Investigation Of Interfacial Modification And Flame Retardancy Of Wood Fiber Reinforced Linear Low Density Polyethylene Composite

Wood fiber reinforced plastic composites are a new kind of materials which have attracted much research interest. The mechanical property, flame tetardancy and thermal degradation of wood fiber/linear low density polyethylene composite (WF/LLDPE) were investigated in this thesis. Experimental data were obtained by means of all kinds of instruments such as a tensile machine, an Izod impact test machine, thermogravimetric analysis, limit oxygen index(LOI) instrument and so on. The results showed that the newly synthetic alkyl phosphates, silane coupling agents, polyvinyl alcohol and styrene-acrylic acid copolymer were all used as compatibilizers, which could slightly improve the mechanical properties of composite. Compared with these compatibilizers, it was found that polyethylene grafted maleic anhydride(MAPE) had a good compatibility between LLDPE and woodfiber and could obviously improve the tensile strength and impact strength of the composite. Especially, the tensile strength was improved greatly. The addition of flame-retardant agents deteriorated the mechanical properties with the increase of limit oxygen index of composite. Ammonium polyphosphate (APP) and the mixtures of APP, melamine phosphate (MP) or pentaerythritol (PER) were used as flame retardants. Ammonium polyphosphate(APP) is one of the most appropriate flame-retardant agents, because it could provide the higher LOI and had the less effect on the mechanical strength of material. Whereas PER could clearly decrease both tensile strength and Izod impact of WF/LLDPE composite, Because PER involved in the esterification reactions between wood fiber and MAPE. It was also found that wood fiber obviously influenced the thermal degradation behaviour of LLDPE. Wood fiber made the rapid thermal degradation of LLDPE take place earlier. The thermal degradation behaviour of wood fiber pretreated by the compatibilizers was discussed, it was testified that the compatibilizers could contribute to the char formation.