Acknowledgment
The authors’ thanks are due to S. K. Bhattacharyya, ExHead of the Department of Chemistry, Indian Institute of Technology, Kharagpur, for his interest in the work. L i t e r a t u r e Cited Andrew, C. E.. U.S. Patent 2 073 671 (1937). Bhattacharyya, A. K., Nandi, D. K., lnd. Eng. Chem., Prod. Res. Dev., 14, 162 (1975). Brown, A. G., Reid, E. E., J. Am. Chem. SOC., 46, 1836 (1924). Dodge, B. F., “Chemical Engineering Thermodynamics”, p 494, McGraw-Hill, New ‘fork, N.Y., 1944. Earl, J. G., Hills, N. G., J. Chem. SOC.,973 (1947). Goshorn, R. H., US. Patent 2 349 222 (1944). Hill, A. G., Shipp, J. H., Hill, A. J., lnd. Eng. Chem., 43, 1579 (1951). Inoue. H., Bull. Chem. Soc., Jpn., 1, 157 (1926).
Mailhe, A., W o n , F., Compt. Rend., 166, 467 (1918). Maxted, F. B., Brit. Patent 577 901 (1944). Nandi, D. K., Bhattacharyya, A. K., lndian J. Techno/., 13, 168 (1975a). Nandi, D. K., Bhattacharyya, A. K., J. Appl. Chem. Biotechnol., 25, 737 (1975b). Poirrier, Chappat, Bull. SOC.Chim., 6, 502 (1866). Roy, B. C., J. lndian Chem. Soc..5, 383 (1928). Shuikin. N. I., Bitkova, A. N., Ermilina, A. F., J. Gen. Chem. (U.S.S.R.), 744 (1936). Smith, J. M., “Chemical Engineering Kinetlcs”, p 25, McGraw-Hili, New York, N.Y., 1956. Stull. R. S.,Westrum, E. F.. Sinke, G. C., “The Chemical Thermodynamics of Organic Compounds”, p 688, 700, Wiley, New York, N.Y., 1969. Vogel, A. I., “A Textbook of Practical Organic Chemistry”, p 622, Longmans Green and Co., London, 1951. Vriens, G. N., Hili, A. G., lnd. Eng. Chem., 44, 2732 (1952).
Received for review February 25,1976 Accepted April 14,1976
Acid-Base Interaction in Filler-Matrix Systems Michael J. Marmo, Mohamed A. Mostafa, Hldeo Jlnnal, Frederick M. Fowkes,’ and John A. Manson Department of Chemistry and Materials Research Center, Lehlgh University, Bethlehem, Pennsylvania 180 15
The mechanical properties of solution-cast films of filled polymers are found to be very much enhanced when the polymer is strongly adsorbed on the filler in the casting solution. Acid-base interactions between polymer and filler promote such adsorption, subjectto the acidic or basic nature of the solvent. {-Potential measurements were used as a measure of acid-base interaction between filler and polymer in solvents of low dielectric constant. Thin films containing up to 60 vol % filler were cast from both acidic and basic solvents. Relative values of Young’s modulus and tensile strength were compared for each system using the equations of Kerner and Nielsen as a basis for the cases of good and poor adhesion. In a system with acidic polymer (post-chlorinated PVC) and basic filler (CaC03 or BaTi03) cast from an acidic solvent (CH2C12),both adhesion and mechanical properties were improved over the same system cast from a basic solvent (THF); adsorption measurements showed no polymer adsorption from THF, but rapid and strong adsorption from CH2C12.For the most part, in systems where both polymer and filler were either acidic or basic, brittle films (or none at all) were obtained.
