Masamoto Watanabe

STUDIES ON THE INFLUENCE OF DRYING CONDITIONS ON FIBER PROPERTIES IN THE WET SPINNING OF ACRYLIC FIBER

An acrylic fiber, which is produced by wet spinning in the solvent-water coagulation system, is investigated in order to find out the influence of drying conditions on homogeneity in microstructure and mechanical properties of fiber. Mechanical properties of fiber can be changed by drying temperature and degree of relaxation. By drying in relaxed state, tensile strength of fiber changes a little, but tensile elongation and knot strength increases. Homogeneity in fiber microstructure increases by drying at high temperatures.

STUDIES ON THE RELATIONSHIP BETWEEN HEATSET CONDITIONS AND FIBER PROPERTIES IN THE WET SPINNING OF ACRYLIC FIBER

An acrylic fiber was investigated in order to find out the effects of steam and hot water treatment to mechanical properties of fiber.Mechanical properties of fiber vary by the degree of relaxation during drying or heat-set. Homogeneity in fiber-microstructure increases by steam or hot water treatment. Stress-strain behavior of fiber is susceptible to temperature.

STUDIES ON ACRYLIC FIBER

The wet spinning of dimethyl formamide solution of acrylonitrile copolymer into the glycerine bath was investigated. The results obtained on the effect of bath temperature are as follows.(1) The spinnability that is, maximum spinning velocity, increases with increasing bath temperature and increases with decreasing output and the viscosity of polymer solution.(2) Decrease of maximum draw ratio of undrawn filaments with increasing bath temperature is not particularly large.(3) The effect of bath temperature upon dry tensile strengths of drawn filaments varies with the draw ratio of these filaments. When the draw ratios of the filaments are small, the above mentioned effect is not distinct. On the other hand, when the draw ratio of the filament becomes larger, the lower the bath temperature, the larger the dry tensile strength. As to the dry tensile elongation, this effect is also not distinct.(4) As to the dry knot strength and elongation, the effect of the draw ratio is larger than that of the bath temperature.(5) The initial moduli and the toughnesses calculated from stress-strain curves of drawn filaments become larger with decreasing bath temperature, The similar results may be obtained for the elastic recovery characteristics.(6) At lower bath temperatures, the textures of filaments obtained by wet spinning become compact or dense as the desolvation or the diffusion of the solvent is comparatively slow. On the contrary, at elevated bath temperature, owing to the higher speed of desolvation, the contrast between skin and core become clearer, and it may be seen that there are many microscopic holes in the core zone.These differences in the texture of the filaments coinside with those results obtained from the specific gravities and ratios of the cross sections.