超高分子量聚丙烯的制备

超高分子量聚丙烯（UHMWPP）是一种黏均分子量百万以上，具有超高的强度、超高的耐磨性、较强的抗氧化能力的热塑性工程塑料，可用于制备高强度、高模量、耐腐蚀、抗冲击、耐应力开裂的聚丙烯产品。本工作的目的在于制备出分子量超过200万的聚丙烯，将其用作3D打印材料来解决由于分子链较长引起高熔体黏度和低流动性而导致加工难成型问题。本工作基于传统的Ziegler-Natta催化剂，对主催化剂进行金属离子和有机物的负载，通过控制丙烯的链转移来控制聚丙烯的分子量，并且在聚合反应过程中不加入氢气（带有活性氢的物质），以防止其成为聚合反应的终止剂。研究了聚合反应温度、聚合反应时间、助催化剂和外给电子体对聚丙烯分子量的影响。采用黏度法、升温淋洗分级法等表征了制备的聚丙烯分子量。通过聚合工艺优化，在聚合反应温度70℃、聚合反应时间60min、助催化剂三异丁基铝、外给电子体P Donor下，最终制备出了黏均分子量超过204万的超高分子量聚丙烯。

Preparation of ultra-high molecular weight polyprolene

Ultra-high molecular weight polypropylene (UHWMPP) is a kind of thermoplastic engineering plastics which has viscosity-averaged molecular weight of more than 1 million, along with incredible strength, high wear resistance, strong antioxidant abilities, and thus it can be used to prepare the polypropylene products with high strength and modulus, as well as high resistance to corrosion, impact and stress crack. The main purpose of the study is to produce the polypropylene with molecular weight over 2 million, which can be used as a 3D printing material to avoid the problems of high melt viscosity and low fluidity caused by long molecular chain. Based on the traditional Ziegler-Natta catalyst, the main catalyst was loaded with metal ions and organics. The molecular weight of the polypropylene was controlled by controlling the chain transfer of propylene and hydrogen (active hydrogen-containing substance) was not added during the polymerization to prevent the termination of the reaction. The effects of the polymerization action temperature, polymerization action time, promoters and external electron donors on the molecular weight of polypropylene were investigated. The molecular weight of the prepared polypropylene was characterized by viscometry and temperature rising elution fractionation method. Finally, the ultra-high molecular weight polypropylene with molecular weight of more than 2.04 million was successfully prepared at polymerization reaction temperature of 70℃, polymerization time of 60min, with triisobutylaluminum as the promoters and P Donor as the external donor.