Synthesis Of Ethylene Propylene Rubber By Ziegler-Natta Vanadium Catalytic System With Activator

At present,the catalytic system used in the industrial production of ethylene propylene rubber is still mainly Vanadium-based(V-based)catalytic system,but V-based catalyst has the disadvantages of easy deactivation of active sites and low catalytic perfomance.In this paper,the active centers of V-based catalyst were stabilized by adding activator into the VO(OEt)Cl₂-EASC catalytic system.The effects of activators on ethylene/propylene copolymerization and ethylene/propylene/ethnobornene(ENB)ternary copolymerization of V-based catalytic system were investigated.The influnce of different amounts of cocatalysts on the polymerization performance of V-based catalytic system containing activators were also investigated.The keypoints of this paper are as follow:The activators of ethyl trichloroacetate(ETCA),hexachloropropylene(HCP)or dichlorophenyl ethyl acetate(DCPAE)were added into VO(OEt)Cl₂-EASC catalytic system respectively,and EPM and EPDM were synthesized.The experimental results showed that the catalytic activity of ETCA was significantly improved in the synthesis of EPM.When n(Al)/n(V)was 20,the catalytic activity was increased by 162%compared to the one without the addition of ETCA.Futhermore,the activator of HCP and DCPAE increased the catalytic activity by 42%and 65%,respectively.In the synthesis of EPDM,activator DCPAE possessed the best improvement performance.When n(Al)/n(V)was 20,the catalytic activity increased by 187%compared to the one without activator,while ETCA and HCP increased by 63%and 69%,respectively.The three activators can increase the content of propylene monomer,decrease the molecular weight,increase the content of random sequence,reduce the content of long ethylene chain sequence and lower the glass transition temperature.Activator HCP and activator DCPAE can also widen the molecular weight distribution of rubber.The molecular weight,ethylene content and random sequence content of EPM can be slightly increased by increasing the amount of cocatalyst,but the molecular weight distribution and glass transition temperature are not significantly affected.The three activators can reduce the ENB content,molecular weight and random sequence content of EPDM and have no effect on the glass transition temperature of rubber.In addition,activator ETCA can narrow the molecular weight distribution of rubber.Activators HCP and DCPAE can significantly reduce the content of long ethylene chain sequences in rubber.With the increase of the amount of cocatalyst,the content of ENB in rubber increased.Meanwhile,The change of the amount of cocatalyst had no obvious effect on the content of long ethylene chain and the glass transition temperature.