Introduction
It is well known that many properties of polymers are markedly changed by the incorporation of a filler as a second phase (Fowkes, 1972; Fowkes and Hielscher, 1972; Nielsen, 1975; Manson and Sperling, 1976). For example, a t least for the case of good filler-matrix adhesion, the modulus and dimensional stability are increased, and the permeability to penetrants decreased (Nielsen, 1967; Manson and Chiu, 1973). Such effects are of great interest in engineering plastics and pigmented coatings, respectively. However, these improvements must be balanced against tendencies of the filler to decrease the elongation, toughness, and tensile strength (Nielsen, 1966). In order to optimize the balance of properties in filled plastics, and to make possible the use of even larger concentrations of cheap and non-energy-intensive inorganic fillers, much attention is being given to the control and modification of filler-matrix interaction (Modern Plastics, 1975). Examples of fortuitous or deliberate modification or selection of filler-matrix interactions abound, for example, the use of silane treatments on glass and of organic titanates on calcium carbonate. While many of these treatments may involve either an improvement in compatibility or actual reaction with the matrix, polar interactions must also be important. Following earlier work by Fowkes et al. (1970,1972) and 206
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Anderson et al. (1975) with effects of electrostatic (acid-base) interaction, a program was begun to investigate in detail the role of such interactions in optimizing mechanical and permeability behavior in particulate fillers. Results should also be of interest to the general question of adhesion between polymers and substrates. In particular, with a suitable match between an acidic filler and a basic matrix, or vice versa, it should be possible to obtain a strong but ductile filler-matrix bond, thus permitting the use of high filler contents without sacrifice of toughness. It should also be possible to thus minimize undesirable particle-particle aggregation, and also reduce the penetration of deleterious ions, such as chloride, through a protective coating. For this study, polycarbonate (PC) and chlorinated poly(vinyl chloride) (CPVC) were selected as intrinsically basic electron donors (+) and acidic electron acceptor (-) polymers, and silica, barium titanate, and calcium carbonate as nominally acidic and basic fillers. (It may be noted that both acidic and basic sites undoubtedly exist on the surface of any filler, whether it be basic or acidic overall.) Films were cast from basic and acidic solvents (tetrahydrofuran and methylene chloride, respectively, for several filler concentrations). Mechanical properties (Young’s modulus and ultimate tensile strength and elongation) were determined, .( potentials measured in some cases to indicate
trends in electrostatic interaction, rates of polymer adsorption on fillers measured in some cases, and specimens examined with the scanning electron microscope. This paper describes and discusses preliminary results and suggests future directions. Acid-Base Interactions at Interfaces. Polymers interact with their surroundings mainly by two kinds of attractive forces, London dispersion forces and acid-base interactions (Fowkes, 1972). With polymer solutions, the solubility parameter has long been used to predict and correlate the dispersion forces. Deviations are often due to specific acid-base interactions; Gardon (1966) and Hansen (1967) have proposed broadening the solubility parameter to include dipole and hydrogen-bonding interactions, but not the kind of acid-base interactions discussed in this paper. In polymer blends, dispersion forces (which hinder mixing) are overcome by specific acid-base interactions, for example in the case of (basic) poly(e-caprolactone) with (acidic) poly(viny1 chloride). In composite systems, both dispersion forces and acid-base interactions are important, with the latter believed to be especially important to adhesion. Thus, the acid treatment of aluminum has long been known to enhance the bonding to base-catalyzed epoxy resins (themselves somewhat basic). Similarly, while basic inorganic oxides in a basic polymer (PC) were shown to yield brittle and conductive films (nonrandom dispersion of filler) at a loading of 20 vol %, the same oxides gave tough, low-conductivity films when dispersed in an acidic polymer (CPVC) even at loadings of 60 vol % (Fowkes and Hielscher, 1972). Similar results were also found with PC when the filler was treated with an acid; scanning electron microscopy confirmed good adhesion and dispersion with the matched acid-base systems. It has also been noted that in such cases electrons may be injected from a basic polymer or filler 100 A or so into the acid filler or matrix, thus yielding a strong electrostatic component of adhesion (Fowkes and Hielscher, 1972). One would expect such interfaces to be both strong and ductile, for during deformation polar bonds will be not only broken (requiring much energy) but also reformed (compare the case of ionomers, in which the polar interactions yield a high degree of reinforcement without requiring crystallinity in the polymer.) In this paper, we are concerned with properties of cast filled polymer films, but many of these properties are already determined