Investigation of bio-composites using Novolac type liquefied wood resin: effects of liquefaction and fabrication conditions
Wood liquefaction using an organic solvent and an acid catalyst has long been studied as a novel technique to utilize biomass as an alternative to petroleum-based products. Oxalic acid is a weaker organic acid than a mineral acid and wood liquefaction with oxalic acid as a catalyst will result in a higher amount of wood residue than that with a mineral acid. Yet the wood residue can be used as a filler in the bio-composite fabrication. In this study, bio-composites were fabricated from wood flour and novolac type liquefied wood resins with wood residue. The effects of liquefaction temperature, reactor type, hot press temperature, and press time on the mechanical and physical properties of the composites were investigated. The composites with the liquefied wood resin from the sealed Parr reactor yielded higher thickness swelling than those with the liquefied wood resin from the three neck flask likely due to the hydrophilic wood components incorporated in it and the lower cross-link density than the liquefied wood resin from the three neck flask during the resin cure process. Both hot press temperature and press time had significant effects on the mechanical and physical properties of the composites. The results of dimensional stability tests implied that the matrix resin didn’t cure well at the hot press temperature 155°C.