On-Line BirefringenceAn Olympus polarizing light microscope was used to investigate the birefringence of vertical filament from CAB /DMA solutions of various concentrations. These were extruded vertically downward from the Harvard infusion withdrawal pump used in the wet spinning studies. There was no takeup and the filaments descended under gravity. These studies were similar to the experiments reported by Onogi et al.5
Wet SpinningThe wet spun fibers were produced using a dry jet method of the type introduced by Blades'* for liquid crystalline solutions of p-linked aromatic polyamides. The wet spinning apparatus used was essentially that of Hancock, Spruiell, and White, which was described in an earlier paper.15
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