Viscoelastic Behavior of Polyacrylonitrile/Dimethyl Sulfoxide Concentrated Solution with Water

The spinnability and polydispersity of polyacrylonitrile/dimethyl sulfoxide (PAN/DMSO)/H2O spinning solutions with conventional PAN molecular weight and comparative high PAN concentration have been investigated using a cone-plate rheometer. It is observed from the measurements that, the viscosities of the solutions decreased with the rising of shear rate, and then stabilized to almost the same value, regardless of the PAN concentration. The chain orientation in the fiber formed under constant shear rate cannot be changed considerably even after long relaxation of more than 900s. For dynamic experiments, a steady increase of both G' and G '' with escalating oscillation frequency was seen for all samples. Higher viscous-elastic modulus at higher H2O content was found, too. It is also concluded from the log G' - log G '' plot and the gel point that the PAN/DMSO/H2O system with regular PAN molecular weight behaves very close to a mono-disperse system, thus very suitable for gel spinning and for preparation of high performance PAN precursor fiber. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1437-1442, 2009