Study On Flame Retardant And Smoke Suppression Wood Flour/polyvinyl Chloride Composites With Zinc Borophosphate Ammonium

In this study,the zinc borophosphate ammonium compounds(ZBPs)were synthesized by ionothermal,hydrothermal and boric acid ’flux’ method.The structure,morphology and composition of the sample were characterized by XRD,SEM,XPS,FTIR and TGA analyses.The synthesized ZBPs were added as a flame retardant to wood flour/polyvinyl chloride composites(WF/PVC)during extrusion molding and hot pressing process.Thermogravimetric analysis(TG)and cone calorimetry(CONE)of the resulting WF/PVC were carried out to reveal the pyrolysis and combustion properties.The incorporating effect of the ZBPs on the mechanical properties of the composites were tested by universal mechanical testing machine and combined impact tester.The main results are given as below:(1)The flame-retardants ZBP-A and ZBP-B were synthesized by hydrothermal method and boric acid ’flux’ method.The crystal morphology of ZBP-A was mainly hexagonal prisms with small particle size.ZBP-B was mainly orthorhombic.Both contain flame retardant elements oflN,P,B,and Zn.Incorporation of ZBP-A and ZBP-B in the WF/PVC composites resulted in an improved thermal stability and increased residual charcoal.The addition of ZBP-A and ZBP-B had little effect on the heat release of the composites,but significantly reduced the smoke release rate of the materials.In general,both ZBP-A and ZBP-B imparted the WF/PVC composites with a certain flame retardance and smoke suppression ability.(2)The effects of ZBP-B addition on the pyrolysis,flame retardancy,and mechanical properties of composites were investigated systematically.The optimum content of ZBP-B in WF/PVC was among 10%-15%.(3)A flame retardant ZBP-C was synthesized by ionothermal synthesis using 1-ethyl-3-methyl imidazole chloride as solvent and template.The compound exhibited high crystallinity and cubic structure measuring about 5 μm.The ZBP-C was incorporated in WF/PVC by extrusion process.TG results showed that addition of ZBP-C caused a lower initial thermal decomposition temperature and a higher residual charcoal.CONE test showed that addition of ZBP-C substantially reduced the thermal release of materials,but had little effect on the smoke release.