Influence of eco-friendly pretreatment of lignocellulosic biomass using ionic liquids on the interface adhesion and characteristics of polymer composite boards

Abstract

In this investigation, the effect of ionic liquids (ILs) pretreatment on the interfacial behavior, physical, and thermal properties of compression-molded composite boards produced from wood flour and high-density polyethylene was studied. Firstly, wood flour was pretreated with with two types of synthesized ILs, namely 1-(3-trimethoxysilylpropyl)-3-methylimidazolium chloride (IL-Cl) and 1-(3-trimethoxysilylpropyl)-3-methylimidazolium thiocyanate (IL-SCN). Thereafter, the interfacial strength, weight loss, water absorption, and thickness swelling of the specimens prepared from untreated and ILs-treated were evaluated. Further, the chemical treatment of wood flour with ILs was tracked by Fourier transform infrared spectroscopy. The morphological aspects of the specimens were characterized using Field Emission Scanning Electron Microscope (FESEM). Results demonstrated that the strong interaction between the wood flour and high-density polyethylene occurred in the presence of ILs pretreatment, which corresponded with the minimum amounts of adhesion factor. The tan δ peak was shifted to higher temperature for the modified samples than unmodified ones. It was noted that thermal stability of the composite boards improved as a result of ILs pretreatment. The residual weight in temperature of 600℃ was increased to 21.09% and 17.28% for the composite panels made from IL-SCN- and IL-Cl-treated wood, respectively, as compared to a residual mass of 16.35% for the composite based on untreated wood. Furthermore, physical testing revealed that the specimens produced from ILs-treated wood exhibited superior water resistance and dimensional stability compared to that of untreated ones.