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21 Physical Properties of Blends of Poly(vinyl
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Chloride) and a Terpolymer of Ethylene E. W. ANDERSON, H . E. BAIR, G. E. JOHNSON, T. K. KWEI, F. J. PADDEN, JR., and DENISE WILLIAMS 1
Bell Laboratories, Murray Hill, N J 07974
The compatibility of blends of poly (vinyl chloride) (PVC) and a terpolymer (TP) of ethylene, vinyl acetate, and carbon monoxide was investigated by dynamic mechanical, dielectric, and calorimetric studies. Each technique showed a single glass transition and that transition temperature, as defined by the initial rise in E" at 110 Hz, e" at 100 Hz, and C at 20°C/min, agreed to within 5°C. PVC acted as a polymeric diluent which lowered the crystallization temperature, T , of the terpolymer such that T decreased with increasing PVC content while T increased. In this manner, terpolymer crystallization is inhibited in blends whose value of (T — T ) was negative. Thus, all blends which contained 60% or more PVC showed little or no crystallinity unless solvent was added. p
c
c
g
c
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T> y blending with any one of a multitude of additives, P V C can be ^ transformed into a broad spectrum of resins ranging from highly plasticized to impact resistant. T h e use of polymeric plasticizers has attracted a great deal of attention because they provide superior permanence i n physical properties over their low molecular weight counterparts. Recently a terpolymer of ethylene, vinyl acetate, and carbon monoxide was reported to be miscible with P V C ( 1 , 2 ) . T h e system is of interest because blends of P V C and ethylene-vinyl acetate copolymers range from incompatible to miscible, depending on the content of vinyl acetate in the copolymer (3,4,5). W e have therefore undertaken x-ray, 1
Present address: University of Massachusetts, Amherst, MA 01002. 0-8412-0457-8/79/33-176-413$05.00/0 © 1979 American Chemical Society In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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morphological, calorimetric, dielectric, and dynamic mechanical studies to elucidate the compatibility and physical properties of blends of P V C with the terpolymer. A second objective of this study concerns the crystallization of the terpolymer i n the mixture. W h i l e the terpolymer acts as a plasticizer for P V C , the latter also can be viewed as a polymeric diluent which influences the crystallization of the former. The melting point of the terpolymer, about 77°C, is slightly lower than the glass transition tem perature of P V C , and it is conceivable that a mixture containing a minor quantity of the terpolymer can have a glass temperature approaching or exceeding the crystallization temperature of the terpolymer i n the mix ture. One would then expect the crystallization process to be retarded or inhibited by the highly viscous matrix. If, however, the T of the mixture is lowered by the addition of a solvent, then crystallization still may be able to proceed. W e have conducted preliminary experiments to explore this possibility. g
Experimental Materials. P V C , Geon 103 E P from B. F . Goodrich C o . , and a terpolymer, Elvaloy 741 from Ε . I. d u Pont de Nemours and Co., were used. Blends of the two polymers were mixed on a two-roll mill at 160°C and then pressed into films on a heated press at 150 °C. The compositions of the mixtures are reported as weight percentages i n our text. X-Ray and Light Microscopy. X-ray diffraction patterns of pow dered specimens of Elvaloy 742 and its blends with P V C were recorded on photographic films in a G u i n i e r - D e W o l f f focusing camera. Light microscopy was performed on a Reichert Zetopan polarizing microscope with a Mettler FP21 hot stage. Dynamic Modulus. Measurement of dynamic viscoelasticity was made by the use of a direct-reading dynamic viscoelastometer from the Toyo Measuring Instrument Co., at a frequency of 110 H z . Tensile Strength. The tensile strength and elongation of the two polymers and their blends were measured at room temperature with a table model, Instron tensile tester at a strain rate of 111 percent per minute. Calorimetry. Glass and melting transitions and apparent heats of fusion ( A Q f ) were analyzed by a differential scanning calorimeter, Perkin-Elmer D S C - 2 . Measurements were made i n a helium atmosphere at a heating or cooling rate of 40°C/min i n a manner which has been reported elsewhere ( 6 ) . Where accurate absolute values of heat capacity ( rather than merely the change i n C ) are desired, a Scanning Auto Zero accessory was used to produce an essentially flat baseline from — 100° to 150°C. Heat-capacity calculations were performed by a Per k i n - E l m e r programmable calculator system which includes a Tektronix Model 31 calculator. In these measurements, the heating rate was 20°C/ min. The heat capacities of a standard A 1 0 sample i n the temperature range of —30° to 120°C were found to be within 1 % of the values re ported i n the literature ( 7 ) . p
2
3
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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Polyvinyl Chloride)
