| Abstract: | Two polymers being generally incompatible, it was interesting to examine if compatibility of two homopolymers can be realized by addition of a corresponding: graft, block, or random copolymer. Our study was limited to two systems of atactic polymers: polystyrene-polymethacrylate and polystyrene-1,4 cis polyisopren, mainly because no crystallisation is observed in this case at common temperatures. For mixtures of copolymers and homopolymers in the solid state, it is possible by examination of films, obtained by solution evaporation, to determine the limits of the compatibility region and the most important corresponding parameters, that is composition of the mixture, molecular weight, and structure of the copolymer. Ternary diagrams, for mixtures of two homopolymers and a copolymer, show that only block copolymers are able to achieve better compatibility, especially if their composition is near 50:50 and if molecular weight of the homopolymers is lower than those of block copolymers. Graft and random copolymers however have practically less or no effect on compatibility. Further for the system polystyrene–polyisopren and the corresponding block-copolymer, the relation between compatibility and shock resistance has been shown. |
