Study On The Construction And Performance Of EPDM/SR Blend Phase Interface

Silicone rubber(SR) has excellent resistance to high and low temperatures and good electrical insulation.At the same time,the SR industry has a low dependence on petroleum,it has developed rapidly in recent years and has become more and more widely used.However,its high cost and low mechanical strength limit its wide application in many fields.EPDM rubber(EPDM)has the advantages of high mechanical strength,good aging resistance and low cost,but its high temperature resistance is not good.The combined use of EPDM and SR can reduce costs,and at the same time can improve the processing performance and high and low temperature resistance of the combined materials.However,the compatibility of EPDM and SR is poor.After blending,phase separation and uneven dispersion of blended components will occur.Therefore,to prepare EPDM/SR blends with good performance,it is necessary to add a compatibilizer,which differs in compatibility.Different interface layer structures have different effects on the mechanical properties,damping and aging resistance of the material.In this paper,EPDM/SR blend was used as the matrix,and compatibilizers were added to the blend system to study the interface layer structure and the effect of the interface effect on the material properties.When EPDM-g-MAH was added only to the EPDM phase,the maleic anhydride group may react with the silanol on the surface of the silica in the SR phase to increase the interfacial interaction of the blend,but the addition of EPDM-g-MAH reduced the crosslinking density of the blend,and thus increased the stress relaxation and creep behavior of the system.In addition,the addition of EPDM-g-MAH increased the proportion of EPDM in the system,which reduces the thermal stability of the blend.When ?-aminopropyltriethoxysilane(KH550)was only added into SR phase,the silanol produced by the hydrolysis of the siloxane in KH550 can react with the silanol on the surface of the silica in the SR phase,making the dispersion of silica in the SR phase better,increased the crosslinking density of the system while increasing the physical crosslinking point,so the stress relaxation and creep degree of the blend decreased,and the existence of KH550 enhanced the thermal stability of the blend.When EPDM-g-MAH and KH550 were added to EPDM phase and SR phase simultaneously.Each compatibilizer not only played a role in a single phase,but also generated amide bonds between the phase interface due to the high reactivity of maleic anhydride group and amino group,which increased the interfacial cross-linking of the blend.The crosslinking density of the blend further increased,and the degree of stress relaxation and creep decreased accordingly.Enhancing the interphase force of EPDM/SR blend could improve the resilience of the material,and the enhancement of the interphase force increased the modulus of the blend.However,the damping effect of constrained damping structure is only affected by the stiffness of the material under the condition that the outer dimensions of the material are the same.Within a certain range,the material stiffness increased,the corresponding natural frequency increased,the shear deformation ability also increased,and the damping effect increased.The properties of blends with different interface structures vary after aging.The performance of the blend system without any compatible components gradually decreased with the increase of aging temperature and aging time.The mechanical properties of the blend system that only EPDM-g-MAH added in decreased first and then increased with the extension of aging time,and the properties gradually decreased with the increase of aging temperature.The addition of KH550 did not contribute to the interfacial interaction of the system,but it makes the silica in the SR phase better disperse.Therefore,the mechanical properties of the blend system changed little with the aging time,but decreased slightly with the increase of aging temperature.The mechanical properties of the blend system with the addition of compatible components in the two phases showed a similar trend with that of the system that EPDM-gMAH added in with the aging temperature.However,due to the presence of KH550,the mechanical properties of the blend system were greatly improved after aging.The existence of interface crosslinking layer improves the aging stability of materials,the aging activation energy of the system without interface effect is low,while that of the system with good interface effect is high.