in raw materials. T h e relationship of 2 to concentration is useful in comparing the viscosity behavior of different cellulose a c e t a t e s in concentrated solutions. It may a l s o point t o the manufacturing variables which affect t h e viscosity properties of the product. CONCL US IONS
N
a2
1
I
I
I
I
I
I
I
LITERATURE CITED
01
oh
T h e 2 power of t h e concentrated solution viscosities of secondary cellulose a c e t a t e in acetone w a s found t o b e approximately a linear function of intrinsic viscosity and concentration. A coefficient w a s introduced into t h e Baker-Philippoff equation t o give a n equation which would approximate the experimental data. T h i s coefficient varies with both intrinsic viscosity and concentration.
3
I 10
1 I5
I
I
I
20
25
30
I
WEIGHT PER CENT OF ESTER IN SOLUTION
Figure 7. Relationship of 2 with concentration for samples of cellulose acetate of different intrinsic v i s c o s i t i e s Using solvent of acetone containing 2.5% of water
There a r e factors which affect concentrated solution viscosities without affecting intrinsic viscosities. T h e y would, of course, a l s o affect 2. Some of t h e s e factors a r e methods of acetylation, s a l t s i n t h e product, or differences
(1) Am. Soc Testing Materials, Philadelphia, Pa., “ASTM Standards,” D 1343-54T, Tentative Method of T e s t for Viscosity of Cellulose Derivatives by Ball-Drop Method. (2) Baker, F., J . Chem. SOC. 103, 1653 (1913). ‘ ( 3 ) Browning, B. L . , Sell, L. O . , Joint TAPPI-ACS-ASTM, Disperse Viscosity Subcommittee, Project 1592, Progress Rept. 3, J a n 13, 1956 (not published). (4) Kauppi, T. A., B a s s , S. L., Znd. Eng. Chem. 29, 800 (1937). (5) Malm, C. J . , Tanghe, L. J . , Laird, B. C., Ibid., 38, 77 (1946). (6) Markwood, W. H., Jr., Am. SOC. Testing Materials, Proc. 51, 441 (1951). (7) Ott, Emil, Spurlin, H. M., eds., “Cellulose and Cellulose Derivatives,” High Polymers, vol. V, pp. 1212-22, Intclc science, New York, London, 1955. (8) Philippoff, W., H e s s , K., Z. physik. Chem. 831, 237 (1936). (9) Wagner, R. H . , others, Anal. Chem. 20, 151 (1948). Received for review September 13, 1956. Accepted April 25, 1957. Division of Cellulose Chemistry, 130th Meeting, ACS, Atlantic City, N. J., September 1956.
Viscosities of Solutions of Pine W o o d Lignin from Kraft Black Liquor LOUIS R. LAWSON, Jr., ond J. BAYNE DOUGHTY Research Laboratory, West Virginia Pulp and Paper Co., Charleston, S.
T h e lignin studied w a s a commercial pine wood lignin (Indulin A, Polychemicals Division, West Virginia Pulp and Paper Co.), recovered by acidification of kraft black liquor from the pulping of pine woods of the Southeast. A typical analysis a s offered by t h e manufacturer i s : moisture 4.3%, a s h 0.4%, methoxyl 13.9%, and sulfur 1.4%. Four fractions of the lignin prepared by fractionation with acetone and with methanol, and a chemically modified form were a l s o studied. T h e commercial lignin w a s fractionated according t o the procedure outlined in Figure 1. An oxidized lignin w a s prepared by passing oxygen g a s through an aqueous alkaline solution of the commercial lignin. A solution containing 20% of the commercial lignin w a s prepared in which 4 moles of alkali were used to each 840 grams of t h e lignin. T h e solution w a s heated to 7OoC. and oxygen g a s w a s passed in for 11.5 hours at a rate of 0.04 cu. foot per minute per 1000 grams of lignin. When oxygen addition had been completed, the mixture w a s heated to 90’C. and 1 2 1 sulfuric acid w a s added with good stirring until a pH of 2.0 w a s obtained. T h e acidified mixture w a s allowed to cool to 70°C. and then filtered. T h e oxidized lignin cake w a s washed with water until the wash water had a pH of 4.5. T h e lignin w a s then dried to constant weight at 105OC.
