Thermal Viscoelastic Damping Properties Of Modified EPDM Elastomer

Ethylene propylene diene monomer(EPDM)is a typical thermoplastic elastomer with excellent physical and mechanical properties,heat-resistant air aging,ozone aging resistance,etc.However,the glass transition temperature of single-component EPDM is low and the effective damping temperature range is narrow,especially the damping performance at room temperature and above is poor.In this paper,EPDM/crosslinked polyethylene recycled material(RXLPE),EPDM/epoxidized natural rubber(ENR)binary blend and EPDM/ENR/butadiene rubber(BR)ternary blend were prepared by filling modification and blending modification.The vulcanization characteristics,processability,physical and mechanical properties and damping properties were characterized and studied.The main work and results are as follows:(1)EPDM modified elastomer was prepared by filling EPDM with RXLPE.The study shows that the higher the RXLPE content,the smaller the EPDM equilibrium torque.The reduction of the fitting parameter K1/a of the vulcanization kinetic model shows that the vulcanization rate of the compound is reduced after RXLPE is filled with EPDM.The tensile strength and tear strength of EPDM increased with the increase of RXLPE content,and the mechanical properties improved.The strain scanning of rubber processing analyzer(PRA)shows that RXLPE filling EPDM improves the shear damping property of vulcanizates.The dynamic mechanical thermal analyzer(DMA)shows that the loss factor decreases after RXLPE filling EPDM,but the glass transition temperature of EPDM shifts to the high temperature direction,and the damping property improves in the high temperature environment higher than 20?.(2)EPDM/ENR blend was prepared by blending ENR and EPDM.The blending of ENR and EPDM increased the vulcanization reaction speed of the compound,and the positive vulcanization time(T90)decreased first and then increased with the increase of ENR content.With the increase of ENR content,the Payne effect of EPDM/ENR compound decreases.RPA strain scanning and frequency scanning show that the damping factor of the compound is higher than that of each single component.DMA temperature scanning shows that the ENR and EPDM blend show two independent damping internal friction peaks.With the increase of ENR content,the damping peak of EPDM shifts to the low temperature direction and the damping peak of ENR shifts to the high temperature direction.Therefore,blending ENR with EPDM broadens the application range of EPDM effective damping,and the blending ratio of EPDM:ENR=60:40 has the best damping performance.(3)Si69-EPDM/ENR composite was prepared by modifying EPDM/ENR blend with silane coupling agent(Si69).The study showed that the addition of Si69 to EPDM/ENR prolonged T90 of the compound,decreased CRI and decreased vulcanization rate.Shear viscosity r1 increases gradually,Payne effect decreases and carbon black dispersity increases.Si69 increases the tensile strength of EPDM/ENR first and then decreases,and increases the tear strength.RPA strain scanning shows that the addition of Si69 to EPDM/ENR increases the loss factor of vulcanizates and improves the damping performance.DMA temperature scanning shows that the damping peaks corresponding to the two phases move slightly towards high temperature,while the height and width of the damping peaks do not change much.Considering comprehensively,the mechanical properties and damping properties of EPDM/ENR are the best when the dosage of Si69 is 2 phr.(4)EPDM/ENR/BR ternary damping material was prepared by blending cis-polybutadiene rubber(BR)and EPDM/ENR.Blending BR with EPDM/ENR shortened T90 of the blend.T90 decreased with the increase of BR content,and the balance torque decreased.The fitting parameter K1/a of vulcanization kinetics model increases with the increase of BR content,which indicates that blending BR with EPDM/ENR improves the vulcanization rate of the compound.RPA strain scanning showed that blending BR with EPDM/ENR reduced the storage modulus G' of EPDM/ENR/BR vulcanizates,increased the loss factor and improved the damping performance.The fitting of Payne effect by Kraus model shows that the addition of BR improves the dispersibility of carbon black in rubber matrix.DMA temperature scanning results show that when BR is added,the damping peaks of the two phases are close to each other,and the height of the damping peaks increases.When 20 phr of BR is added,the peak value of EPDM increases most obviously,from 0.172 to 0.243.The damping peak slightly shifts to the high temperature direction,from-37.2? to-30.3?,and when 10 phr of BR is added,the peak value of ENR increases most obviously,from 0.378 to 0.481.