Improved solution stability and spinnabilitiy of concentrated polyaniline solutions by using DMPU solvent

Summary form only given. It is widely known that polyaniline base is soluble in N-methyl-2-pyrrolidinone (NMP). However, concentrated polyaniline solutions (> 5%) in NMP were recently reported to be highly unstable, forming gels readily at room temperatures. It is found that the solution stability of polyaniline is significantly improved by using N,N'-dimethyl propylene urea (DMPU) as the solvent. In this paper, the solution stabilities and fiber spinnabilities of polyaniline solutions in NMP, DMPU, and LiCL/NMP (0.5 wt% LiCL) are studied and compared by using a cone-and-plate rheometer and wet-spinning processing, respectively. The polyanfline solution in DMPU showed remarkably improved stabilities, e.g. a 20 wt% polyanitine/DMPU solution did not form a gel in a period of 12 hours while a 20 wt% polyaniline/NMP solution formed a gel within a few minutes. All examined polyaniline solutions showed a similar trend in rheological behavior in that the viscosities become more shear-dependent with either increasing concentrations or increasing aging time. The spinnability of polyaniline solutions was also improved by using DMPU as the solvent. The results of these studies and the rheological parameters necessary for successful wet spinning of polyaniline fiber will be discussed.