Abstract
Generally, the conventional concentration of dry spinning solution is about 30% polymer, so the effects of the higher concentration of polymer solution than 30% was investigated.
By preparation of the high concentration of polymer solution, the spinning speed which governed the productivity was increased but the maximum spinning draft which represented the spinnability was decreased. These results are explained by the formation of the solidified surface which occurs by the rapid solvent evaporation in the immediate vicinity of the spinneret. Indeed, the structural difference between the skin and the core in the cross section could be observed optically.
The rate of shrinkage of fiber in spinning cell is affected by both the concentration of spinning solution and the drying condition. In consideration of the rate of shrinkage of fiber in spinning cell, the rate of extension which was the ratio of the spinning speed to the minimum spinning speed (the fiber travels down the spinning cell by gravity alone) was calculated. It was recognized that the stretchability depends upon this calculated rate of extention, although the stretchability is almost indepent of the spinning draft. Also, according to the observation of the cross section of the non extended fiber, the above mentioned structural difference is the cross section could not be observed.
The tenacity or the elongation of fiber is not affected by the concentration of spinning solution.
