Temperature Dependence of Effective Thermal Conductivity and Thermal Diffusivity of Treated and Untreated Polymer Composites

Thermal properties, such as thermal conduc- tivity, thermal diffusivity, and specific heat, of treated and untreated oil palm fiber-reinforced PF composites were measured simultaneously at room temperature and normal pressure using the transient plane source (TPS) technique. An increase in thermal conductivity was observed in the fiber-treated and resin-treated composites. Surface modifi- cations of fibers by prealkali, potassium permanganate, and peroxide treatments increased the fiber-matrix adhesion by increasing porosity and pore size of the fiber surfaces. The increase in crosslinking enhanced the thermal conductivity of a composite of resin treated with peroxide compared to other composites. Also an attempt was made to explain the temperature dependence of thermal conductivity and ther- mal diffusivity of amorphous polymer samples using the same technique. It was observed that at the glass-transition peak of the polymer, thermal conductivity and diffusivity were maximum. Below and above this temperature their values decreased. This has been explained on the basis of predominant scattering processes. An empirical relationship was established for the theoretical prediction of thermal conductivity and diffusivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1708 -1714, 2003