Enhancing the flame retardancy and mechanical properties of veneered wood flour/polyvinyl chloride composites

A wood flour/polyvinyl chloride (WF/PVC) composite with poplar veneer as the surface layer (veneered WF/PVC composites) was prepared by hot pressing. To improve the flame retardancy of the veneered WF/PVC composites, a self-developed flame retardant of wood (FRW, composed of guanylurea phosphate [GPU], boric acid and few additives) was impregnated in the poplar veneer, and zinc oxide (ZnO) was incorporated into the WF/PVC composites. Properties of the composites, including thermal decomposition, flame retardancy, interface adhension strength, impact strength and flexural properties, were investigated. Thermogravimetric analysis (TGA) showed that the FRW and ZnO accelerated the pyrolysis of the composites in the first stage and had a positive effect on thermal performance at high temperature. Cone calorimetry showed that the FRW and ZnO promoted the rapid formation of carbon and had a positive effect on the flame retardancy and smoke inhibition properties. The mechanical results showed that a strong interface adhension strength was formed between the surface poplar veneer and PVC composite board substrates. The poplar veneer significantly improved the impact and flexural properties of the WF/PVC composites.