The Influence Of Different Flame Retardancy On The Properties Of Wheat Straw Fiber/Recycled Polypropylene Composite

As a new kind of green material, plant fiber/plastic composite materials are used more and more widely, due to its flammability, the studies of its flame-retardant is very urgent. Halogen flame retardant was the mainstream flame retardant. However, they seriously do harm to the environment and is eliminated gradually. Whereas, inorganic flame retardant which does little harm to environment plays an important role, at the same time, intumescent flame retardant, which effectively overcome the shortcomings of halogen flame retardant, has aroused widely concern.To promote the application of wheat straw fiber/recycled PP composites, the issue investigated the influence of different flame retardant (such as Al(OH)₃, Mg(OH) 2, APP, PER, MEL) on the properties of wheat straw fiber/recycled PP composites. According to general plan, the processing parameters were investigated firstly, and samples were made at a variety of ratio of different flame retardant through extrusion, pelleting and injection molding. Through the limited oxygen index test, vertical combustion test, thermal degradation test, mechanical properties test, and by observing the micro-structure, the theory about the influence on the properties of composites caused by flame retardant was studied. It is indicated that the adding of flame retardant improved the flame retardancy of composite significantly; The tensile strength, bending strength and impact strength were increased at first while decreased later as the content of flame retardant continued to rise; When Al(OH)₃ and Mg(OH) 2 were compounded, the flame retardancy of composite was much better than that when added separately; When PP:Al(OH)₃:Mg(OH) 2=13:52:17.5:17.5, the composite has a good performance of both flame retardancy as well as mechanical properties(At this point, the LOI is 28.2, and the result of vertical burning become to FV-1; tensile strength, bending strength and impact strength respectively rouse up to 31.32MPa, 35.97MPa, 8.92KJ/m²); When APP:PER=2:1, and content of IFR is 25%, the composite has a fine integrated properties(the LOI is 26.7, the rate of the vertical combustion test is FV-1, the tensile strength, flexural strength and impact strength increased to 32.8MPa, 45.7MPa and 8.79KJ/m² respectively); The mechanism of the influence on the mechanical properties of composites caused by flame retardant was studied through further analysis by observing the micro-fracture; The thermogravimetric analysis also indicated that the adding of flame retardant hindered and delayed the thermal degradation process of composite effectively. Those research findings have important theoretical and practical value for the application of wheat straw fiber/recycled PP composites.