Hydrophobic wood flour derived from a novel p-TsOH treatment for improving interfacial compatibility of wood/HDPE composites

The interfacial compatibility between wood and polymers of wood/plastic composite (WPC) has been widely investigated. However, the reported methods for improvement of interfacial compatibility almost utilized the compatibilizer. In this work, a compatibilizer-free method was applied to enhance the interfacial compatibility between wood flour (WF) and high-density polyethylene (HDPE). p-toluenesulfonic acid (p-TsOH) was used to selectively remove hemicelulose, which would significantly improve the hydrophobicity of WF. It was found that most hemicellulose (about 91%) and a small amount of lignin were solubilized from WF. The static water contact angle (WCA) of WF sheet was significantly increased from nearly 0° to 135.7°, indicating that the WF was converted from hydrophilic to hydrophobic. Scanning electron microscope (SEM) showed p-TsOH treatment of WF could effectively improve the interfacial bonding between the WF and HDPE. The composite with 50 wt% modified-WF (MWF) showed optimum mechanical properties with an increase of 33.5% and 38.7% in tensile strength and flexural strength, respectively, as compared to those of corresponding WF/HDPE composite.