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Dielectric Properties. Dielectric measurements were conducted at ΙΟ , ΙΟ , 10 , and 10 H z . The data were obtained by combining a Prince ton Applied Research 124 lock-in amplifier and a General Radio 1615A capacitance bridge. The bridge was connected to a Balsbaugh L D 3 research cell inside a test chamber. Temperature was monitored with a thermocouple taped to the cell. After the chamber was equilibrated at —160°C for 1 hr, measurements were made at approximately 10°-inter vals with a 15-min waiting period between each temperature change. Downloaded by KTH ROYAL INST OF TECHNOLOGY on October 29, 2015 | http://pubs.acs.org Publication Date: June 1, 1979 | doi: 10.1021/ba-1979-0176.ch021
2
3
4
5
Results X-Ray Studies. Lines in the x-ray, powder diffraction pattern of the terpolymer were similar to those found in polyethylene (PE). Since the terpolymer contains a majority of ethylene segments, we assumed that it crystallized in an orthorhombic unit cell as polyethylene does. The lattice parameters for the terpolymer were calculated to be a = 7.76 A , b = 5.06 A , and c = 2.56 A . These values are to be compared with the dimen sions of P E unit cell: a = 7.40 A , b = 4.93 A , and c = 2.54 A (8). Thus x-ray data suggest that the terpolymer crystallizes with an expanded P E unit cell. The low intensity of the x-ray lines found i n the diffraction pattern of the terpolymer compared with the high intensity observed for P E signified that the level of crystallinity in the former was significantly below that of P E . In spite of this, an amorphous sample could not be prepared by quenching. The presence of crystalline regions was indi cated in many mixtures, but crystallinity decreased markedly as the weight fraction of the terpolymer decreased. Light Microscopy. Although films of the terpolymer were biréfringent, no spherulites could be detected regardless of the manner i n which specimens were prepared. Samples cast from a 2 % solution in tetrahydrofuran ( T H F ) and annealed at 60°C overnight had optical melting points which ranged from 63° to 75°C. Dynamic Viscoelasticity. The dynamic modulus and loss tangent curves are shown in Figures 1, 2, and 3. The E" peak temperature of the main transition in P V C occurs at 90°C; the secondary transition, which has been ascribed to local mode motion of the P V C main chain, extends from - 1 2 0 ° to 40°C, with a maximum located at about - 3 0 ° C . These results are in good agreement with earlier investigations (9). The terpolymer has a sharp glass transition near —22°C; the γ relaxation in the neighborhood of —135 °C occurs at a lower temperature and is broader than the corresponding relaxation in linear or branched polyethylene (9). The blends show three regions of mechanical relaxation. The low temperature dispersion near — 135°C, characteristic of the terpolymer, remains prominent. F o r each mixture, a single loss maximum above 0 ° C is accompanied by an abrupt decrease in £ ' and is undoubtedly associated
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
416
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MULTIPHASE
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Τ (°C) Figure 1.
The storage and loss modulus curves for the terpolymer and PVC
with the glass transition of the mixture. I n the region between —20° and — 80 °C, where the local mode motion of P V C occurs, the loss tangent curves are almost flat. This observation suggests that the local environ ment of P V C segments has been influenced by the terpolymer as a result of extensive mixing. The flat region also appears to shift to a lower temperature and covers a narrower temperature span as the amount of
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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Poly (vinyl Chloride)
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terpolymer increases. Similar results were reported in blends of P V C with a copolyester of poly ( tetramethylene ether ) glycol terephthalate and tetramethylene terephthalate ( J O ) , poly(c-caprolactone (11 ), ethylene-ethyl acrylate-carbon monoxide terpolymer (12), ethylene-N,I\Fdimethylacrylamide copolymer (13), and ethylene-vinyl acetate copoly mer (4).
i | Q
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I
I
-160
-120
-80
8
I
I
-40
0
I
40
1
80
120
T(°C)
Figure 2. Temperature dependence of dynamic-mechanical properties for 60 TP/40 PVC (O), 40 TP/60 PVC (Φ), and 20 TP/80 PVC (-)
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
MULTIPHASE
POLYMERS
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418
Dielectric Measurements. The dielectric loss ( e" ) curves at different frequencies for samples containing 100, 80, 40, and 0 % P V C , respectively, are shown in Figures 4, 5, 6, and 7. Figure 8 is a composite of the dielectric loss data at 1 kHz for each sample. The general characteristics of a and β relaxation peaks of the component polymers and their mixtures parallel the results of dynamic mechanical measurements. F o r each
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
21.
