Effect of biomass source on the physico-mechanical properties of polyurethane foam produced by microwave-assisted liquefaction

Different biomass sources (bamboo, rape straw, lignin, and Yaupon holly) were liquefied using microwave energy to produce biopolyols, which were then used to prepare biofoams without any further separation process. The results indicated that the content of hydroxyl groups in biopolyols derived from different biomass sources was sorted in descending order as rape straw, Yaupon holly, bamboo, and lignin. The rheological analysis demonstrated that the biopolyols were pseudoplastic, and the yield stress of biopolyols was remarkably increased with increasing biomass content. The compressive strength of polyurethane (PU) foam was rendered smaller by introducing biomass sources. Nevertheless, the biofoam obtained from biomass sources with higher hydroxyl groups content had better PU performance. In addition, the termite resistance performance of PU foam increased with the introduction of Yaupon holly, rape straw, and bamboo sources. Accordingly, the biofoams derived from the liquefaction of rape straw performed better than those from other biomass sources.