Thermal behaviour of natural rubber/polystyrene blends: thermogravimetric and differential scanning calorimetric analysis

The thermal behaviour of natural rubber (NR)/polystyrene (PS) blends has been studied by thermogravimetry and differential scanning calorimetry. NR/PS blends are immiscible and incompatible and the compatibility can be improved by the addition of a suitable compatibilizer (NR-g-PS). The effects of the compatibilizer loading and blend ratio on the thermal properties were evaluated. It was found that the weight loss of the blend at any temperature is lower than that of the homopolymers. This suggests that blending improves the overall thermal behaviour of the blend. Addition of the compatibilizer was also found to improve the thermal stability. The initial decomposition temperature increased with the addition of the graft copolymer. The weight loss was found to decrease on the introduction of the compatibilizer. DSC studies revealed that even with the addition of a technological compatibilizer, the NR/PS blends were thermodynamically incompatible. This is evident from the presence of two glass transitions, corresponding to PS and NR phases for the compatibilised and uncompatibilised blends. (C) 1998 Elsevier Science Limited. All rights reserved.