摘要
Abstract
By using nano-montmorillonite modified spherical magnesium chloride as a carrier,a Ziegler-Natta catalyst was prepared.This catalyst was employed in single-reactor multi-stage polymerization to simulate a three-reactor continuous process for synthesizing ultra-rigid and ultra-tough polypropylene.The effects of polymerization conditions,specifically hydrogen partial pressure,alkylaluminum dosage,ethylene partial pressure,and propylene-to-ethylene molar ratio,on the properties of the resulting polypropylene were examined.The results demonstrate that increasing hydrogen partial pressure increases the melt flow rate(MFR)of the first-stage polypropylene homopolymer,while tensile properties and impact properties change insignificantly.In the second stage,ethylene polymerization synthesizes an appropriate amount of ultra-high molecular weight polyethylene within the pores of the porous polypropylene particles formed in the first stage,thereby enhancing mechanical properties such as impact strength and tensile strength.Under optimal conditions,the synthesized polypropylene exhibits an MFR(10 min)of 34.6 g,a tensile strength of 32.1 MPa,a room-temperature notched impact strength of 33.4 kJ/m2,and a flexural modulus of 1 565 MPa.Compared to the K9928H product,the synthesized polypropylene shows a 1.8 fold increase in notched impact strength,a 36.1%improvement in flexural modulus,and a 35.4%enhancement in tensile strength.关键词
纳米蒙脱土改性载体/Ziegler-Natta催化剂/分段聚合/聚丙烯Key words
modified carrier of nano-montmorillonite/Ziegler-Natta catalyst/multi-stage polymerization/polypropylene分类
化学工程
