| The excellent performance of random copolymer polypropylene（PPR）has received much attention from industry and research community,but its use environment is limited by its brittleness at low temperatures.The preparation of PPR composites with excellent low-temperature toughness and toughness balance has become a hot topic in the field of polymer toughening and modification,and the related research is of great scientific significance and application value.In recent years,the use of rubber,nanoparticles and micro-crosslinking synergistic toughening of PPR has achieved a series of results and become a research hotspot.In this thesis,starting from the development of advanced compound rubber with excellent toughening properties（including high strength and high toughness）,the toughening effect and mechanism of compound rubber on PPR are investigated,and on this basis,the synergistic toughening effect,toughening mechanism and processing performance of nanoparticles,microcrosslinking and compound rubber are studied,with a view to providing theoretical basis and practical experience for the preparation of PPR with excellent comprehensive performance.The main research results of this thesis are as follows:（1）.The EPR/IR compound rubber was prepared by blending ethylene propylene rubber（EPR）and isoprene rubber（IR）with dynamic vulcanization of diisopropyl peroxide（DCP）,and the effect of DCP content on the mechanical properties of the compound rubber was investigated.The results showed that the tensile strength and toughness of the resulting EPR/IR compound were 4～5 times higher than those of pure EPR and IR when DCP was added in 2 parts,and the EPR/IR（40/60）ratio had the best performance with excellent energy dissipation and deformation recovery ability.On this basis,the higher strength EPR/IR/Si O2 composite rubber was prepared by introducing nano-Si O2 particles into the EPR/IR composite rubber.（2）.The EPR/IR composite rubber was used as the toughening component to investigate the efficiency of EPR/IR ratio on the toughening of PPR.The impact test results showed that the optimal ratio of the composite rubber to toughen PPR was between 7/3 and 8/2,and the brittle toughness transition temperature(Tbd)of PPR/（EPR/IR）was greatly reduced from-20℃to-30℃compared with that of PPR/EPR alloy.nano-Si O2,PPR/（EPR/IR）/Si O2 composites with better low-temperature toughness and strength-toughness balance were prepared.The PPR/（EPR/IR）/Si O2 composites could reach an impact strength of 41.9 k J/m2 at-30°C and Tbd as low as-40°C.The phase morphology analysis revealed that the nano-Si O2 particles were distributed at the interface between（EPR/IR）and PPR,which enhanced the toughening and strengthening effect by inhibiting the coarsening of the rubber phase and increasing the interfacial area by changing the shape of the dispersed phase.（3）.In this part,the compound rubber（EPDM/IR）was chosen to investigate the toughening efficiency and mechanism of the compound rubber and microcrosslinking on PPR.Firstly,the effect of EPDM/IR ratio on the mechanical properties of PPR was investigated,and the optimum ratio of（EPDM/IR）toughened PPR was found to be 8/2.On this basis,the effect of the degree of crosslinking on the mechanical properties of PPR/（EPDM/IR）composites was investigated.The results showed that the yield strength and modulus of elasticity of the microvulcanized PPR/（EPDM/IR）materials were improved by20%compared with the unvulcanized samples while maintaining good low-temperature toughness at an optimum content of 1 part of vulcanizing agent.Dynamic mechanical tests showed that microvulcanization could increase the compatibility between EPDM and IR in the compound rubber phase,and the phase morphology study showed that microvulcanization could reduce the rubber particle size and increase the interfacial area,which played a synergistic toughening effect with the compound rubber. |
