibasic acids, such as sebacic acid, tha t

could be used in the preparation of synthetic lubricant s, low

tem pera tur e plasticizers, polymers, resins, an d fibers.

a-Pinene, t he main constituent of turpentine, will, by stepwise

oxidation, yield a series

of

dibasic acids; three

of

these are struc-

turall y identified as shown in Figure

1.

The st ructura l similarity

of these acids t o th e more common dicarboxylic acids suggests

the ir potentia l application in th e synthesis of plasticizers and low

temperature lubricants.

While the presence

of

cyclic groups, such as phenyl

or

cyclo-

hexyl, in diesters is generally considered unfavorable to the ir per-

formance as satisfactory low temperature lubricants by virtue

of th e large tempe ra ture coefficients of viscosity, high freezing

temperature,

or

pour points imparted, Murphy, O’Rear, and Zis-

man 6 )have shown th at the presence

of

the cyclobutane ring in

the pink acid

(I)

diesters does not cause such adverse effects.

Therefore, t he es ters of pinic acid should be potential ly good low

tem pera tur e plasticizers and those of sym-homopinic acid 11)

should be be tter ones because of th e more centered position

of

the

cyclobutane ring. Although severa l isomers of each acid (I

are indicated from st ruct ura l considerations, this stud y co

only esters of w hat is reported as th e d-trans isomer of pinic

and symhomo pinic acids 2,9) .

The octyl

P-(hydroxyisopropy1)pimelate

y-lactone 111) S),

th e other hand, with its oxygen-containing ring was hoped to h

an enhanced compatibility as well as the middle-range low t

pera tur e characteristics of an alkyl ester somewhere betwee

phthalate and a n adipate.

VINYL PLASTICIZERS

b sed

o n

d o m e s t i t u r p e n t i n e

co ns t i t uen ts

. . .are promising plasticizers for pol y

vinyl chloride and

PVC PVA

co

polymers

. . n some cases rival sebacic acid

esters in physical properties and

perf orma nce