128
INDUSTRIAL AND ENGINEERING CHEMISTRY
C.
PREPARATION OF PYRIDINE SOLUTIONS FOR VISCOSITY TESTS
After being dried to constant weight, the lignin and lignin fractions were stored in ground-glass weighing bottles, which were kept in desiccators containing both concentrated sulfuric acid and sodium hydroxide p e l l e t s as desiccants. T h e pyridine used to make the t e s t solutions w a s Baker’s analyzed reagent grade 0 . T. Baker Chemical Co., Phillipsburg, N. 3.1. TESTS OF VISCOSITY OF LIGNIN-PYRIDINE SOLUTIONS
T h e viscometers used in the tests were the CannonFenske-Ostwald T y p e 50 (Cannon Instrument Co., S t a t e College, Pa.), standardized by the instrument company under t h e direction of M. R. Cannon. They held a charge of approximately 7.0 ml. and had a driving head of approximately 9.0 c m . , and t h e working diameter of t h e lower reservoir w a s 3.0 c m . Their suggested range of operation w a s 0.8 to 3 centistokes. T h e v i s c o s i t i e s of t h e pyridine solutions were determined at 20.00’ f 0.01’C. by the testing procedure recommended by t h e Cannon Instrument Co. T h e kinematic viscosity in centistokes for t h e pyridine solvent and the lignin solutions w a s obtained by multiplying the efflux t i m e i n s e c o n d s by the calibrated viscometer V O L . 3, NO. 1
ACETONE
PYRIDINE
PYRIDINE
PYRl D l NE
100% SOLUBLE
METHANOL
PYRl DI NE
PYRIDINE
1 0 0 %SOLUBLE
37% SOLUBLE
Figure
Table 1. Lignin Material in Solution
Lignin Concn., G/IOO G Soh.
Specific Gravity
None
i
1
63% INSOLUBLE
56% SOLUBLE
1. Solvent fractions o f p i n e
4 4 % INSOLUBLE
wood l i g n i n
V i s c o s i t y o f P i n e Wood L i g n i n Solutions
of Soh.
Flow Time of Liquid in Viscometer, Sec.
Centistokes
Centipoises
None
0.9836
505
0.975
0.969
...
0.31 0.45 0.81 1.07 1.43 1.96 2.58
0.9852 0.9853 0.9867 0.9875 0.9888 0.9899 0.9915
524 528 547 558 612 653
1.011 1.019 1.056 1.077 1.119 1.181 1.260
0.996 1.004 1.042 1.064 1.106 1.171 1.249
Methanolsoluble fraction
0.36 0.57 0.98 1.36 1.77 2.35
0.9854 0.9857 0.9868 0.9878 0.9888 0.9902
523 525 539 545 560 578
1.009 1.013 1.040 1.052 1.081 1.116
Methanolinsoluble pyridine soluble
0.22 0.37 0.59 0.75 1.03
0.9848 0.9850 0.9862 0.9861 0.9867
519 526 530 540 552
Acetonesoluble fraction
0.34 0.55 0.97 1.18 1.60 2.22
0.9819 0.9855 0.9867 0.9876 0.9883 0.9896
Acetoneinsoluble pyridinesoluble
0.12 0.22 0.71 1.06 1.40
0.9846 0.9859
Oxidized
0.54 0.88 1.04 1.53
Pine wood lignin
'Concentration,
g.
/loo
In N r Relative
C*
Specific
...
...
