低缠结超高分子量聚乙烯树脂的制备及表征

Preparation and characterization of low entanglement ultra-high molecular weight polyethylene resin

摘要:

为解决传统Ziegler-Natta催化剂（简称Z-N催化剂）制备的超高分子量聚乙烯（UHMWPE）缠结程度较高、加工困难等问题，以MgCl2、TiCl4、异辛醇、正硅酸四乙酯（或邻苯二甲酸二己酯）为主要原料，采用化学反应法制备了负载型Z-N催化剂cat1（或cat2）。分别以cat1、cat2为主催化剂、三乙基铝为助催化剂，采用淤浆聚合工艺制备低缠结UHMWPE，测定了cat1、cat2的粒径分布和金属元素含量，考察了聚合温度、时间对催化剂催化活性和UHMWPE的黏均相对分子质量（Mv）的影响，并使用流变分析法和DSC热力学退火法对UHMWPE的缠结程度进行了表征。结果表明，制备的cat1、cat2与最初设计相符，在优化的淤浆聚合工艺下，聚合反应温度分别为65℃，70℃时，cat1、cat2催化活性分别达到27700、37700 g PE/g cat.，制备的UHMWPE的Mv分别为6.01×106、5.03×106，起始储能模量分别为0.21、0.13 MPa，缠结程度低于商品化UHMWPE。

Abstract:

In order to solve the problems of high entanglement and difficult processing of ultra-high molecular weight polyethylene (UHMWPE) prepared by traditional Ziegler Natta catalyst (Z-N catalyst), a magnesium dichloride supported Z-N catalyst cat1 (or cat2) was prepared by chemical reaction method using MgCl2, TiCl4, isooctanol, tetraethyl orthosilicate (or dihexyl phthalate) as the main raw materials.Low entanglement UHMWPE was prepared by slurry polymerization using cat1 and cat2 as the main catalysts and triethylaluminum as the co catalyst. The particle size distribution and metal element content of cat1 and cat2 were measured, and the effects of polymerization temperature and time on the catalytic activity of the catalyst and the viscosity relative molecular weight (Mv) of UHMWPE were investigated.The degree of entanglement of UHMWPE were characterized by rheological analysis and DSC thermodynamic annealing.The results showed that the prepared cat1 and cat2 were consistent with the initial design. Under the optimized slurry polymerization process, when the polymerization reaction temperature was 65 °C and 70 °C, the catalytic activity of cat1 and cat2 reached 27700 and 37700 g PE/g cat respectively. The Mv of the prepared UHMWPE was 6.01 × 106 and 5.03 × 106, and the initial storage modulus was 0.21 and 0.13 MPa respectively. The entanglement degree was lower than that of commercial UHMWPE.