Preparation Of High Vinyl Polybutadiene With Asymmetric Ether/Sodium Alkoxide Composited Modifiers System

Because of demands on tire skid resistance, polybutadiene with high vinyl content are of particular interest to tire industry due to the inherently better grip properties. Compared to the other methods, anionic polymerization of high vinyl polybutadiene for the advantage of none gel, variable vinyl content, simple techniques and less pollution cause more and more attention. Besides reaction temperature, modifiers and its dosage were the key factors that influence the vinyl content of products. Developing effective modifiers used at high reaction temperature was always one of the focuses in this realm.In this paper, self-made asymmetric ethers and sodium alkoxides were used as modifiers in anionic polymerization of polybutadiene, in which asymmetric ethers include methyl morpholinoethyl ether(MOEM), ethyl morpholinoethyl ether(EOEM), butyl morpholinoethyl ether(BTE), tetrahydrofufury ethyl ether(ETE) and tetrahydrofufury butyl ether(BTE);sodium alkoxides include sodium salts of tetrahydrofufury alcohol and sodium salts of morpholinoethol.Single modifier system and asymmetric ether/sodium alkoxide composited modifier system were used to prepare polybutadiene with n-BuLi as initiator, cyclohexane as solvent. Modifiers, dosage, reaction temperature were studied on polymerization rate by dilatometer. The false first-order apparent rate constant and activation energy are calculated as well. The microstructures content of the products were calculated by FT-IR.Reaction temperature made great effect on polymerization rate and vinyl content of products by using single modifier system modified butadiene polymerization. It got unwilling effect at high reaction temperature (60-70℃). For accelerating polymerization rate and increasing vinyl content of the products, the single modifier system made same sequence that sodium alkoxide>alkyl tetrahydrofufury ether>alkyl morpholinoethyl ether, and longer the alkyl chain was, weaker the modified ability it was.Composited modifiers system gave quicker polymerization rate and higher vinyl content compared to that of single modifier systems, the much more important was they exhibit well at high temperature, which made them suit to factory work. EOEM/THFAONa andETE/THFAONa were the mostly systems that concern on. The result showed that, with the same condition, ETE/THFAONa system made fastest polymerization rate and wider vinyl content range, while EOEM/THFAONa system gave higher vinyl content products, but narrower vinyl content range.