Thermophysical properties of wood-polymer composites

Theoretical models are proposed for predicting the longitudinal and transverse thermal conductivities of wood-polymer composites. The predictions of the models are in good agreement with the measured thermal conductivities of red maple boards impregnated with either polystyrene, polymethyl methacrylate or polyfurfuryl alcohol. The density, heat capacity, transverse thermal conductivity and longitudinal thermal conductivity of the red maple boards were 589 kg/m3,1290 J/kg K, 0.155 W/mK and 0.358 W/mK, respectively. Polymer impregnation moderately altered the thermophysical properties of the boards. The increase in density of the boards ranged from 60% to 79%, the increase in transverse thermal conductivity ranged from 12% to 33%, the increase in longitudinal thermal conductivity ranged from 3% to 13% and the decrease in heat capacity ranged from 3% to 11%. Polystyrene provided the largest increase in density whereas polymethyl methacrylate yielded the greatest increase in thermal conductivity and the largest decrease in heat capacity. Treatment with polyfurfuryl alcohol caused the samples to swell and resulted in the lowest increases in thermal conductivity and density. On average the thermal diffusivity of the composites was 26% smaller than that of the parent wood.