熔纺改性UHMWPE热降解流变行为研究

Study on Thermal Degradation-rheological Behavior of Modified UHMWPE

文章用烯烃类改性剂PO1对超高分子量聚乙烯(UHMWPE)进行共混改性以提高后者的熔融可纺性,采用Rosand RH-7型毛细管流变仪模拟熔纺热加工过程,研究了改性后体系的热降解流变行为。结果表明:UHMWPE/PO1体系在停留时间为15 min以下时,改性体系的热降解不明显,大于20 min后热降解明显,并伴随着热氧降解;改性后UHMWPE体系属于假塑性流体,但即使经历较长停留时间并在较高剪切速率下,体系的表观黏度仍然较高(大于100 Pa·s);体系的黏流活化能数值较低且随着停留时间的增加而增加,最大值仅有20.16 kJ/(mol·K);体系的结构黏度指数△η随温度及停留时间的增加呈降低趋势。

UHMWPE was modified by blending with olefin modifier PO1 to improve its melt spinnability. Thermal degradation-rheological behavior of modified UHMWPE system was studied by using Rosand RH-7 capillary rheometer. Results showed that thermal degradation was not obvious when the processing time was less than 15 minutes. However, thermal degradation began to become evident after treatment time was longer than 20 minutes and was accompanied by thermal oxygen degradation. The modified system showed a typical pseudoplastic flow behavior. Even after a long period of heat treatment and tested at a high shear rate, the apparent viscosity of the melt-system was still greater than 100 Pa·s. The viscous fluid flow activation energy of the system was low and increasing with the increase of treatment time. The structural viscosity index of the system decreased with increasing of process temperature and residence time.