Optimization And Application Of Trans-1,4- Polyisoprene By Solution Polymerization

Trans-1,4-polyisoprene,in the transition position in the rubber-plastic material spectrum,is a kind of material with strong crystallization ability,high hardness and good dynamic performance.Due to the high order and low internal friction of polymer chain,TPI is of low dynamic heat build-up.When combined with other conventional general rubber,the microcrystalline phase in the system can significantly improve the flex fatigue resistance properties of the blends.Therefore,TPI is especially suitable for high performance green tires.By controlling the crosslinking degree,the loss factor of TPI in middle and high temperature region can be much larger than that of traditional damping material such as chlorinated butyl rubber,which indicates that TPI has great potential in middle and high temperature damping.At present,the main way to synthesize TPI is mainly the bulk method,but it has disadvantages such as difficulty in heat dissipation and controlling the product quality.However,the solution method adopted in this paper can solve these problems well and provide another promising way for the industrialization of TPI.In this paper,TPI was synthesized by the solution method using the supported Ziegler-Natta catalyst.Firstly,the optimal polymerization conditions for synthesis were obtained through 30ml lab-scale experiments.Then 1000ml simulated amplification experiments were carried out.By controlling the polymerization conditions,the product morphology can be controlled to be loose granular.The microstructure and thermal properties were investigated by ¹H-NMR,¹³C-NMR,DSC,XRD and other analysis.The results showed that the products were of high trans-1,4-configuration?>97%?and contains a small amount of cis-1,4 and 3,4-configuration.TPI has the ability to crystallize in two different crystalline forms??-form?monoclinic?and?-form?orthorhombic??,and?-form with melting point at about 68.5?is dendritic spherulite,and?-form with melting point at about 48.5?is black cross spherulite.With shore A hardness between 93-95,tensile strength between 30-34Mpa,elongation at break between 550%and 600%and tear strength around 75kN/m,the prouducts exhibted as a low-melting plasticThe synthesized TPI was blended with natural rubber,and the effects of amounts of TPI and vulcanization system on the curing characteristics,mechanical properties and flexural fatigue properties of the TPI were studied.The results showed that when the proportion of TPI was 20,the amount of accelerator DM was 1.0,and the vulcanization system adopted the ordinary sulfur vulcanization system,the comprehensive performance of the TPI/NR was best.A series of trans-1,4-poly?butadiene-co-isoprene?copolymers?TBIR?were successfully synthesized by solution polymerization using the catalyst system TiCl₄/MgCl₂-Al?i-Bu?₃,which was aimed to improve the processing and blending property of TPI by reduceing the number-average length of isoprene sequence and disturbing TPI segment stereoregularity.The influence of feed ratio of Bd to Ip on dyad and triads sequence distributions,the number-average sequence length and the sequence concentration of the copolymers,and the relationship between the chain structure and the thermal performance was further studied.The results showed the resulting copolymers were mainly of high trans-1,4-configuration in both Ip unit?>97%?and Bd unit?>97%?.with the increase of feed ratio,the butadienen content in the copolymers increased from 10.1%to 57.2%,similarly,the number-average sequence length of butadiene increased from 1.8 to 3.0,while the number-average sequence length isoprene decreased greatly from 16.1 to 2.2.The butadiene content in the copolymer and number-average length of isoprene sequence and butadiene sequence were in good correlation with the glass transition,crystallization and melting behavior and thermal stability of copolymers.