in the fluid dispersion prior to film casting. In preparation of the dispersion large clumps of filler particles are milled into a polymer dispersant solution; in our work the polymer was used as dispersant. In the milling process large clumps of filler particles are broken into smaller clumps which tend to quickly reflocculate into large clumps. This cyclic process continues unless the reflocculation process can be slowed by the adsorption of polymer or dispersant during the brief period before reflocculation (on the order of seconds, according to the Smolukowski theory of rapid ffocculation). Obviously rapid adsorption is required in the production of fine dispersions and prevention of clumping, but rapid adsorption is seldom observed unless acid-base interaction occurs during absorption. At 25 “C, most surfactants and polymers require several hours to adsorb a complete monolayer on solid surfaces, but when the polymer is acidic and the filler basic (or vice versa) the adsorption times can be reduced to minutes or seconds (Fowkes, 1960). Thus acid-base interactions between polymer and filler surface are necessary to get filled polymers without clumps of filler, especially when the volume fraction of filler is high. The role of solvent in the dispersion process can be quite important when the solvent has acidic or basic properties, for the solvent can compete with either the filler or the polymer and decrease the interaction. In this paper we illustrate this
point by comparing results with an acidic solvent and with a basic solvent for the same filler-polymer combination. Quantitative characterization of acid-base interaction or organic molecules can now be done by using the Drago cotrelations (Drago et al., 1971). These findings are useful for estimating acid-base interactions between polymers and solvents (Fowkes, 1972), but filler surfaces have not yet been sufficiently characterized. One method of illustrating acid-base interaction between filler and solvent, and between filler and dissolved polymer, is to determine the size and magnitude of charge transfer. One can use electrodeposition or electrophoresis (Van der Minne and Hermanie, 1952; Koelmans and Overbeek, 1954). It is quite clear that in liquids of low dielectric constant that charge transfer between proton donors and acceptors can be explained by proton transfer from the acidic filler to the basic polymer (or vice versa) (Fowkes et al., 1965; Fowkes, 1966; Tamarabuchi and Smith, 1966). We observe how the addition of a polymer changes the extent of charge transfer as measured by electrophoresis, and a large change in charge transfer is clear evidence for strong acid-base interaction. Mechanical Properties of Filled Polymers. With thermoplastics, one of the most useful expressions to account for the stiffening effect of particulate fillers in strongly adherent systems is Kerner’s equation (1956) -E=,
E,
G p f [ ( 7- 5v)Gp GPuf[(7- 5v)GP
+ (8 - 10v)GfI + uP/[15(1- v)]
+ (8 - 10v)G~I+ uP/[15(1 - V I ]
(1) where E is Young’s modulus, v is Poisson’s ratio, u is volume fraction, and the subscripts c, p, and f refer to the composite, polymer, and filler, respectively. If the adhesion is poor, then the modulus is reduced approximately in proportion to the vf
_ -- 1 - u f EC EP
Thus, the modulus is increased predictably if the fillermatrix adhesion is good, but decreased if it is not. For the purposes of this paper, eq 1 and 2 will be used to represent the bounds of good and poor adhesion. The question of tensile strength and ultimate elongation is more complex. For the sake of simplicity, the model of Nielsen (1966) is adopted. The reduction in elongation due to the presence of a well-bonded filler tends to decrease the stress at break while the increase in E due to the filler tends to increase it. (3) UB,
=E c ~ ~ c
(4)
where UB is the ultimate tensile strength, UB is the elongation at break, and E is Young’s modulus. In this paper, E , is given by eq 1. In any case, at all values of vfencountered, the maximum value predicted for UB is never higher than that for the unfilled polymer (which might also be used to give an upper bound). For the case of poor adhesion, we have the following approximation (Nielsen, 1966) UBclUBp E
(1 - v$’3)s’
(5)
where S’ is the stress concentration factor (taken to be equal to 1 in this case) and the other symbols are the same as in eq 3 and 4. Again we have reasonable bounds to indicate the cases of good and poor adhesion between the filler and the matrix. Adsorption. The structure of cast films of filled polymer is strongly dependent on the structure of the suspension of filler particles in the polymer solution. If particles in the Ind. Eng. Chem., Prod. Res. Dev., Vol.
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207
sorption, but as adsorption of polymers is a dynamic process (in which polymer molecules are continually being adsorbed and desorbed) the desorbed molecules often carry a charge off into solution and leave the solid with the opposite charge. By this mechanism acidic polymers always confer a positive charge on particles, and basic polymers always confer a negative charge on particles (see Figure 1).This is just the opposite result from that which is observed in liquids of high dielectric constant (such as water, in which acidic polymers adsorb as anions to confer a negative charge on particles).
