THERMAL-DIFFUSIVITY AND CONDUCTIVITY OF PS PPO BLENDS/

A miscible PS/PPO blend was prepared and its miscibility was confirmed by d.s.c. It was found that the miscibility of polymer blends could b e evaluated by the measurement of their thermal diffusivity. The condu ctivity in the liquid state was smaller than that estimated from a lin ear-relation with the PPO content, but in the solid state, the conduct ivity was larger than the estimated value. This phenomenon was conside red to occur because the strong interactions of polymer chains in the solid state increased the density (negative excess volume), resulting in the increase of the thermal conductivity of the blend. Further, all of Filippov, NEL and power law equations were found to be sufficientl y adaptable to the experimentally determined thermal conductivities of PS/PPO blend in the liquid state, but none of them could be adapted t o that in the glass state. (C) 1997 Elsevier Science Ltd.