Oil palm trunk powder blended with citric acid directly used as wood adhesive by one step liquefaction reaction

Abstract

The use of lignocellulosic raw materials to synthesize bio-adhesives through liquefaction is growing. To add value to oil palm trunk agricultural waste, this study aimed to investigate the ability to bond rubberwood veneer with powdered oil palm trunk, with or without citric acid by one-step liquefaction during hot pressing. The results revealed that the oil palm trunk powder acts as a great binder of rubberwood veneer when compressed at a medium temperature (180 °C) for 5 min. The dry shear strength was not significantly affected by the amount of citric acid when compared to control specimens bonded with only oil palm trunk powder. The acidity of oil palm powder increased with the citric acid dose. The citric acid functions as a cross-linking agent and catalyst improving water resistance, especially in acidic conditions by generating furan products that were confirmed with FTIR. It should be noted that a high dose of citric could degrade the carbohydrate polymers and reduce the lifetime of the wood product.