Thermal degradation and ageing behavior of microcomposites of natural rubber,carboxylated styrene butadiene rubber latices,and their blends

The effect of microfillers on the thermal stability of natural rubber (NR), carboxylated styrene butadiene rubber (XSBR) latices, and their 70/30 NR/XSBR blend were studied using thermogravimetric method. Microcomposites of XSBR and their blend were found to be thermally more stable than unfilled samples. The activation energy needed for the degradation of polymer chain was calculated from Coats‐Redfern plot. Activation energy needed for the thermal degradation of filled samples was higher than unfilled system. It indicated the improved thermal stability of the filled samples. The ageing resistance of the micro‐filled samples was evaluated from the mechanical properties of aged samples. The thermal ageing was carried out by keeping the samples in hot air oven for 7 days at 70°C. The mechanical properties such as tensile strength, modulus at 300% elongation, and strain at break were computed. As compared to unfilled samples, micron‐sized fillers reinforced systems exhibited higher ageing resistance. Finally, an investigation was made on the influence of ion‐beam irradiation on microcomposites of NR, XSBR latices, and their 70/30 blend systems using ²⁸Si⁸⁺ performed at 100 MeV. The surface changes of the samples after irradiation were analyzed using X‐ray photoelectron spectroscopy. The results of XPS measurements revealed that the host elements were redistributed without any change in binding energies of C_1s, O_1s, and Si_2p. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007