Research On Preparation And Application Of EPDM/PP TPV

Thermoplastic vulcanizate(TPV)is a kind of thermoplastic elastomer formed by dispersing rubber in resin by mechanical shearing during vulcanization.The cross-linked rubber particles are dispersed in the continuous phase of resin in micron size.This kind of"sea-island"structure gives TPV the conventional vulcanized rubber's resilience and impact resistance,as well as the resin's good processing performance and reusability.As a result,it has attracted widespread attention and has become a development trend to replace non-recyclable thermoset rubber.Based on this,this article prepared EPDM(ethylene propylene diene rubber)/PP(polypropylene)TPV through a dynamic vulcanization method,and applied it to the toughening of PP and PP/Starch composites.Finally,on the basis of EPDM/PP TPV,a new type of EPDM/PP/PBE(propylene-based elastomer)TPV was developed.The research content mainly includes:(1)EPDM/PP TPV was prepared by dynamic vulcanization,and the effects of PP type and cross-linking agent dosage on its properties were investigated.The research results showed that EPDM/H-PP TPV prepared by H-PP(homo polypropylene)had better comprehensive mechanical properties,with a tensile strength of 8.9 MPa,an elongation at break of 564%,and the crystallinity reached 29.8%as characterized by differential scanning calorimeter(DSC);Observation by scanning electron microscope(SEM)showed that the rubber phase dispersion in EPDM/H-PP TPV was the best,which made it have better melt fluidity.With the increase of the amount of cross-linking agent,the cross-linking degree and cross-linking rate of TPV continued to increase,the mechanical properties were also improved,but the melt fluidity decreased;When the amount of crosslinking agent was 0.10 phr(parts per hundred),the comprehensive mechanical properties and melt fluidity of TPV were better.(2)The PP/TPV binary blend was prepared by the melt blending method,and the influence of the amount of TPV on properties of PP/TPV binary blend was studied.Subsequently,on this basis,nano-CaCO₃ and nano-Talc were further added to prepare its ternary blend.The effects of the amount of nano-CaCO₃ and nano-Talc on the properties of PP/TPV/nano-filler ternary blends were studied respectively.The results showed that TPV can effectively toughen PP.When the amount of TPV in the PP/TPV binary blend was only 5 phr,the notched impact strength reached 8.2 k J·m^-2,which was an increase of 95%compared with PP,at the same time,the tensile strength only decreased by 4%.Nano-CaCO₃ could induce the formation of?crystal form in PP.As the amount of nano-CaCO₃ in the PP/TPV/nano-CaCO₃ ternary blend increased,the notched impact strength showed a trend of first increasing and then decreasing,and the tensile strength did not change much.When the amount of nano-CaCO₃ was 3 phr,the impact resistance of the material was the best,reaching 13.8 k J·m^-2,and the heat resistance was also improved.The optimal amount of nano-Talc in PP/TPV/nano-Talc ternary blend was 9 phr,and the notched impact strength of the composite reached 19.32 k J·m^-2,which was 4.5 times of that of pure PP,and the tensile strength increased to 40.92 MPa.(3)PP/Starch/TPV composites were prepared by melt blending method,and the influence of TPV dosage on the mechanical properties,crystallization properties,rheological properties,thermal stability,aging resistance and micromorphology of the composites was explored.The results showed that with the increase of TPV dosage from 0 to 10 phr,the notched impact strength of PP/Starch/TPV composite increased from 3.43 k J·m^-2 to 8.74 k J·m^-2,an increase of1.5 times,while the tensile strength did not change much;TPV slightly reduced the melting point and crystallinity of the composites,but increased the thermal stability and aging resistance.The retention rate of tensile strength after aging rose from 45.76%to 70.25%,and the retention rate of elongation at break increased from 13.32%to 32.40%;The test of rheological properties showed that the rubber cross-linked particles formed a strong physical network structure in the PP matrix,and the chain entanglement and interaction on the interface with PP matrix were strong.(4)EPDM/PP/PBE TPV was prepared by dynamic vulcanization method,the effects of PBE content on the mechanical properties,resilience,Shore hardness,melt flow rate,crystallization,rheological properties and micromorphology of EPDM/PP/PBE TPV were investigated,the results showed that with the continuous increase of the amount of PBE,the viscosity ratio increased from 6.13 to 8.94,the particle size of the rubber cross-linked particles continued to decrease,and the morphology became more complete and detailed;When the PBE content was 20 phr,the tensile strength of EPDM/PP/PBE TPV reached 14.92 MPa,the elongation at break reached 1665%,which increased by 67.6%and 195.2%respectively compared with TPV without PBE.The resilience was also improved obviously,and the crystallinity decreased by 12.8%,and the Shore hardness decreased by 10 A,but the melt flow rate remained at 0.5 g/10min.Analysis of surface properties and interface compatibility showed that PBE and EPDM had lower interfacial tension and stronger interactions.