Plastomers

Plastomers. The production of resins (polyfvinyl chloride], polystyrene, and poly [styrene-co-acrylonitrile]) with relatively high toughness has been one of the most important aims of industry. This can be achieved by modifying a rigid chain with small amounts of elastomers. The best results have been obtained by the use of block and graft copolymers. 

Berlin and coworkers (5,56) desired to obtain a material with an increased mechanical strength. They carried out a plasticization of bulk ami emulsion polystyrene molecular weight 80000 and 200000 respectively at 150-160° C, with polyisobutylene, butyl rubber, polychloroprene, polybutadiene, styrene rubber (SKS-30) and nitrile rubber (SKN 18 and SKN 40). The best results were obtained with the blends polystyrene-styrene rubber and polystyrene-nitrile rubber. An increase of rubber content above 20-25% was not useful, as the strength properties were lowered. An increase in the content of the polar comonomer, acrylonitrile, prevents the reaction with polystyrene and decreases the probability of macroradical combination. This feature lowers the strength, see Fig. 14. It was also observed that certain dyes acts as macroradical acceptors, due to the mobile atoms of hydrogen of halogens in the dye, AX  

Thus in coloring polymers by mastication it should be considered that dyes of different classes, even in small amounts, may affect the material properties, see Table 11. 

The possibility of increasing poly(vinyl chloride) toughness has been investigated by many workers (52,57-59). The effect of modification depends markedly on the compatibility of the initial substances, their polarity, and structure. 

Poly(vinyl chloride) was also masticated with neoprene in an inert atmosphere at 145° C for 30 min (60), giving an easily flowing powder of low bulk density. Goto and coworkers (61) blended poly(vinyl chloride), poly(methyl methacrylate) and polystyrene in an open roll after investigating the degradation condition for each component to find the optimum combination of the component. 

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NBRin pLASTOMERS, SYNTHETIC - NITRILE RUBBER] (Vol 8) -cis-l,4-polyisoprene in pLASTOMERS SYNTHETIC - POLYISOPRENE] (Vol 9)... 

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