摘要
对采用管式反应器在不同工艺条件下得到的低密度聚乙烯进行表征,研究了工艺参数对低密度聚乙烯分子结构与性能的影响.结果表明:将峰温1或者峰温4提高3℃可以使重均分子量(Mw)提高700.0～2 000.0,而数均分子量(Mn)下降600.0～700.0,同时使短支链含量提高0.100 0～0.300 0 个/1 000 C;压力每升高1 MPa,Mw升高623.0,Mn提高98.5,同时使短支链含量下降0.084 1 个/1 000 C;丙烯、丙醛进料速率每提高1 kg/h,Mw分别下降92.5,896.4,相对分子质量分散系数分别降低0.002 6,0.032 5,而丙烯的进料速率每提高1 kg/h,可以使短支链含量提高0.003 6 个/1 000 C.该结果可以辅助转产过程中的工艺参数调整以快速实现目标产品的生产.
Abstract
Low-density polyethylene(LDPE)obtained under various conditions in an industrial tubular reactor were characterized.The effects of process parameters on molecular structure and properties of LDPE were investigated.The results show that the weight-average molecular weight(Mw)of the products is increased by 700.0-2 000.0 when increasing the Peak temperature 1 or 4 by 3℃,while the number-average molecular weight(Mn)is decreased by 600.0-700.0 and an increase of short-chain branching(SCB)by 0.100 0-0.300 0/1 000 C.Mw and Mn rise by 623.0 and 98.5 and SCB falls by 0.084 1/1 000 C when the pressure is improved by 1 MPa.By increasing the feeding rate of propylene and propionaldehyde by 1 kg/h respectively result in the decrease of Mw by 92.5 and 896.4,a decrease of dispersity by 0.002 6 and 0.032 5.SCB is improved by 0.003 6/1 000 C as the feeding rate of propylene is enhanced by 1 kg/h.The results can be used to help adjust the process parameters during grades switch for rapid target products production.
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