高间规苯乙烯共聚合及对加工性能的影响OA

Using a pyridinylmethylene fluorenyl yttrium complex as the main catalyst,solid methylaluminoxane as a co-catalyst,and triisobutylaluminum as a chain transfer agent,syndiotactic copolymerization of styrene(St)with p-methylstyrene(p-MS)and p-tert-butylstyrene(p-tBS)was achieved at 140℃,yielding two types of syndiotactic styrene copolymers.The influence of comonomer content on the crystallization behavior,thermal properties,mechanical performance,and processing flowability of the copolymers was investigated.The results indicated that increasing the content of either comonomer significantly reduced the melting point and crystallinity of the syndiotactic copolymers,thereby broadening the processing window:the melting point decreased from approximately 270.0℃for pure sPS to 207.8℃,while crystallinity dropped from 50%to 30%.Although crystallinity decreased,tensile strength remained well maintained.The copolymer containing 20%(molar percent)p-methylstyrene exhibited a tensile strength of 40.6 MPa,while the copolymer containing 20%(molar percent)p-tert-butylstyrene reached 44.4 MPa.Furthermore,the melt flow index of the copolymer samples outperformed that of the pure sPS reference sample(Idemitsu's pure syndiotactic polystyrene,grade SPS-130),demonstrating excellent processing fluidity.