BASIC
DISPERSING MEDIM
t
ACIDIC
D 1SPERS I NG FED I UM /
ACIDIC PARTICLES
BASIC PARTICLES
Figure 1. Mechanism of electrostatic charging of suspended acidic particles (AH) by basic polymeric dispersants (B)in solvents of low dielectric constant.
suspension are heavily coated with adsorbed polymer, there will be few particle-particle contacts in the film and the strong polymer-filler interaction should result in improved mechanical properties. Acid-base interactions promote both the amount and the rate of adsorption (Fowkes, 1960), but these will be strongly dependent on the choice of solvent. For instance, basic solvents are better solvents for acidic polymers (such as T H F for CPVC), but the acidic polymer may interact so strongly with the basic solvent that it will not adsorb on the basic filler. The { Potential. When acid-base (donor-acceptor) interactions occur between filler surfaces and polymer molecules in solution, the result is an electrostatic charge q on the filler particles which is determinable from electrophoresis measurements. The electrophoretic mobility (p,in units of meters/second per volt/meter) is related to the charge q of spherical particles of radius r as follows (for suspensions of very low conductivity) (6) 6nr 7 The {potential a t the surface of such particles ({, in volts) is given by p=-
(7)
where to is the permittivity of free space, c is the relative permittivity (dielectric constant) of the medium, and 7 is the viscosity of the medium. The mechanism of charging particles in a liquid of low dielectric constant (c < 5) has been established as proton transfer (i.e., from the acidic surface to the basic polymer) (Fowkes et al., 1965; Fowkes, 1966; Tamaribuchi and Smith, 1966). The polymer interacts with the surface during ad208
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Experimental Section Materials. The polymers used, polycarbonate (Lexan 145) and chlorinated poly(viny1 chloride) (Hi-Temp Geon 603X560), were supplied by the General Electric Corp. and the B. F. Goodrich Co. respectively. The fillers used had the following characteristics: barium titanate (Research Organic/Inorganic Chemical Corp.), nominal purity of 99.5%, average particle size, 3 pm; calcium carbonate (Camelwite, Campbell Calcium Carbonate Products) average particle size, 3 pm; fumed silica (Aerosil380,Degussa Corp.), average particle size, 0.007 p. Tetrahydrofuran, dioxane, and methylene chloride (Fisher Scientific Co.) were reagent grade. Following common procedure (Burrell, 1975), fillers and solvents were used as received for these exploratory studies. Film Preparation. Solutions were prepared and cast in the following manner. Polymer was first dissolved in the appropriate solvent and the desired weight of filler added. (For comparison of properties, filler concentrations were calculated as volume percent, assuming additivity of densities.) All solutions were 1090solids by weight unless noted otherwise. The solutions were ball-milled for 24 h using 3-mm glass beads. Samples and unfilled controls were cast in flat-bottomed glass dishes on a leveled surface to assure uniform thickness (to within 10%;average between 2 and 15 mil). As expected, the rate of solvent evaporation was found to be extremely important. For instance, with CPVC in a volatile solvent as methylene chloride, a high evaporation rate resulted in the aggregation of filler particles and a high degree of surface roughness (Benard cell formation). To minimize such problems by controlling evaporation rate, a large desiccator partially filled with solvent was used. Polycarbonate films, on the other hand, were cast in air to prevent the induction of crystallization in an otherwise amorphous film, due to a slow rate of evaporation. (Even so, crystallization did occur, shown by microscopic examination using plane polarized light.) In all cases films were air-dried at room temperature to constant weight. When desired, additional drying was effected at 40 “C under vacuum. SEM micrographs were made of fracture surfaces on films using an ETEC instrument. Mechanical Measurements. Mechanical measurements were made using an Instron Tensile Testing machine. Test specimens were cut according to ASTM standard D638 and conditioned at room temperature for at least 40 h prior to testing (rate, 0.1 in./min). The ultimate tensile strength, nominal percent elongation, and initial Young’s modulus were calculated from the stress-strain curves obtained. { Potentials. ( Potentials were determined from electrophoretic mobilities measured with a Rank Brothers MicroElectrophoresis Apparatus, using an especially made quartz cell of rectangular cross section (1.0 X 0.0667 cm) (Parfitt, 1968; Parriera, 1969) in which velocities were measured at various distances d from the center of the cell and then plotted as a function of ( d / b ) 2 (where b is half the width of the cell) to give the familiar Van Gils plot (Van Gils and Kruyt, 1937) for averaging electrophoretic velocities, and for correcting for electroosmotic counterflow (which is zero at ( d / b ) * = 0.36) (Komogata, 1933). For each determination of {potential six particle velocities were measured. Viscosities of polymer so-
C&O ,I CW c OlOMkE
P
w
I
,I
01
!