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Poly(vinyl Chloride)
A L .
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100 TP
400 Τ (°C) Figure 4.
Temperature dependence of the dielectric loss behavior from 10 toiœHz of the terpolymer (100 TP) 2
mixture, a single a peak was detected. It is noticed, however, that the a transition of the 8 0 % P V C sample is broader than that of the 4 0 % P V C sample and that small shoulders between — 20° and — 80°C are observed for the former at 10 and 10 H z . These results are again i n harmony with the viscoelastfc data. Calorimetry. Prior to C measurements, each sample was heated to 140°C and then cooled at a rate of 40°C/min to — 90°C unless otherwise stated. Measured C values are listed i n Table I. 2
3
p
p
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
MULTIPHASE
POLYMERS
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420
The Cp of P V C (lower curve i n Figure 9) increases linearly with temperature from - 60° to 80°C. Between 85° and 93°C, the glass transition is manifested by a discontinuous increase in C and corresponds to the a transition observed in the dielectric and dynamic mechanical experiments. Above the glass-transition temperature, C increases smoothly to 120°C where the experiment was terminated. p
p
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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ANDERSON E T
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Poly(vinyl Chloride)
The C curve of the terpolymer (upper curve Figure 9) is more complex. It rises smoothly from - 120° to - 40°C but above - 34°C increases abruptly, and a broad endothermic peak, typical of fusion of polymer crystals, occurs between 50° and 77°C. W e attribute the initial discontinuity i n C at — 34°C to the onset of glass transition and the subsequent increase in C to melting. The point of inception of melting of terpolymer crystals can be estimated by extrapolating the C curve p
p
p
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p
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2
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I -100
I 0
100
Τ (°C) Figure 6.
Temperature dependence of the dielectric loss behavior from KPtolPHz of the 20 TP/80 PVC
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
422
MULTIPHASE
1.0
I
I
POLYMERS
I ηΛίΟ
100 PVC
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100
Τ (°C) Figure 7.
Temperature dependence of the dielectric hss behavior from 10 to 10 Hz of the PVC (100 PVC) 2
s
of the liquid between 80° and 150°C to lower temperatures until it intersects the C curve at about — 15 °C. The broad temperature range of fusion, from — 15° to 77°C, most likely reflects the presence of lamellae of varying thickness or defects. Accepting the above interpre tation, we estimate the apparent heat of fusion, AQ , from the area of p
t
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
21.
ANDERSON
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Polyvinyl Chloride)
423
the C curve between the inception of melting at — 15°C and its termination at 77°C. The value of AQ is 8.3 cal/g. (As a point of reference, the heat of fusion per crystallized unit is about 68 cal/g for linear polyethylene (14,15).) Slow cooling from the melt at 0.31°C/min results i n only minor changes in the C curve. Annealing of a quenched sample near its T , on the other hand, produces noticeable differences i n the thermal scan. p
t
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p
Figure 8. Temperature dependence of dielectric loss behavior at 1 kHz for PVC (A), 20 TP 180 PVC (O), 60 TP/40 PVC (Φ), and TP (X)
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
g
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MULTIPHASE
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A melted sample of the terpolymer was cooled i n the calorimeter at 320°/min to - 40°C and was allowed to remain at - 40°C for 16 hr after which the temperature was lowered to — 150°C. Upon reheating, the Τ of the annealed sample increased to — 31 °C; moreover, an addi tional adsorption of thermal energy was superimposed upon the normal increase i n C during the glass transition. The additional increase i n en thalpy, 0.5 cal/g, is the result of enthalpy relaxation occurring during g
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p
Table I.
