Silvio Manrich

Crystallization behavior of PBT/ABS polymer blends

Poly(butylene terephthalate) (PBT) crystallization behavior is modified by blending it with acrylonitrile-butadiene-styrene copolymers (ABS). The effects of ABS on melting and crystallization of PBT/ABS blends have been examined. Most ABS copolymers of different rubber content and styrene/acrylonitrile ratios studied showed little effect on the melting behavior of PBT crystalline phase. However, ABS copolymer with high acrylonitrile content had a significant effect on the crystallization behavior of the PBT/ABS blends. The nucleation rate of the PBT crystalline phase decreased due to the presence of the high acrylonitrile content ABS, whereas the spherulitic growth rate increased significantly. These phenomena are attributed to changes in nucleation and growth mechanisms of PBT crystalline phase promoted by ABS.

Efeito da Adição de Diferentes Copolímeros em Blendas HDPE/HIPS Pós-Consumo: Morfologia de Fases e Propriedades Térmicas

Blending of post-consumer polyolefins/HIPS has been exploited for obtaining special films with a desired set of properties, which has required studies to understand the behavior of these materials. In this work the effects of commercial multiblock styrene-butadiene (SBS) and linear triblock styrene-(ethylene-co-butylene)-styrene (SEBS) copolymers in blends of post-consumer high density polyethylene (HDPE) and HIPS are reported. Thermal properties and phase morphology were comparatively analyzed for the additives aiming at verifying possible correlations between them. Decreased dimensions of the minor micro phase along with HDPE surface roughness after HIPS selective extraction, independently of the matrix being HIPS or HDPE, showed better effectiveness for SEBS as interfacial tension modifier or as surfactant at the different domains interface when compared with SBS. The results of thermal characterizations, e.g. lower HDPE melting temperature, lower degree of crystallinity, and higher polystyrene glass transition temperature in the presence of SEBS corroborated with this conclusion as it will be discussed further.