Thermal conductivity of styrene butadiene rubber compounds with natural rubber prophylactics waste as filler

Efforts on a large scale have been made by the polymer industry to develop cost effective techniques to convert waste and used rubber into processable forms. Some of the authors have developed a cost effective technique for the reuse of natural rubber (NR) latex condom waste as a potential filler in styrene butadine rubber (SBR). It has been proved that waste NR particles do reinforce SBR matrix. For optimizing cryosystem performance of the blends, characterization of the composites in terms of thermal behaviour is important. Thermal conductivity of SBR filled with lightly cross-linked NR latex waste is measured using the transient plane source (TPS) method in the temperature range of 100-300 K, It has been found that the thermal conductivity of SBR composites increases linearly with temperature to a peak value at a temperature which lies well within the glass transition region of SBR. With further increase of temperature the thermal conductivity decreases asymptotically to a constant value near 300 K. The variation in the thermal conductivity is empirically correlated with the present experimental data by the equation, lambda(T) = a + bT + cT(2), where a, b and c are parameters which are polymer dependent and have different values below and above the glass transition. The observed variation in thermal conductivity is explained on the basis of various phonon scattering mechanisms, namely structure scattering and cooperative motion of repeat units, as also by considering structural features and the effect of temperature on structural units in a phenomenological manner. (C) 1999 Elsevier Science Ltd. All rights reserved.