doi:10.16597/j.cnki.issn.1002-154x.2026.02.006
准确测定淤浆法聚乙烯黏均分子量方法的研究
张晟曦
(中国石化扬子石油化工有限公司, 南京 210048)
摘 要 淤浆法聚乙烯作为新型高性能材料,其黏均分子量是影响下游客户加工条件的关键指标。2025 年公司淤浆法聚乙烯装置建成开车后,所产产品黏均分子量在100 万~550 万之间,装置生产稳定后,为实现对产品分子量的持续监控,首先优化了现有毛细管测试法,建立了300 万黏均分子量级别的标准化测试体系。然而此方法对超高分子量(Mv>300 万)样品测试存在准确度低、重复性差、易导致毛细管堵塞等问题。引入压差法以实现大于300 万黏均分子量样品的精准测定,优化后,测试平行性好,RSD 小于3%,为装置稳定运行和品牌形象树立提供了可靠支撑。
关键词 淤浆法聚乙烯 黏均分子量 特性黏度 压差法
Improving the Accuracy of Viscosity-average Molecular Weight Determination for Slurry-process Polyethylene
ZHANG Shengxi
(Sinopec Yangzi Petrochemical Co., Ltd., Nanjing 210048, China)
Abstract Slurry-process polyethylene, as an emerging class of high-performance materials, exhibits viscosity-average molecular weight (Mv) as a pivotal parameter that critically governs the processing behavior and end-use performance for downstream clients. Upon successful commissioning of the company's slurry-phase polyethylene facility in 2025, the resultant products demonstrated Mv values spanning 1.0 × 106 to 5.5 × 106. To ensure robust, ongoing surveillance of molecular weight characteristics following attainment of steady-state operation, the conventional capillary viscometry protocol was initially refined, culminating in the establishment of a standardized, high-fidelity testing framework tailored specifically for the approximately 3 × 106 molecular weight regime. Notwithstanding these advancements, application of the optimized capillary method to ultra-high molecular weight specimens (Mv > 3 × 106) revealed persistent limitations, including compromised measurement accuracy, inadequate repeatability, and recurrent capillary occlusion attributable to the extreme solution viscosities. To circumvent these constraints, a differential pressure viscometry technique was subsequently implemented and rigorously optimized for precise quantification of samples exceeding 3×106 in Mv. Post-optimization, the methodology exhibited superior intra-assay precision, with relative standard deviation (RSD) consistently below 3%. This enhanced analytical capability furnishes reliable technical assurance for sustained process stability, consistent product quality, and the reinforcement of brand integrity within the high-performance polyethylene sector.
Keywords slurry-process polyethylene viscosity-average molecular weight intrinsic viscosity differential pressure method