Abstract: The rheological characteristics of unplasticized poly(vinyl chloride)（PVC-U）was evaluated by a torque rheometer. The resulting rheological torque curves indicated that PVC-U achieved a higher minimum torque with its gelation degree getting greater, thus, the difference between its maximum and minimum torques became smaller. On the basis of this relationship, an evaluation method was proposed for estimating the gelation degree of PVC-U.

Key words: poly(vinyl chloride), gelation degree, torque rheometer