1.038 1.046 1.083 1.105 1.149 1.212 1.293
0.038 0.046 0.083 0.105 0.149 0.212 0.293
0.127 0.108 0.095 0.098 0.098 0.097 0.099
0.994 0.999 1.027 1.039 1.069 1.105
1.036 1.040 1.067 1.079 1.109 1.145
0.036 0.040 0.067 0.079 0.109 0.145
0.109 0.069 0.069 0.057 0.059 0.060
1.002 1.015 1.023 1.042 1.065
0.987 1.000 1.009 1.028 1.051
1.028 1.042 1.050 1.069 1.093
0.028 0.042 0,050 0.069 0.093
0.134 0.106 0.083 0.090 0.084
518 524 538 550 563 584
1.000 1.011 1.038 1.062 1.087 1.127
0.985 0.996 1.024 1.049 1.074 1.115
1.026 1.038 1.065 1.089 1.115 1.156
0.026 0.038 0.065 0.089 0,115 0.156
0.087 0.071 0.070 0.073 0.071 0.070
1.000 1.011 1.050 1.077 1.108
0.985 0.997
0.9874 0.9881
518 524 544 558 574
1.063 1.095
1.026 1.038 1.077 1.105 1.137
0.026 0.038 0.077 0.105 0.137
0.247 0.178 0.109 0.099 0.094
0.9867 0.9874 0.9888 0.9903
554 577 617 679
1.069 1.114 1.191 1.310
1.055 1.100 1.178 1.279
1.086 1.131 1.210 1.330
0.086 0.131 0.210 0.330
0.160 0.139 0.185 0.187
...
s ao
...
g, solution
constant. T h e v i s c o s i t y in c e n t i p o i s e s w a s obtained by multiplying t h e c e n t i s t o k e v a l u e s by t h e d e n s i t y of t h e solutions. T h e d e n s i t i e s of t h e solvent and s o l u t i o n s a t 20.00' f O.0loC. were determined with a 25-ml. pyrometer. Throughout t h i s work t h e concentration of solution is s t a t e d a s grams per 100 grams of solution, which is very close t o t h a t of grams per 100 ml. of solution commonly used i n v i s c o s i t y s t u d i e s , b e c a u s e t h e density of t h e pyridine is so near unity. 1958
Viscosity
COMPARISON SOLUTION
OF
VISCOSITIES
OF
PINE
WOOD
LIGNIN
T h e laboratory-determined concentration, s p e c i f i c gravity, and viscometer flow time of the lignin solutions tested, with five c a l c u l a t e d v i s c o s i t y relationships, a r e given in T a b l e I. T h e relative viscosity, Nr and t h e s p e c i f i c visc o s i t y a r e relations of the viscosity of t h e solution t o that of t h e solvent (Equations 1 and 2). CHEMICAL AND ENGINEERING DATA SERIES
129
I 0.3
I
1
I
0.6
0.0
I 2
I 1.8
I 5
I
1 2.1
2.4
2.7
CONCENTRATION. #/I% SOLUTION CONCENTRATION,
2. Specific v i s c o s i t y
Figure
Figure
VS. concentration of pyridine pine wood l i g n i n solutions
3000
PINEWOOD
OXIDIZED
SOLUTION
Logcrithm of r e l a t i v e v i s c o s i t y VS. concentration o f pyridine pine wood lignin solutions
03
I
I
3.
4 /io04
LIGNIN
0 30
ZOO0 MOLECULAR WEIGHT OF
I
I
I
I
CETONE
SOLUBLE
METHANOL SOLUBLE
FRACTION
0 06
ow SPECIFIC
OF
FRACTION OF
I
0 03
I
LIGNIN LIGNIN
I
0 le
VISCOSITY
PINEWOOD
PINEWOOD
0 15
0 I0
0.21
I?. S O L U T I O N S
OF
L
I 0.3
0.6
I
I
0.0
1.e
CONCENTRATION,
F i g u r e 4. Empirical r e l a t i o n s o f molecular weight of l i g n i n s to specific v i s c o s i t y o f 1% solutions
Specific viscosity (N P'
viscosity of solution
-
viscosity of solvent ) = Nr 1
-
( 1)
(2)
For comparative purposes the specific v i s c o s i t i e s of the solutions of lignins are plotted against concentrations in Figure 2, and in Figure 3 the logarithms of the relative viscosities divided by the concentration a r e plotted against concentration.
