Thermal conductivity of wood-plastic composites as insulation panels: theoretical and experimental analysis

The aim of this study is evaluating the thermal performance of wood plastic composites (WPCs) as insulation panels depending on the values of thermal conductivity (k). Three types of wood flour taken from (pine, oak and walnut) trees with concentrations (10, 20, 30 %), and two types of thermoplastics; high density polyethylene (HDPE) and polypropylene (PP), have been selected for the evaluation. Theoretical work uses mathematical relations in the calculation of thermal conductivity of WPCs. Experimental work includes the manufacturing of the specimens, the measurements of k-values. The results show that the increasing in wood content leads to a reduction in k-values for WPCs by 6-8.5% for each 10% addition of wood. The k-values of WPCs tend to increase, when temperatures rise from 25-75 oC, by 20-25% for HDPE-wood composites, and by 15-20% for PP-wood composites. Furthermore, 10 % of water content will increase the k-value by 10-20%.