Y
POLYMER CONCENTRATION (C/1w ML)
-20
b
0
0.2
0.4
0.6
MOLIN/P.C.
VOLUXE FRACTlOll F l L L t R c342c12
Figure 2. Observed {potentials of f i e r particles in polymer solutions (at 25 "0.
Figure 4. Effect of filler content on ultimate tensile strength (code designations as in Table I).
lutions (needed to calculate {) were measured with an Ostwald viscometer. Adsorption Measurements. Rates of adsorption of CPVC on calcium carbonate were measured at several ratios of polymer to calcium carbonate. The filler was ball-milled in the solvent overnight and was then added to a stirred solution of polymer. Aliquots of suspension were removed a t periods of 10 to 100 min after mixing, were centrifuged, and 10 ml of the supernatant was dried to constant weight. The surface area of the filler was 2.9 m2/g by Nz adsorption, and polymer adsorption is reported in units of mg/m2.
E
D C
F F-0
I
I
0
G-&2
I 0.2
I 0.4
I
0.6
VOLW FRACTION FILLER
Figure 3. Effect of filler content on Young's modulus (code designations as in Table I).
Results a n d Discussion Acid-Base Interactions of Fillers a n d Polymers. Potentials of fillers in polymer solutions of low dielectric constant (Figure 2) demonstrate that post-chlorinated PVC is a strong enough electron acceptor to confer a large positive {potential on particles of CaC03, and that polycarbonate is a strong enough electron donor to decrease by 80 mV the positive { potential conferred on particles of kaolin and CaC03 by CHzClz (an electron-accepting solvent). Rates of Adsorption. The effect of solvent on adsorption of post-chlorinated PVC on particles of CaC03 was determined with an acidic solvent (CHZClz) and with a basic solvent (THF). This acidic polymer adsorbed very rapidly out of the acidic CHzCl2 onto the basic particles of CaC03 (over 0.5 mg/mz in 20 min), but even after 100 min no adsorption of CPVC onto CaC03 from T H F could be observed. Probably the polymer had more acid-base interaction with T H F than it could have when adsorbed on CaC03. General Observations on Films. With two exceptions films suitable for testing were obtained only with cases in which an acidic filler was coupled with a basic matrix, or vice Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 3. 1976 209
b
a
d
e
C
f
g
Figure 5. Scanning electron micrographs of fracture surfaces of fiied polymer films: (a) 40% Si02/60%CPVC, CH&; (b) 40% Si02/60%CPVC, T H F (c) 40% CaC03/60%P.C., CH2C12;(d) 20% CaC03/80%CPVC, CH2C12;(e) 20% CaC03/80%CPVC, THF; (0 40% BaTiOs/60%CPVC, CH2C12;(9)40% BaTiOs/60%CPVC, THF.
