The rheological behaviour of different PVC resins between 160℃and 200℃ have been studied

their changes in morphology were observed by scanning electron microscopy.The relation of η'-I/T of PVC with different morphology shows the existence of a transition in flow mechanism at 190℃

morphological photographs of scanning electron microscopy gave direct evidence in following sequence: -1μ primary particles and their agglomerates are main flow units in PVC below 190℃

but - 0.05 ℃ sub-primary particles are the flow units in PVC above 190℃and ～0.05μ sub-primary particles are alrea-dy main structural morphology at 190℃.n'increases with temperature when sub-primary pa-rticles are the flow units in PVC.