Gas Phase Polymerization Of 1,3-butadiene:an Investigation On The System And Process Of Polymerization

Gas-phase polymerization,by reason of using no organic solvents,is a eco-friendly technol-ogy with simple process and high efficiency and has been widely applied in polyolefin industry.Butadiene Rubber,a kind of synthetic rubber with great importance,is still produced by tradi-tional solution polymerization.It will make a breakthrough for synthetic rubber industry utilizing gas-phase polymerization in polybutadiene synthesis.Based on highly active supported rare earth catalysts with self-owned intellectual property right,the thesis studied gas-phase polymerization of 1,3-butadiene from various aspects.Organic supporter poly(styrene-co-divinylbenzene)(PS-DVB)was synthesized,and gas-phase polymerization of butadiene was performed with PS-DVB supported rare earth catalysts.Elas-tic granular composites contain high cis-1,4 content(>98%)polybutadiene with an Mn of 5.3-5.5×105 were obtained.The micromorphology of the granules was also characterized by scanning electron microscopy.A significant influence on apparent activities of catalysts and appearance of products made by the dispersants used in gas-phase polymerization was confirmed.For studying the role of dispersants in gas-phase polymerization,the behavior of the polymer-ization affected by different kinds of silica particles as dispersants was investigated.Based on the experimental phenomena,a "particle covering" model was presented to elucidate the mechanism of interaction between dispersants and supported catalysts which leads to the mass transfer resis-tance for gaseous monomers.According to this model,a novel dispersant consisting of silicas with different particle size was designed.The practice of this novel dispersant showed good results with high apparent catalytic activities and good appearance of products.The kinetic behavior of gas-phase polymerization of butadiene was monitored by mass flow meter.The changes of monomer consuming rate using different dispersants revealed the "particle covering" effect in the initial stage of gas-phase polymerization.A simple kinetic model was also established to describe the polymerization process.Combining gas-phase polymerization apparatus and anionic initiator n-butyllithium(BuLi),the bulk polymerization and copolymerization of gaseous butadiene were performed.In compari-son with rare earth catalytic system,the anionic polymerization was much slower but the relevant products had a different microstructure.The 1H NMR,13C NMR characterization of the products from copolymerization of styrene and gaseous butadiene indicated that styrene did copolymerized but the content was rather low.