Interface Bonding Properties and Mechanism of Poplar Board-Veneered Wood Fiber/Polypropylene Composites with Chlorinated Polypropylene Films as an Intermediate Layer

It is difficult to decorate wood plastic composites with wood veneer because their surface energy is low and there are no pores on the surface. In the present study, we developed an environmentally friendly and convenient method to decorate the wood fiber/polypropylene (WF/PP) composite board. We used chlorinated polypropylene (CPP) as an intermediate film to laminate wood veneer to WF/PP composite boards by hot-pressing at 110 degrees C and then cooling down. The interface bonding mechanism between the wood veneer, CPP layer, and WF/PP composite was analyzed using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), surface roughness test, and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The results indicated that CPP penetrated the wood pores and formed a firm anchor structure. SEM images showed small cracks at the interface between CPP and PP when WF/PP contained less WF. The results of SEM-EDS and ATR-FTIR showed that WF/PP composites with a higher WF content would have more fibers exposed at the surface, thus making the surface rough and providing more specific surface area. The veneered WF/PP composite with 80% WF content had the highest surface bond strength and water resistance.