Preparation And Properties Of Ethylene Propylene Diene Monomer/polypropylene/unsaturated Carboxylate Composites Via Dynamic Vulcanization

Thermoplastic vulcanizate(TPV)is a special thermoplastic elastomer material with excellent properties.It makes the rubber undergo cross-linking reaction by dynamic vulcanization,and the rubber phase is finally sheared into particles dispersing in the continuous phase of plastic.TPV can be obtained by existing plastics and rubbers via the dynamic vulcanization,which has better performance than the simple blending.TPV is an eco-friendly material,due to its repeatable processing and recyclable properties that traditional vulcanizates do not have.A large number of polymers are thermodynamically incompatible,with the inferior interfacial interaction and adhesion,which leads to the failure of these polymer blends under the action of loads.Therefore,improving the interaction between polymer interfaces is of great significance to the properties of the blends.Ethylene propylene diene monomer(EPDM)/polypropylene(PP)TPV is the earliest developed TPV,which is quite mature in manufacturing and processing.It has been widely used in industrial fields.Although it has excellent electrical insulation properties,ozone aging resistance and processability,it also has the problem of poor interface compatibility between EPDM and PP.Unsaturated carboxylates are a type of fillers with double bonds that are usually used as the rubber reinforcing agents.They can undergo complex self-polymerization and grafting reactions initiated by peroxide radicals.These products play a role in promoting cross-linking and reinforcement of the rubber.The purpose of this dissertation is to increase the compatibility of the incompatible blends by using unsaturated carboxylates.By introducing magnesium acrylate(Mg MA)or sodium methacrylate(NDMA)into EPDM/PP TPV blends,the interface of blends was compatibilized by Mg MA(NDMA),and the effect of compatibilization on performance was systematically studied through testing and characterization.Based on the research of NDMA for compatibilization,silica and NDMA were used together and added into EPDM/PP blends.The reinforcing effect of silica on TPV was further investigated.The research results show that the prepared TPV is a"sea-island"structure with PP as the continuous phase and EPDM as the dispersed phase.Mg MA(NDMA)will self-assemble to form Poly-Mg MA(Poly-NDMA)and link with EPDM and PP molecules.Poly-Mg MA(Poly-NDMA)locate in the EPDM phase and PP phase reinforcing the TPV system,and the grafted products present at the interface can play a compatibilizing role for the two phases.The addition of unsaturated carboxylates increased the cross-linking density of the EPDM phase and enhanced the mechanical properties of the TPV.With the increase content of unsaturated carboxylate in the TPV,the tensile strength,stress at 100%strain and complex viscosity of the blends evidently improved.The elongation at break has little change.Furthermore,the addition of unsaturated carboxylate endows the TPV with excellent shape memory performance,and the overall retention of R_f and R_r can reach to more than 90%.Unsaturated carboxylate also helps to improve the shape recovery rate.The higher the content,the faster the recovery rate.In the EPDM/PP/NDMA/silica TPV composites prepared by dynamic vulcanization,NDMA improves the compatibility between PP and EPDM,and silica improves the mechanical properties of TPV.The tensile strength and the stress at 300%strain enhanced significantly with the increase content of silica.However,the change of elongation at break is not obvious and remains above 350%.In addition,the introduction of NDMA and silica improves the storage modulus and complex viscosity of TPV,and reduces the stress softening effect.