Study On Flame Retardancy And Sound Insulation Property Of EVA Alternating Multilayered Composites

Sound insulation composites modified with heavy filler have wide application prospect due to its outstanding advantages,such as excellent sound insulation performance,convenience of processing and molding and low cost.However,its high flammability greatly limit the application.In this paper,EVA,a environment-friendly polymer,was used to act as matrix resin of sound insulation composites.The sound insulation properties and flame-retardant properties of the composites were studied respectively.In addition,EVA alternating multilayered composites consisting of flame-retardant layer and sound insulation layer were prepared through a layer-multiplying coextrusion technology.The main work and research results of this paper are as follows:First,the sound insulation properties of the EVA composites,which was filled with BaSO₄,mica powder and hollow glass microsphere respectively,were investigated by impedance tube measuring system.The results revealed that EVA/BaSO₄ composites exhibited the best excellent sound insulation properties,which were improved with the increase of the amount of BaSO₄.Second,the flame retardancy of the EVA composites modified with different flame retardants?Aluminum hydroxide,Aluminum hypophosphite,and intumescent flame retardant?were investigated by limited oxygen index test?LOI?,vertical burning test?UL-94?and cone calorimeter test.The results revealed that IFR/EVA composites exhibited the best excellent flame retardany: when the content of IFR was 40 wt%,the LOI value of IFR/EVA composite was 43,and a V-0 classification could be achieved.In addition,the flame-retardant mechanism of IFR was analyzed by means of the experimental and the theoretical TG curves of CA/APP?3:1 in weight?and char-forming ability of CA?APP and IFR.Third,the EVA/IFR/BaSO₄ composites were prepared by melt-blending method.The flame retardancy of the composites were investigated by limited oxygen index test,vertical burning test and cone calorimeter test.The results revealed that the flame-retardant properties of the composites were decreased due to the heavy filler,which decreasedthe content of the IFR in the composites and decreased the quality of the char layer formed in combustion.Fourth,EVA alternating multilayered composites,consisting of flame-retardant layer modified with IFR and sound insulation layer modified with BaSO₄,were prepared through a layer-multiplying coextrusion technology.The flame retardant properties and the sound insulation properties of the composites were investigated by limited oxygen index test,vertical burning test,cone calorimeter test and impedance tube measuring system.The results revealed that the alternating multilayered structure had a positive effect on the improvement of the flame retardancy and sound insulation properties compared to the contrast sample which was prepared through blending;With the increase of the number of the layers,the flame retardancy of the multilayered composites decreased after the first increase,;and the multilayered composites with 8 layers had the best flame retardancy.The results of impedance tube measuring system showed that the sound insulation properties of the multilayered composites were improve with the increase of the number of the layers.