130
I N D U S T R I A L AND E N G i N E E R l N G C H E M I S T R Y
1.8
I
I
I
2.1
2.4
2.7
SOLUTION
Figure 5. Specific v i s c o s i t y VS. concentrution o f pyridinelignin and water-lignosulfonate solutions
Prepared from data of Staudinger and Dreher (J), assuming all values were straight-line functions
Relative viscosity (Nr) =
f,/lGU~
1 1 5
T h e differences in t h e viscosities of the lignin materials shown in T a b l e I and Figures 2 and 3 suggest differences in chemical structure. T h e s e may be due entirely t o differe n c e s i n molecular weights, In general, the materials of lower molecular weight are more soluble in organic solvents than homologous materials of greater weight. T h i s could explain the lower v i s c o s i t i e s of the solutions of t h e solventseparated lignins and the greater v i s c o s i t i e s of t h e solutions of the oxidized lignin. One theory of the oxidation of such lignins from kraft liquors proposes that oxidation occurs VOL. 3, NO. 1
between t h e mercaptan groups of e a c h of two molecules of lignin and t h u s molecules of greater size a r e formed. T h e lower v i s c o s i t i e s of t h e solutions of t h e pyridine-soluble portions of t h e acetone- and methanol-insoluble fractions of t h e lignin would be expected. If s o l u t i o n s were prepared of t h e pyridine-insoluble materials of t h e s e fractions, their v i s c o s i t i e s would probably b e greater than t h a t of t h e unchanged p i n e wood lignin in t h e same solvent. INDICATED MOLECULAR WEIGHT O F LIGNIN MATERIALS
In a s t u d y of lignins isolated from wood by phenol and resorcinol it w a s noted t h a t t h e s p e c i f i c v i s c o s i t i e s of t h e chloroform s o l u t i o n s of t h e s e lignins a t concentrations of 1%or below w e r e directly proportional t o t h e concentrations and t h a t viscosity-concentration curves were linear (6). T h e s p e c i f i c v i s c o s i t i e s of t h e s e s o l u t i o n s a t the lower concentrations were 0.030 t o 0.065. More detailed s t u d i e s of similar lignins in acetone, a c e t i c acid, and dioxane solutions (5) confirmed t h e earlier work. T h e s p e c i f i c v i s c o s i t i e s of 1%s o l u t i o n s of phenol lignin, acetylphenol lignin, o-cresol lignin, a c e t y l - e c r e s o l lignin, beechwood lignin, and a sodium lignosulfonate i n acetone and a c e t i c a c i d were from 0.030 t o 0.065. T h e s e v a l u e s corresponded very c l o s e l y t o t h a t of c e l l o p e n t a o s e a c e t a t e , w h o s e molecular weight w a s 1542. A lignin obtained by digestion of s p r u c e wood in concentrated formic a c i d g a v e a molecular weight of 1000 by freezing point depression of dioxane. T h e s p e c i f i c v i s c o s i t y of a 1%solution of t h e s a m e lignin in dioxane or formic a c i d w a s 0.065 t o 0.070. By using t h e molecular weight of t h e formic acid s p r u c e lignin a s 1000 and i t s specific viscosity of 0.065, and assuming t h e weight-viscosity relationship to b e a straight-line function, F i g u r e 4 w a s prepared. From F i g u r e 2 s p e c i f i c v i s c o s i t i e s at 1% concentration were obtained and a r e indicated on F i g u r e 4. T h e molecular weights a s indicated i n F i g u r e 4 vary from 900 t o 2900. In a s t u d y of native black spruce lignin, t h e v i s c o s i t i e s
of some d i l u t e solutions of t h e lignin in dioxane were determined (2). Various fractions of the lignin having molecular w e i g h t s estimated a t 2800 t o 5800 were studied. T h e reduced v i s c o s i t i e s ( s p e c i f i c v i s c o s i t y per unit concentration) of 1 and 2% solutions varied from 0.05 t o 0.10. C a l c u l a t i o n s of t h e reduced v i s c o s i t i e s of t h e pine wood lignin-pyridine s o l u t i o n s from t h e c u r v e s of F i g u r e 2 give v a l u e s of 0.06 t o 0.23. A s u m i n g t h e s p e c i f i c viscosityconcentration relationships for t h e native black spruce lignin-dioxane