Heat Capacity of T P and P V C and T w o Blends
β
Cpfcal g' K ) 1
100 TP
1
60 TP/40 PVC
40 TP/60 PVC
100 PVC
0.261 0.266 0.274 0.284 0.289 0.298 0.309 0.316 0.335 0.358 0.371 0.369 0.361 0.362 0.377 0.406 0.441 0.476 0.506 0.527 0.534 0.513 0.469 0.445 0.445 0.448 0.451 0.454 0.456 0.459 0.462
0.212 0.216 0.223 0.228 0.235 0.239 0.247 0.250 0.255 0.262 0.267 0.275 0.285 0.300 0.306 0.319 0.325 0.334 0.342 0.354 0.368 0.385 0.401 0.409 0.406 0.398 0.397 0.401 0.404 0.409 0.412 0.414 0.417 0.420
0.170 0.173 0.176 0.180 0.182 0.184 0.186 0.187 0.191 0.195 0.196 0.200 0.204 0.208 0.209 0.213 0.215 0.219 0.222 0.226 0.230 0.234 0.238 0.242 0.247 0.251 0.257 0.264 0.282 0.319 0.341 0.345 0.350 0.356
T(K) 215.0 220.8 225.7 230.6 234.6 240.5 245.9 248.9 254.9 260.8 263.8 269.7 275.6 281.6 284.5 290.5 293.4 299.4 305.3 311.3 317.2 323.1 329.1 335.0 341.0 346.9 352.8 358.8 364.7 370.6 376.6 379.6 385.5 391.4 β
0.278 0.288 0.296 0.306 0.316 0.338 0.354 0.372 0.409 0.438 0.453 0.481 0.508 0.532 0.542 0.562 0.572 0.600 0.621 0.630 0.643 0.655 0.691 0.737 0.763 0.701 0.538 0.513 0.514 0.517 0.519 0.520 0.522 0.524
All samples were quenched from 400 to 200 Κ a t a cooling rate of — 1 6 0 K min" . 1
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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Poly(vinyl C Monde) T{°C)
0.80
-50 ο • • •
100
50 Γ
I
TP 6 0 Τ Ρ / 4 0 PVC 4 0 T P / 6 0 PVC PVC
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0.60 ffP^a
ι
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ο ο ο CL
ο 0.40
0.20 240
280
320
360
400
T(°K) Figure 9.
Specific heat as a function of temperature for TP, 40 TP 160 PVC, 60 TP/40 PVC, and PVC
annealing at — 40°C. W e have observed similar reduction i n excess enthalpy after annealing poly (butylène terephthalate ), a semicrystalline polymer, below its T (16). Furthermore, the annealing process caused a small increase in the amount of crystals which melted between 21° and 51°C. Annealing at temperatures near the melting point of the terpolymer also resulted i n additional features in the C curve. In Figure 10, the melting curve for a terpolymer sample with a complex thermal history is depicted. After melting, this sample was placed i n a 60°C oven for 24 hr, then cooled slowly to 40°C, and finally stored at 23°C. Although its T was unchanged at — 34 °C, the sample exhibited three melting peaks at 43°, 56°, and 72°C. The end of the fusion process occurred at a higher temperature, 92°C, than previously observed. Annealing at 20°, 40°, and 60°C for 30 min each produced crystals which melted at 30°, 48°, 67°C, respectively. Apparently each increase i n annealing temperature produced lamellae of increased thickness and correspondingly higher melting points. g
p
g
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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426
MULTIPHASE
-100
-50
0
50
POLYMERS
100
TEMPERATURE (°C) Figure 10.
C behavior of TP after annealing at 60% 40\ and 23°C p
Similar heat treatment of the blends also yielded multiple melting peaks ( Table II ). Because the specific heats of blends are influenced by the thermal histories of the samples, only two mixtures containing 40 and 60% terpolymer, respectively, were selected for quantitative C measurements. E a c h sample experienced the same thermal history as the two component polymers, namely, cooling at 40°C/min from 140° to — 90°C. The C curves of the two mixtures are also shown i n Figure 9. In the liquid state, the C of the blend was found to be the weight average of p
p
p
Table II. Elvaloy (Wt
741 %)
100 80 60 40 20 10 0 a
Thermal Properties of Elvaloy
i y
TV
TV
(°C)
(°C)
(°C)
-34 -29 -19 -6 11 41 85
43 34 27 15
77 76 73 71
— —
—
— — —
C o o l e d from melt at 4 0 ° C / m . A n n e a l e d a t 6 0 ° C f o r 24 h r , t h e n c o o l e d s l o w l y t o 4 0 ° C a n d f i n a l l y 23°C f o r s e v e r a l w e e k s . b
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
stored
at
21.
