Effect of different copolymers (hydrogenated and non-hydrogenated, with different molecular weights and different content of styrene) in the compatibilization of PS + PP (80+20) polyblend

Abstract

We have studied the effect of the addition of different compositions of several styrene / butadiene / styrene (SBS) triblock copolymers, hydrogenated and non-hydrogenated, with different molecular weights and different content of styrene, on the PS + PP (80+20) polyblend. We have determined the influence of these parameters on thermal and mechanical properties as well as on the observed morphology. As the composition of the hydrogenated copolymer or the copolymer with a similar content of styrene and butadiene was increased, the dispersion of particles increased, lowering remarkably their size and producing this way a better interfacial adhesion in the blend. Excluding the copolymer with similar content of styrene and butadiene in its structure, the rest of the copolymers show a strong tendency to form micelles or mesophases in the matrix as the amount of copolymer increases, improving some mechanical properties such as impact strength but deteriorating others like the yield and break stresses. On the other hand, the presence of compatibilizers, at any composition, does not have any effect on the thermal parameters of the blend. Nevertheless, the presence of PS, amorphous and the majority component in the blend, affects the crystallization process of PP, enhancing in a wide temperature range (from 125 °C to 40 °C) its crystallization process.