Natural rubber to replace acrylonitrile butadiene styrene in polycarbonate blends and composites

Abstract

In the challenging prospect of developing “green” materials, the present research studied the possibility to replace acrylonitrile butadiene styrene (ABS) which is a petroleum based, synthetic rubber in polycarbonate (PC) blends with natural rubber (NR) for thermoplastic elastomers (TPEs) applications. An acrylic based impact modifier and talc were included in order to investigate the correlation between phase morphology and mechanical and thermal properties of the blends and composites. A simple technique of two roll mills were performed to obtain the blend and composite pellets which later on were processed into test specimens using an injection molding technique. As NR is outstanding in terms of toughness, when blending with PC a significant improvement of Izod impact strength was advantageous even with a low amount of NR at 5% w/w. In opposite, the drawback of NR incorporated PC was   a drastic reduction in ductility which was shown by 75% decrease in the percent elongation to break. As the NR contents increased, the phase heterogeneity was more pronounced and resulted in lowering most properties.  However, a better homogeneity of the blend using an impact modifier did not show any property enhancement besides the impact strength.  Scanning electron microscopy (SEM) study suggested that talc was more miscible in NR than in PC and hence tended to improve properties when added into a blend with   a high NR content. With an inadequate NR amount, talc dispersed in the polymer matrix and only elastic modulus and Vicat softening point were enhanced due to the stiffness and heat resistant properties of talc. Mechanical and thermal properties, in general, of the PC/NR/talc and PC/ABS/talc were comparable, suggesting the possibility to replace ABS with NR. In addition, the reproducibility of the tests was observed, implying the efficiency of the two roll mills technique for blend and composite preparation.