Mechanical and Physical Properties of Wood–Plastic Composites Containing Cellulose Nanofibers Added to Wood Flour

Abstract

Abstract Recently, the usage of wood–plastic composite (WPC) products has increased, mainly for exterior decking. The shape of fillers is one of the important factors deciding the mechanical and physical properties of WPCs. Surface-fibrillated wood flour (WF) improves the mechanical properties of WPCs, although it requires a lot of energy and time to produce the fibrous structure during the pulverization process. Therefore, the adsorptive interaction between cellulose nanofiber (CNF) and WF by hydrogen bonding was investigated. We considered that CNF could form the fibrous structures on the WF surface by mixing CNF and WF. Also, it is thought that the addition of CNF could increase mechanical and physical properties of WPC because CNF has better physical and mechanical properties than most other fibers. The objective of this study was to produce WF-CNF fillers and to evaluate the mechanical and physical properties of WPCs containing WF-CNF fillers. WF-CNF fillers could be produced by freeze-drying after mixing WF, CNF, and water. The fibrous structures on the WF surface were observed through scanning electron microscope images of WF-CNF filler containing 3 weight percent CNF. A WPC with WF-CNF filler containing 22 percent (by weight) WF and 3 percent (by weight) CNF showed improved mechanical properties compared with WPCs without CNF. The water absorption of WPCs containing CNF was found to decrease with increasing CNF content.