Study On Preparation And Properties Of Syndiotactic 1,2-polybutadiene

Syndiotactic 1,2-polybutadiene is widely used in our life to produce tyre,binder,short fiber and so on,owing to its excellent thermal aging resistance,wet grip and low heat build-up.Iron catalysts attract much attention due to the high activity and selectivity.The melting point of syndiotactic 1,2-polybutadiene prepared by iron catalysts is typically higher than 160 ^oC,with certain gelatin and agglomeration which is hard to blend with cis-1,4-polybutadiene rubber.In this dissertation,a series of new iron catalysts were developed.The composition and ratio of the catalysts,the effects on properties of polymers encompassing melting point,crystallinity and dispersibility were investigated.Nano-micro syndiotactic 1,2-polybutadiene with good dispersibility in hexane was formed,which acts as fillers with remarkable reinforcement,low rolling resistance.The details as follows:A series of acetylacetone iron catalysts were synthesized for preapring 1,2-polybutadiene with low melting point and high selectivity.The results showed that catalysts with methyl or phenyl in ligand backbone have higher activity,while catalysts with thiophene and halogen have lower activity.The larger steric hindrance in the ligand is helpful to reduce to 144 ^oC and tri-isobutyl aluminum performs higher activity.Blending with cis-1,4-polybutadiene rubber,the formed blendings can be processed under the crosslinking temperature(150 ^oC).A new iron catalyst was designed,which can be used to efficiently synthesize syndiotactic 1,2-polybutadiene with high selectivity and good dispersibility in the hexane.The optimal conditions for polymerization were[M]/[Fe]=2000,[Al]/[Fe]=20,[P]/[Fe]=4,the catalytic efficiency can reach 88.82%,and the proportion of syndiotactic structure can be as high as 97%.The polymer was added as a filler to polybutadiene rubber and higher vulcanization efficiency,modulus,tensile strength and 100%tensile strength were reached,The overall performance is superior to the PB-Si O₂sample modified by adding white carbon black.The defects caused by the addition of a single filler of carbon black were improved in terms of strength and performance after the 15%s PBD is added to the mixed filler,and the overall performance is excellent.Introducing bio-based CS as a carrier to support ferric isooctanoate as a supported catalyst,explored the best conditions for polymerization were[M]/[Fe]=2000,[Al]/[Fe]=30,[P]/[Fe]=4.The catalytic efficiency can reach 83.96%,and the ratio of syndiotactic structure can be as high as96%.The s PBD suspension with an average particle size of 500 nanometers to 1000 nanometers can be obtained through load polymerization.Good dispersion of s PBD in cis-1,4-polybutadiene rubber with high filling content was realized by in-situ blending of suspension.When the addition amount was about 15%,the overall performance was improved the most.