Abstract
Thermally induced gelation of polyacrylonitrile(PAN) solution in dimethylacetamide was studied through dynamic viscoelasticity measurements. PAN gel were prepared by the freezing(–50°C) and thawing(25°C) method. The evolution of G'(ω) and G"(ω) data in the process of gelation is observed and the critical behaviour is obtained around the sol-gel threshold in which the power law of G'(ω)～G"(ω)∝ωn holds. The evolution in the gelation can be interpreted through the dynamic viscosity, in which characteristic frequency window is defined in connection with the formation of PAN network. The relation between the frequency and the correlation length is also found. The correlation length characterise the size of the cluster formed by the aggregation of PAN chain in pre-gel state, and also characterise the size of regions within the network to follow the power law.
