ABSTRACT:The morphology, rheological and tensile properties of polyamide 6 (PA6)/poIy(styrene-co-acrylic acid) (SAA) blends were examined as a function of the acrylic acid (AA) content in SAA. It was found that the AA unit in copolymers has a pronounced effect upon the morphology of the blends. The dispersed phase size was significantly reduced with increasing AA content in SAA. A reduction in the particle size of the dispersed phase resulted in improvement in tensile properties of the blends.KEY WORDS Morphology / Rheological Properties / Tensile Properties / Polyamide 6 / Poly(styrene-co-acrylic acid) / Domain Size / Chemical Reaction / Long Branching / Polystyrene (PS) and polyamide 6 (P A6) are two important classes of polymers. PS is widely used as an injection molding and vacuum forming material due to low cost, good mold ability, low moisture absorption, good dimensional stability, good electrical insulation properties, and colorability. The principal limitations of PS, however, are its brittleness, inability to withstand the temperature of boiling water and mediocre oil resistance. PA6 is an engineering thermoplastic material. It finds many applications in eletrical, mechanical, and automotive parts due to its very high strength, wear and heat resistance, ease of fabrication, and excellent barrier properties to oils. However, it has not become a commodity plastic material because of its relatively high cost. Therefore it is desirable to compromise properties and cost by blending PS and PA6.It is often difficult to obtain good dispersion in polymer blends whose components are essentially insoluble in each other, particularly for blends of a polar polymer such as P A6 with a nonpolar polymer such as PS. Several authors l -9 have reported that the presence of a block or graft copolymer of appropriate chemical structure provides lowering of the interfacial energy and an improvement of the interfacial adhesion between the two phases. The final morphological effect is reduction in particle size of the dispersed phase in the blend. For example, in the case of polystyrene (PS)/polyethylene (PE) blends, Heikens et al. 7 observed that the dimensions of the PE domains decreased with the addition of PSco-PE graft and block coplymers. Recently attempts were made to compatibilize immiscible polymer pairs by introducing a specific interaction between constituents of individual polymer chains. It has been reported that copolymers of methyl methacrylate and 4-vinylpyridine were miscible poly(butyl acrylate-eo-acrylic acid) through specific interaction.loIn this work, acrylic acid (AA) was introduced into PS to enhance the compatibility of PA6 and PS blend, and the morphology, rheological and tensile properties of P A6/SAA blends were examined as 1023

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The phase behavior of binary blends of vinyl chloride-vinyl acetate copolymers with two polymethacrylates, poly(methyl methacrylate) (PMMA) and poly(n-butyl methacrylate) (PnBMA), has been examined as a function of the vinyl acetate (VAc) content in the copolymer. From the variation of cloud points with the copolymer composition, segmental contact energy parameters X¡¡s for various monomeric unit pairs have been estimated by using a copolymer model based on Patterson's equation of state theory. It has been found that the segmental interaction of vinyl acetate with methyl methacrylate and vinyl chloride is attractive in each case, indicating that poly(vinyl acetate) is miscible with PMMA and poly(vinyl chloride) (PVC). The incorporation of the VAc unit into PVC did not raise the cloud points of PMMA/PVC and PnBMA/PVC blends. The effect of the VAc unit on the phase behavior of both blends was analyzed according to the copolymer model based on Patterson's theory.

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