ANDERSON
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Polyvinyl Chloride)
A L .
the heat capacities of P V C and the terpolymer. F o r example, the calcu lated C of a blend of 40% terpolymer is 0.528 c a P C ^ g " at 118°C while the experimental value is 0.524 caPc^g" . Both the melting point and the apparent heat of fusion of the terpolymer decrease as the amount of P V C increases. W e made no attempt for theoretical analysis i n this regard. 1
p
1
Only a single T was detected for each blend and it increased i n temperature as the amount of P V C was increased (Figure 11). T h e value of T , however, d i d not conform to the volume-fraction average of component polymers as had been found i n poly ( vinylidene fluoride ) and poly (methyl methacrylate ) mixtures (17). The reasons are twofold; first, the composition of the amorphous portion of the terpolymer is different from that of the crystalline region. Therefore the T of the terpolymer is not representative of the overall composition. Secondly, blends containing more than 4 0 % terpolymer still retain some crystallinity even i n the quenched state. As crystallinity decreases continuously in the blend, the composition of the amorphous fraction also changes through the incorporation of more methylene units which are normally crystallizable i n the pure polymer. Consequently, the glass-transition temperatures of the mixtures do not obey simple relationships.
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g
g
g
A t this point, a comparison of the calorimetric results with dielectric and viscoelastic data, with regard to glass transitions, is in order. In both viscoelastic and dielectric measurements, the α-relaxation processes en compass both the glass transition of the mixture and the melting of terpolymer crystals, if present. Therefore, the peak position is not necessarily a good measure of the glass-transition temperature. O n the other hand, the calorimetric results are relatively free of such ambiguities. For the purpose of correlating data between these three different meas urements, we have compiled the temperatures of initial rise of E" at 110 H z , c" at 100 H z , and C at 20°C/min for these samples and plotted the p
741 and Its Blends with P V C T
m
6
TV
(°C)
(°C)
92, 74, 66, 49 79, 69,52 78,67, 52 67, 62,53 62,54 •—
79 78 — 74 74 73
0
(cal/g) 8.3 7.3 2.8 (φ) 0.6 — —
( cal/g)
( cal/g)
11.8 8.0 4.9 2.0
13.8 9.2 — 3.0 1.6 0.8
_ —
Solution crystallized.
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
428
MULTIPHASE
• E"mech. (110 Hz) ο £"elec.(100Hz ) • DSC(20°C/min)
80
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POLYMEBS
I \ \ 40
\ \
\ \
\
\
\
-40
80
100
60
40
20
%PVC Figure 11. Ύ as a function PVC concentration as defined from initial rise in Ε", ε', and C by dynamic mechanical (Π), dielectric (O), and calorimetric (Φ) measurements, respectively 0
p
values against composition in Figure 11. The agreement among the three methods is within 5°C. Although such a comparison appears obvious, we do not recall similar efforts in the literature. Crystallization of the Terpolymer in the Mixture. Crystallization of the terpolymer occurred in samples containing 60% or more of the terpolymer when cooled from the melt at a rate of 40°C/min. The specimen containing 40% terpolymer at first d i d not exhibit a measurable exotherm because of crystallization, although a small amount of crystals was detected in the sample upon subsequent reheating. Additional cool ing studies conducted at 40°, 20°, 10°, and 5°C/min on samples con-
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
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ANDERSON
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Poly(vinyl Chloride)
A L .
taining 4 0 % T P have revealed that the onset of crystallization, T , occurred at about 15°C, w h i c h was just before the sample began to undergo vitrification. Mixtures containing 20 and 1 0 % terpolymer, respectively, d i d not crystallize upon cooling from their melts. W h e n T ( determined at a cooling rate of 40°C/min) and T were plotted vs. weight percent P V C , it was noticed that the former decreased with increasing P V C content while the latter increased (Figure 12). The differences between T and T were 7 7 ° , 63°, 4 6 ° , and 21°C for samples containing 100, 80, 60, and 4 0 % terpolymer, respectively. If the T data is extrapolated linearly to other compositions, the value of c
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c
g
c
g
c
1
Γ
Wgt % PVC Figure 12.
