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Abstract: The thermal stability of natural rubber (NR) and carboxylated styrene butadiene rubber (XSBR) latices and their blends was studied by thermogravimetric methods. Ageing characteristics of these latex blends were studied by applying hot air oven thermal ageing for seven days at 70°C. The mechanical properties of the aged samples were studied. Thermal degradation and ageing properties of these individual latices and their blends were investigated with special reference to blend ratio and vulcanization techniques. As the XSBR content in the blends increased their thermal stability was also found to increase. Among sulphur and radiation-vulcanized samples, radiation cured possesses higher thermal stability due to the higher thermal stability of carbon–carbon crosslinks. DTG curves were used for the determination of different stages involved in the degradation. Activation energy for degradation was determined from Coats–Redfern plot. The properties of aged samples were found to decrease due to chain depletion. However, the moduli of XSBR and NR/XSBR blends were found to increase owing to the formation of crosslinks upon ageing. [Copyright &y& Elsevier]

A series of interpenetrating polymer network membranes have been synthesised from natural rubber and polystyrene by the sequential polymerisation technique. The transport of aromatic hydrocarbons through semi- and full-interpenetrating polymer network membranes (IPNs) have been studied in detail by tracing the solvent uptake up to equilibrium. The sorption was carried out in a series of aromatic solvents viz. benzene, toluene and xylene. The effect of temperature on swelling is studied by carrying out the experiments in toluene in the temperature range of 30–75 °C. The effects of blend ratio, crosslinker content and nature of initiator on the diffusion of various solvents were analysed. It was found that in all cases, the uptake value increased by about 50% as the PS content decreased from 70–30%. The diffusion, sorption and permeation coefficients were evaluated. As the crosslink density was increased, the uptake decreased by 40%. Kinetic and thermodynamic parameters were evaluated from diffusion experiments. The diffusion profiles were compared with theoretical predictions. The influence of swelling on the mechanical performance of the membranes has been investigated by conducting tensile testing of swollen specimens. [Copyright &y& Elsevier]