Thermal Softening Properties of Torrefied Wood Powder as a Raw Material for Production of Biomass-based Plastics

摘要

It is expected that conventional petroleum-based plastic will be replaced with biomass-based plastic to solve the issues of the global environment. To provide the dimensional stability of biomass-based plastics, the torrefaction treatment is conducted to reform the hydrophile property of woody biomass. There are two objectives of the study. One is to investigate the effect of torrefaction on thermal softening properties of wood powder. The other is to clarify the optimum mass yield conditions which simultaneously satisfy both water resistance and bending strength of extruded wood molding. The following results are obtained: (1) As the mass yield decreases, the softening temperature increases, which is related to the thermal decomposition of hemicellulose contained in woody biomass. (2) The torrefied wood powder has the non-Newtonian flow property of pseudo-plastic fluid. The mass yield has a large effect on apparent viscosity especially at low temperature conditions. (3) The decrease in the mass yield improves the hydrophobic property, but reduces the bending strength of extruded wood molding. From the result of the trade-off relationship between hydrophobic property and bending strength against mass yield, it is found that the optimum mass yield is around 0.9.