Table I. Matrix-Filler Systems Rankingb Code
Combinationa
Tensile Modulus strength
CaCO-CPVC-CHzCIz (+--I 1 3 B SiOrCPVC-THF (--+I 2 1 B-Dc S102-CPVC-THF (--+) ... ... C CaCOs-PC-CHzClz (++-I 3 d 4 2 D BaTi03-CPVC-CHzClz (+--) E CaCos-CPVC-THF (+-+) 5 4 E-DC CaCOs-CPVC-THF (+-+) . .. ... F BaTiOs-CPVC-THF (+-+I 6 5 F-DC BaTi03-CPVC-THF (+-+) . .. ... Electron donor, +; electron acceptor, -; order, filler-polymer-solvent. Based on comparison at uf = 0.2. Dried to constant weight at 40 “C under vacuum. Premature failure. A
versa. In the exceptional cases both matrix and filler had the same nominal charge, but the solvent an opposite one. 0 t h erwise films were either not obtained or were excessively brittle. Brittle films were also obtained with P C in dioxane, which induced crystallization during film formation; no film was obtained with the SiOz-PC-CHzCIz system. Since the fillers varied widely in particle size and shape, rankings of systems containing different fillers should be considered as qualitative. Also, since severe packing problems 210
Ind. Eng. Chem., Prod. Res. Dev., VoI. 15, No. 3, 1976
tended to occur at u f = 0.6, greater weight should be given to the data for uf = 0.2 and 0.4. (Even so, values of E a t u f= 0.6 tended to exceed those predicted assuming poor adhesion.) Young’s Modulus. Even though the data are limited in number (Figure 3, Table I), several observations may be made. First, all systems gave values of E which exceed the values predicted by eq 2 for the case of no adhesion, or by the Sa& Furukawa relationship (1962,1963). Adaptation of the Kerner equation to such a case of a void-containing matrix would give an even lower lower-bound curve (Nielsen, 1966). Second, evidently casting from solution is highly selective, for films could not be prepared in any system in which all components were either electron donors or acceptors, and only poor films were obtained with BaTiOa (-) and PC (-1, and no film was obtained in the case of SiO;-PC-CHzCIz (+ - +) in spite of the donor-acceptor pairing of the filler and matrix. The effect of solvent is best illustrated for films of CaCOsfilled or BaTiOs-filled CPVC cast from CHzClz vs. those cast from THF. Consistently higher values of E were noted when CHzClz was used instead of THF, especially for the CaC03filled films in which a 140% increase in modulus resulted in films cast from CHzCl~(having strong polymer adsorption) as compared with a 25% increase in modulus in films cast from T H F (having no polymer adsorption). Hence, interactions between polymer and solvent play a major role in determining final composite properties. Third, gpod adhesion was observed with several systems,
as shown by the exceeding of E values predicted by Kerner's equation (1956). Although other equations may lead to higher bounds (Nielsen, 1966), still E , for the donor-acceptor pair CaC03-CPVC exceeds such values, a t least a t low volume fractions. Curiously, however, the second system that exceeds the Kerner prediction is the nominal acceptor-acceptor system SiO2-CPVC. Perhaps bonding occurs through specific donor sites on the filler, or adsorbed donor solvent serves to couple the two acceptors together. The possibility of the former effect is enhanced by the fact that in CHzClz the { potential of CaC03 decreases by 80 mV upon adding PC, and that with this system a coherent film could be cast. The question of residual solvent clearly requires more investigation. It was found that the air-dried polymer films may retain relatively large quantities (up to 9%) of THF, and that even more rigorous drying did not suffice to remove all traces. Preliminary tests with the T H F systems showed that drying to constant weight at 40 "C under vacuum resulted in a large increase in modulus for the SiO2-CPVC system, a lesser increase for BaTi03-CPVC, and inconsistent results for CaC03-CPVC. Weight losses decreased in the same order, and also with uf.However, even though some plasticization of the matrix may well exist in air-dried specimens, good adhesion was still exhibited in the paradoxically "good" SiO2-CPVC system. In any case, at low uf,most donor-acceptor pairs exhibited moduli approaching or exceeding the bound for good adhesion, and two pairs, one donor-donor and the other acceptor-acceptor, exhibited anomalously high moduli. Elucidation of the reasons for the anomalous behavior will require further studies of adsorption and of the {potential, and more detailed characterization of the