s o l u t i o n s and t h e pine wood lignin-pyridine solutions a r e comparable, i t a p p e a r s that t h e two lignins a r e of about t h e s a m e molecular weight. T h e v i s c o s i t i e s o f s o m e dilute s o l u t i o n s of purified (by exhaustive dialysis) sodium lignosulfonates and lignin sulfonic a c i d s from a sulfite w a s t e liquor have been determined (1). T h e s p e c i f i c viscosity-concentration relations h i p of t h e s e aqueous s o l u t i o n s w a s shown t o be a lineal function. A plot of t h i s viscosity-concentration relationship is shown in Figure 5 , with similar p l o t s of l i k e v a l u e s of solutions of t h r e e pine wood lignins. T h e two t y p e s of lignins appear t o have molecular weights of t h e s a m e magnitude. Estimated molecular weights of 3000 t o 20,000 h a v e been obtained for lignosulfonates f r o m s p e n t s u l f i t e liquors by c a l c u l a t i o n s f r o m light-scattering measurements (3) and determinations of diffusion coefficients (4). L I T E R A T U R E CITED (1) Heister, K., McCarthy, J. L., Benson, H. K., Zbid., 126, 58-61 (1948). (2) H e s s , L., TAPPZ 35, 312-319 (1952). (3) Moacanin, Jovan, Felicetta, V. F.,Haller. Wolfgana, McCarthy, J. L . , J . Am. Chem. S O C .77, 3470-75 (1955). (4) Olleman, E. Ritter, D. M ,Zbid., 69, 665 (1947). (5) Staudinger, H.,Dreher, E., Ber. 698, 1729-37 (1936). (6) Wedeking, E., Engel, O., Storch, K., Tauber, L., Cellulosechemie 12, 1163-73 (1931). Received for review December 3, 1956. Accepted August 29, 1957. Division of Cellulose Chemistry, Lignin Symposium, 130th Meeting, ACS, Atlantic City, N. J., September 1956.
W e a t h e r i n g of Poly (vinyl Chloride) Effect of Composition J. 6. DeCOSTE, J. 6. HOWARD, and V. T. WALLDER Bell Telephone Laboratories, Inc., Murray Hill, N. J.
P l a s t i c i z e d poly(viny1 chloride) (PVC) is being used i n a n increasing number of outdoor applications, particularly in t h e outside telephone plant, where it a p p e a r s a s extruded wire coatings, injection molded parts, and dispersion coati n g s on textiles. Serviceable outdoor compositions a r e p o s s i b l e through t h e judicious c h o i c e of s t a b i l i z e r s and pigments (8). T h e s e r i e s of colored poly(viny1 chloride) c o a t i n g s used on t h e two new t y p e s of outdoor telephone wire known as B Urban and B Rural Wire a r e practical applications of t h e s e principles (20). On t h e b a s i s of a 4year study in Florida, a minimum outdoor life of 10 y e a r s h a s been predicted by G r i e s s e r and Higgins (15) for properly pigmented materials. Poly(viny1 chloride) p l a s t i c s a r e not inherently weatherr e s i s t a n t and derive their properties in t h i s r e s p e c t mainly through formulation. T h e purpose of t h e present s t u d i e s h a s been t o a s s e s s t h e e f f e c t s of weathering on various r e s i n s , p l a s t i c i z e r s , and light absorbers. Through work of 1958
t h i s kind, it is hoped to accumulate technical d a t a useful in formulating outdoor compositions d e s i e n e d for s p e c i f i c applications. T h e formulations reported h e r e a r e not intended for any s p e c i f i c applications, however, and should be viewed only as v e h i c l e s in which t h e variables a r e being investigated. .As t h e s a m p l e s weathered, their attrition w a s followed primarily by t h e measurement of physical properties. Natural weathering w a s u s e d exclusively, with d i v e r s e climates, t o obtain the maximum p o s s i b l e effect. MATERIALS
T h e mixing procedures were e s s e n t i a l l y t h o s e followed in t h e previous investigation (8). Compositions were mixed on hot rolls and press-molded to t e s t s h e e t s 0.030 inch thick, e x c e p t where noted. T h r e e s e r i e s of experimental compositions were studied i n which t h e resin, plasticizer, and organic ultraviolet absorber were varied. CHEMICAL AND ENGINEERING D A T A SERIES
131
