Properties Of Ethylene-vinyl Acetate Rubber/polyamide Blend Thermoplastic Elastomer

Ethylene-vinyl acetate rubber(EVM)and Nylon terpolymer(tPA)were used as the matrix,EVM/tPA thermoplastic elastomers were prepared by dynamic vulcanization technology.The effects of the dynamic vulcanization process on the processing rheological performance,mechanical properties,thermal stability,microscopic phase structure and dynamic mechanical properties of EVM/tPA TPE were investigated.Firstly,the curing system of EVM and EVM-GMA were studied.The effect of DCP and TEOS/DBTO content on the properties of EVM were investigated.The experimental results showed that the curing temperature showed little effect on the curing charateristics of the EVM compound with TEOS/DBTO;DCP showed obvious effect on the curing charateristics.With the increase of DCP content,the curing rate and crosslink density of EVM compound gradually increased.The mechanical properties of EVM vulcanizate showed optimum value with 8phr TEOS.While the mechanical properties of EVM-GMA vulcanizate showed optimum with 6 phr TEOS.The tensile strength of EVM rubber vulcanizate increased with the amount of DCP and reached maximum value of 19.8MPa,while the tensile strength of EVM-GMA vulcanizate showed a maximum value of 20.1MPa.The hot air aging experiment showed that the mechanical properties of EVM vulcanizate increased after aging.After10 days of aging,the tensile strength of EVM vulcanizate with DCP dosage of 5phr reached 20.3MPa,which was 2.5% higher than that of unaged EVM vulcanizate,while the mechanical properties of EVM-GMA vulcanizate decreased significantly after aging,but still remained at a high level,indicating that EVM and EVM-GMA vulcanizate had good aging resistance.Secondly,the mechanical properties,thermal stability and micromorphology of EVM/tPA thermoplastic elastomers were investigated.The results showed that the peroxide can effectively vulcanize the EVM(EVM-GMA)/tPA blends dynamically and the blends had excellent overall properties.With the increase of DCP dosage,the optimum values of tensile strength existed for the thermoplastic elastomer,and there was no significant change in hardness.The results of SEM,DSC and dynamic mechanical properties showed that the increase of DCP dosage can improve the compatibility of the two phases to a certain extent,and the best compatibility was achieved when the dosage of DCP was 3.2phr.The Thermogravimetric Analysis(TGA)showed that the thermoplastic elastomer had better thermal stability.According to the high temperature oil resistance results,the high temperature oil resistance of EVM/tPA thermoplastic elastomers improved with increasing DCP dosage.Comparing the two EVM/tPA thermoplastic elastomers at the same DCP dosage,the EVM-GMA/tPA thermoplastic elastomer showed higher mechanical properties,better oil resistance and heat resistance.Finally,the influence of the process conditions on the properties of the thermoplastic elastomer was investigated.The results showed that the mechanical properties of the EVM/tPA thermoplastic elastomer improved with the increase of rotor speed,and showed optimum tensile strength at a rotor speed of 80 rpm.The residual strain of the thermoplastic elastomer decreased with increasing rotor speed,resulting in better elasticity;the EVM-GMA/tPA thermoplastic elastomer showed better reprocessing properties.Increasing rotor speed improved the oil resistance of the thermoplastic elastomer.As the mixing temperature increased,it had less effect on improving the compatibility of the two phases and reduces the oil resistance of the thermoplastic elastomer.