Mechanical, thermal and morphological properties of water-crosslinked wood flour reinforced linear low-density polyethylene composites

Wood flour (WF) reinforced linear low-density polyethylene (LLDPE) composites were prepared. Water-crosslinking technique was used to improve the physical properties of wood composite. Composites were compounded in a twin-screw extruder and treated with a coupling agent (vinyltrimethoxysilane, VTMOS), and then moisture-crosslinked in hot water. Composite after water-crosslinking treatment exhibited better mechanical properties than the non-crosslinked one because of the improved chemical bonding between the wood fiber and the polyolefin matrix. As the wood flour content reaches to 30 wt% and after water-crosslinking for 4 h, tensile strength and flexural strength are increased by 87% (14.7–27.5 MPa) and 137.5% (11.2–26.6 MPa) with respect to that of non-crosslinked ones. Scanning electron microscopy (SEM) of the fracture surfaces of water-crosslinked composites showed superior interfacial strength between the wood fiber and the polyolefin matrix. Thermal analyses of water-crosslinked composites indicate that thermal degradation temperature and heat deflection temperature of composite increase with the increasing water-crosslinking time. The heat deflection temperature of the composite can be raised from 55.7 to 88.5 °C.