Viscoelastic Properties for Physical Gelation of Polyacrylonitrile Solution induced by Freezing – Thawing Method

Polyacrylonitrile (PAN) gel was prepared by the freezing and thawing method using the solvents of N,N-dimethylacetamide (DMA) and tetramethylene sulfone(sulfolane). The gelation time after a series of freezing and thawing was examined with varying PAN concentration of DMA solution and the freezing time. Dynamic viscoelasticity was measured in the course of gelation for DMA solution to observe the intermediate state called as the critical gel. Double endothermic peaks appeared in the heating DSC scans for gels prepared from sulfolane solutions.