Mechanical and thermal properties of impact modified PBT blends and impact modified PBT nanocomposites

Abstract

Abstract Elastomer toughened poly(butylene terephthalate) (PBT)/organoclay [Cloisite 30B, organo-montmorillonite (OMMT)] nanocomposites were prepared via melt blending using a micro-compounder. In this work, two types of impact modifiers, ultra low density polyethylene grafted glycidyl methacrylate (ULDPE-g-GMA, IM1) and ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA, IM2) were used, and a detailed comparison of the effect of both was made. With respect to the impact strength, 2 wt% of ULDPE-g-GMA produced a better result as compared to 2 wt% E-MA-GMA. Therefore, 2 wt% of ULDPE-g-GMA is considered as the optimized percentage for the preparation of nanocomposites. Being an impact modifier, ULDPE-g-GMA decreases the yield stress, tensile modulus and breaking strength of pure PBT. This issue was addressed in this paper by using organoclay, which may improve the tensile properties of PBT materials. The content of ULDPE-g-GMA was kept constant, whereas organoclay (OMMT) content was varied from 2 to 5 wt% in nanocomposites. The melting and crystallization behavior of pure PBT, impact modified PBT and its nanocomposites were studied by differential scanning calorimetry (DSC). Crystalline morphology was investigated using polarizing optical microscopy (POM) at 185°C, 195°C, and 205°C crystallization temperatures. The optimum increase in tensile modulus of the elastomer toughened PBT nanocomposites was seen with a 3 wt% addition of organoclay.