Performance Evaluation Of Ethylene Vinyl Acetate Composites Modified By Basalt Fiber And Magnesium Hydroxide

The rapid development of polymer materials made it widely used in people’s daily life.Ethylene-vinyl acetate（EVA）,as a commonly used polymer material,according to the content of vinyl acetate in EVA,it was widely used in various industries.However,EVA resin was a flammable material,and there was a huge fire hazard during use.Therefore,it was necessary to add flame retardants to improve its flame retardant performance,but this usually lead to a mechanical properties decreasing of the composites.In order to solve the problem,reinforcing materials or surface modification of flame retardants were usually added to matrix to improve its mechanical properties and flame retardant performance.In this paper,firstly,the surface modification of basalt fiber（BF）was carried out,and the effect of BF on the mechanical properties and flame retardancy of flame-retardant EVA composites was studied.Subsequently,gallic acid（GA）modified magnesium hydroxide（MH）was used to improve the flame retardant properties of EVA composites.And the modified basalt fiber and magnesium hydroxide were added into EVA matrix to study the mechanical properties of flame-retardant EVA composites.Flame retardant properties of composites were studied by limiting oxygen index（LOI）,vertical combustion test（UL-94）,cone calorimetry（CCT）and other tests.And the mechanical properties were studied by tensile test and unnotched impact test.The specific research work of this paper was as follows:1 This article take BF as a functional filler to improve the mechanical properties of flame-retardant EVA,and studied the effect of adding basalt fiber on the flame-retardant properties of composites by hydrolyzedγ-aminopropyltriethoxysilane（KH550）grafted and reacted with the hydroxyl groups on the surface of the basalt fiber.The reaults showed that the addition of modified basalt fiber can improve the mechanical properties of composite.Compared with those of EVA/MH composites,the tensile strength of the composites with 15 phr modified basalt fiber increased by 34.8%,the impact performance was increased by 47.8%,and its flame retardant performance was not significantly damaged.2 In order to further improve the flame-retardant performance of EVA composites,the complex of biomass gallic acid（GA）and Fe³⁺was used to modify magnesium hydroxide.And the polyphenol structure on GA was used to introduce Fe³⁺that had a catalytic effect on carbon formation to form a highly effective flame retardant.According to comparing the GA modified magnesium hydroxide（MH@Fe-GA）with pure magnesium hydroxide（MH）and stearic acid modified magnesium hydroxide（MH@SA）,the results showed that GA was successfully grafted on the surface of magnesium hydroxide,and the median diameter was reduced from 5.4μm to 2.9μm,mainly distributed in 0.9μm～6.0μm;the particle size of MH@SA was between MH@Fe-GA and MH,the lipophilic effect was better than GA modified magnesium hydroxide.3 The MH,MH@SA and MH@Fe-GA were added to the EVA matrix to prepare composites.It was found that the MH modified by GA showed excellent flame retardant and smoke suppression properties.The vertical combustion test passed the V-0 level successfully.Compared with EVA/MH composites,EVA/MH@Fe-GA’s peak heat release rate was reduced by 82.6%,and the total smoke production was reduced by 55%.The modified basalt fiber was added to EVA/MH,EVA/MH@SA和EVA/MH@Fe-GA composites.After that,compared with EVA/MH,the tensile strength and impact strength of EVA/MH@Fe-GA-MBF increased by 40.9%and 115.1%,respectively.In this paper,a simple and low-cost method was used to modify the surface of basalt fiber and magnesium hydroxide.The mechanical properties and flame retardant properties of the flame retardant EVA composites obtained were significantly improved.The method in this paper provided experimental and theoretical basis for improving the practicability and effectiveness of flame-retardant EVA composites.