Preparation And Properties Of Elastomer EVM Supercritical Foaming Material

In this paper,ethylene-vinyl acetate rubber(EVM)was successfully prepared by intermittent foaming method and modified by carbon nanotubes(CNT),styrene thermoplastic elastomer(SEBS),Ammonium polyphosphate(APP)and silica(SiO₂)aerogels respectively with EVM was used as raw materials.The physical and mechanical properties,self-healing properties,damping properties and flame retardancy properties of EVM composite foam materials were studied as follows:The conductive self-healing EVM nanocomposite foam material was successfully prepared by solution blending method and batch foaming method.The effects of CNT content on the physical and mechanical properties,electrical conductivity,self-healing properties and cell morphology of EVM nanocomposite foam materials were studied.The research results show that with the increase of CNT content,the density,hardness,tensile strength and tear strength of EVM nanocomposite foam materials gradually increase,and the expansion ratio and resilience gradually decrease;the electrical conductivity increases with the increase of CNT content,The maximum conductivity is7.5×10^-7S/m;the self-healing efficiency increases with time,and the maximum self-healing efficiency is 93%.The maximum conductive self-healing efficiency is66.7%;with the increase of the CNT content,the cell size of the EVM nanocomposite foam material gradually decreases,and the cell wall gradually becomes thicker.EVM/SEBS blended foam materials with high damping and wide temperature range were prepared by melt blending method and batch foaming method.The effects of the amount of vulcanizing agent and SEBS on the physical and mechanical properties,damping properties and cell morphology of EVM/SEBS blended foam materials were studied.The research results show that as the amount of SEBS increases,the density and resilience of EVM/SEBS blended foam materials gradually decrease,the expansion ratio,hardness,tensile strength,and tear strength gradually increase,and the cell size gradually decreases.The addition of SEBS reduces the damping performance at lower temperatures and improves the damping performance at higher temperatures.The research results also show that as the amount of vulcanizing agent increases,the hardness,resilience,tensile strength and tear strength of EVM/SEBS blended foam materials gradually increase,the elongation at break gradually decreases,and the cell distribution becomes more uniform.The maximum effective damping temperature range is 60.1?.EVM halogen-free flame-retardant foam materials were prepared by melt blending method and batch foaming.The effects of APP,SiO₂ aerogel,APP and SiO₂aerogel on the cell morphology,physical and mechanical properties and flame retardancy of EVM foam materials were studied.The research results show that as the amount of APP increases,the density,hardness and limiting oxygen index of the EVM foam material gradually increase,and the expansion ratio and elongation rate continue to decrease;the cell size gradually decreases,and the cell wall gradually becomes thicker.The research results also show that with the increase in the amount of SiO₂aerogel,the density,hardness,tensile strength,tear strength and limiting oxygen index of EVM foam materials continue to increase,and the foaming ratio,resilience and elongation continue to decrease.The cell size gradually becomes smaller.The research results also show that with the increase in the amount of SiO₂ aerogel,the density,hardness,tensile strength and tear strength of EVM foam materials with different ratios of APP and SiO₂ aerogel continue to increase,and the foaming ratio and resilience When the ratio of APP and SiO₂ aerogel is 140/60,the limiting oxygen index of EVM foam material can reach 42;the cell size of EVM foam material shows a trend of first increasing and then decreasing;The EVM foam material with 180 parts of APP and 20parts of SiO₂ aerogel has the lowest overall heat release rate,the lowest total heat release,the largest fire performance index,the smallest fire risk,and the best flame retardant performance.