Crystallization and ghss temperatures as a function of PVC concentration
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
430
MULTIPHASE
( T — T ) would have been 0 ° C for a 2 5 % terpolymer sample. The fact that the extrapolated T has fallen below T i n the 2 0 % T P sample probably accounts for the lack of crystallization in this sample. When the quenched samples were thermally treated at 60°C for 24 hr, they underwent further crystallization as indicated by the higher values of heat of fusion obtained in subsequent thermal scans ( Table II ). In addition to the annealing study, a second approach also was attempted. It was based on the thought that crystallization might be facilitated by lowering the T of the mixtures with a suitable solvent. Three samples were selected for this investigation, containing 40, 20, and 10% terpoly mer, respectively. The crystallization temperature was chosen to be 0 ° C because T for the 10% terpolymer sample in the bulk was estimated to be below room temperature. F o r the purpose of comparison, films con taining 80 and 100% terpolymer also were cast from solution. Our rudimentary experiments were conducted as follows: each sample was dissolved i n T H F to form a 7 % solution. A n aliquot of the solution was poured into a Petri dish which was surrounded by an icewater mixture. The content in the dish was placed under a well-venti lated hood and the solvent was allowed to evaporate. W i t h i n 15 minutes, the solution began to turn opaque, indicative of crystallization. A t the end of about one hour, the mixture was completely opaque. It still contained more than 3 0 % solvent but could be lifted from the dish as a free film. The opacity of the film was retained even after heating at 100°C overnight. c
g
c
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POLYMERS
g
g
c
I
1
!
1
600 o-PVC • - P V C / T P =80/20 * - P V C / T P = 60/40 * - P V C / T P = 40/60 PVC/TP =20/80 •-PB
500 (\J 4 0 0 e \ο σ» 300 -
-
tf
b 200 -1
—
100
-
0 0
200
400
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Figure 13.
Stress-strain curves of PVC, TP and their blends at a strain rate of 111%/min
In Multiphase Polymers; Cooper, S., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1979.
21.
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E T A L .
Polyvinyl Chloride)
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The calorimetric results of the solution-crystallized films are given in Table II. The apparent heat of fusion is enhanced for a l l films containing 4 0 % or more of T P relative to the bulk crystallized samples. In addition, the 10 and 2 0 % T P blends were found to be partially crystalline with T s only lowered by 5 ° or 6°C. Tensile Properties. Figure 13 shows the stress-strain behavior at room temperature of the two component polymers and their mixtures. The tensile properties range from rigid response for P V C to elastomeric, ductile behavior for the terpolymer. Note that the 8 0 % P V C sample exhibits a high Youngs modulus followed by extensive yielding at high stress before breaking.
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m
Conclusion The compatibility of blends of P V C and the terpolymer was investigated by dynamic mechanical, dielectric, and calorimetric studies. N o t only did each technique show a single glass transition for each mixture, but also the temperature of the transition, as defined by the initial rise in E " at 110 H z , e" at 100 H z , and C at 20°/min, agreed to within 5°C. T was found to increase with increasing concentration of P V C . Although the terpolymer plasticized P V C , the latter was found to act as a polymeric diluent which lowered the crystallization temperature, T , of the former. In this maner, the crystallization of the terpolymer could be retarded or inhibited i n blends whose value of ( T — T ) was near or below 0 ° C . Mixtures containing 6 0 % or more P V C were found to be in this category and showed little or no sign of bulk crystallization. However mixtures containing 80 and 9 0 % P V C which were completely amorphous i n the bulk, crystallized when solvent was added. Though we believe crystallization occurred because of a lowering of T , separation of this from the possibility of crystallization from solution would require further studies. p
g
c
c
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Acknowledgment The authors wish to acknowledge the valuable advice and assistance rendered by P. C . Warren and J . E . Adams in the course of this study.
Literature Cited 1. Tordella, J. P., Hyde, T. J., Gordon, B. S., Hammer, C. F., Mod. Plast. (1976) 54(1), 64. 2. Hammer, C. F., Am. Chem. Soc., Div. Org. Coat. Plast. Prepr. (1977) 37, 234. 3. Jyo, Y., Nozaki, C., Matsuo, M., Macromolecules (1971) 4, 517. 4. Hammer, C. F., Macromolecules (1971) 4, 69.
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