Preparação da mistura poliestireno/borracha natural através da incorporação do látex de borracha natural durante a reação de polimerização em emulsão do estireno

Abstract

This dissertation aimed to develop a new methodology for the preparation of the blend between polystyrene and natural rubber (PS / NR) in order to avoid the presence of crosslinking in natural rubber in order to solve problems previously encountered by the research group. The strategy of this process was based on the polymerization in emulsified system of the styrene monomer and the incorporation of the natural rubber during the polymerization process, obtaining a material characteristic of a thermoplastic elastomer (TPE). In this process, the potassium persulphate was used as a polymerization initiator in order to avoid crosslinking or graphitization of the material. In this study, mixtures between PS / NR containing different amounts of natural rubber were prepared. In addition, mechanical blends of PS / NR containing the synthesized mixture were prepared. The synthesized PS / NR blends were characterized by infrared spectroscopy (FTIR) and Proton nuclear magnetic resonance (1H NMR). The results indicated the presence of both polymers in the blend. The rheological analyzes of the solutions containing the synthesized mixtures showed that the materials have very similar behavior to the mixtures prepared by mechanical mixer. The study of the blending processing showed that the addition of 5 wt% PS / NR (synthesized) reduces the processing energy, improving processability of the blend. The morphological analysis performed by scanning electron microscopy (SEM) revealed the presence of a characteristic morphology of a dispersed mixture. The thermogravimetric analyzes of the blends showed that the addition of 5% wt of the PS / NR blend improves the thermal resistance of the material at elevated temperatures.