Dynamic viscoelastic properties of heat-treated glycerol-impregnated poplar wood

The viscoelastic properties of glycerol-impregnated poplar wood after heat treatments at various temperatures were examined by dynamic-mechanical analysis. The spectra of storage modulus (E′) and loss tangent (tgδ) in the frequency at 10 Hz were measured in the temperature range from −100 to 300 °C. Compared to no peak in E′ spectra and two relaxation processes in tgδ spectra of non-impregnated wood, two peaks in E′ spectra and two new relaxation processes in tgδ spectra were observed in the glycerol-impregnated wood. The magnitudes of the peaks decreased with the heat treatment temperatures. Both the peaks in E′ spectra and the new relaxation processes in tgδ spectra disappeared at the heat treatment temperature above 180 °C. The analysis results suggested that there are special interactions between glycerol and wood polymer and the interactions completed at the higher temperature.