Abstract: 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.

Key words: UHMWPE; blending modification; degradation-rheological behavior; viscous fluid activation energy; structural viscosity index