balance between donor and acceptor sites on the filler particles. Tensile Strength. As might be expected, values of tensile strength, which are sensitive to the presence of stress concentrators, are more variable than values of E. Nevertheless, several of the same trends noted for E may be seen (Figure 4). If we accept the Nielsen bounds, specimens tend to exceed the bound for poor adhesion, and at uf = 0.2 exceed the bound for good adhesion, especially for the anomalous case of the acceptor-acceptor pair SiO2-CPVC. Even if we consider the upper bound to be the strength of the resin per se, the SiOzCPVC is still anomalous in its high value of strength. Again, solvents play a major role, with CHZC12 tending to give higher values than THF. Curiously, however, drying tends to lower strength in the SiO2-CPVC system but to have little effect on the others. Scanning Electron Microscopy (SEM). While a complete interpretation of fracture surface morphology using SEM is not yet feasible, strong differences between systems were often evident (Figure 5). For example (Figures 5a and 5b) with the acceptor-acceptor system SiO2-CPVC, the use of CHzC12 led
to the presence of large aggregates showing little evidence of either bonding to each other or coating by polymer; the film was too brittle to test. In contrast, the use of T H F resulted in a more uniform dispersion of filler mixed with polymer, consistent with the excellent reinforcement noted in properties. Note also (Figure 5c) that with the donor-donor system CaC03-PC, the use of CH2C12 yields a t least same bonding between filler particles. With the CaC03-CPVC pair (Figure 5d, 5e), the use of CH2C12 (which led to the highest-modulus system of all) seems to exhibit a higher level of matrix-filler adhesion than with THF. Even at uf = 0.6 (Figure 5), adhesion and deformation are clearly evident. In the case of BaTiO3CPVC (Figure 5f, 5g), again CHzClz seems to give a more uniformly dispersed material than THF, with fewer large voids. Literature Cited Anderson, H. R., Jr., Fowkes, F. M., Hielscher, F. H.. submitted, J. Poiym. Sci., 1975. Burrell, H., Prepr., Am. Chem. Soc. Div. Org. Coatings Plastics Chem., 35, 18 (1975). Drago, R. S.,Vogel, G. C.. Needham, T. E., J. Am. Chem. Soc., 93, 6014 (1971). Fowkes, F. M., J. Phys. Chem., 64,726 (1960). Fowkes, F. M., Discuss. Faraday Soc., 42,246 (1966). Fowkes, F. M., J. Adhesion, 4, 155 (1972). Fowkes. F. M., Anderson, F. W., Moore, R. J.. Preprints, 150th National Meeting, of the American Chemical Society, Atlantic City, N.J., Sept 1965. Fowkes, F. M., Hielscher, F. H., Symposium on Surface Chemistry of Composite Materials, 163rd National Meeting of the American Chemical Society, Boston, Mass., April 1972. Fowkes, F. M.. Hielscher. F. H., Kelley, D. J., J. Colloidinterface Sci., 32,469 (1970). Gardon, J. D., J. Paint Technol., 38,43 (1966). Hansen, C. M., J. Paint Technoi., 39, 104, 505 (1967). Kerner, E. H., Proc. Phys. Sci., London, 89B,802 (1956). Koelmans, H., Overbeek, J. Th. G.. Discuss. Faraday SOC., 18, 52 (1954). Komogata, S., Res. Hectrotech. Lab. Tokyo. No. 348 (1933). Lyklema, J., Adv. Coiloidlnterface Sci., 2, 65 (1968). Manson, J. A,, Chiu, E. H., J. Polym. Sci., Symp., 41,95 (1973). Manson, J. A., Sperling, L. H., "Polymer Blends and Composites," Plenum Publishing Company, New York, N.Y., 1976. "Modern Plastics Encyclopedia," McGraw-Hill, New York, N.Y., 1975. Nielsen, L. E., J. Appi. Poiym. Sci., I O , 97 (1966). Nielsen, L. E., J. Macromoi. Sci., A I , 929 (1967). Nielsen, L. E., "Mechanical Properties of Polymers and Composites," Vol. 2, Marcel Dekker. Inc., New York, N.Y., 1975. Parfitt, G. D., J. Oil Col. Chem. Assoc.. 51, 137 (1968). Parriera, H. C., J. Colloidinterface Sci., 29,432 (1969). Sato, Y., Furukawa. J., Rubber Chem. Techno/., 35, 87 (1962): 36, 1081 (1963). Tamarabuchi, K., Smith, M. L., J. Colloid interface Sci., 22,404 (1966). Van der Minne. J. L., Hermanie, P. H.,J. Co//oid Sci., 7 , 600 (1952). Van Gils, G. E., Kruyt, H. R., Kolioid-Beih., 45,69 (1937).
Received for reuiew January 6, 1976 Accepted June 2, 1976 Presented a t the Symposium on Polymer-Solid Interactions and Effects. Division of Organic Plastics and Coatings Chemistry, American Chemical Society, Chicago, Aug 1975. Support from the Ford Motor Company, through a fellowship for M. J. Marmo, is gratefully acknowledged. Support for H. Jinnai from the Maruzen Oil Company is also very much appreciated.
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