| Polysulfonamide (PSA), our own-patented synthetic fiber, has good performance of heat resistance, thermal stabilization and fire resistance. And it has filled up the blank of thermal resistance fiber that can resist the temperature above 250℃in China. The excellent properties of PSA fiber in thermal properties, electrical behavior and chemical resistance endow itself with a bright market prospect in the field of industrial textiles. But we cannot spin smoothly because of the features of PSA fibers include higher volume specific resistance (VSR) and initial modulus, smaller surface friction coefficient, and the final yarns are more hairy and weak.The paper was written mainly concerned on the fiber pretreatment and spinning methods in order to improve the spinnability and the use value of PSA fibers.On the one side, the main purpose of fiber pretreatment is to increase the surface friction coefficient and then the holding force between fibers in the spinning process improved without obvious change of fibers'breaking strength. The two projects adopted here are plasma and alkali (NaOH) solution treatments, the optimum conditions chosen is put into use to the PSA fibers pretreatment, the differences between fibers with and without pretreatment in the spinning process and the final yarns quality are compared and analyzed. On the other side, The yarns were spun by Sirospun, Sirofil, compact spinning and traditional ring spinning, and the properties of these yarns were compared. The reasons for improvement in the yarn strength and reduction of the hairiness of the PSA yarn spun by the new ring spinning were analyzed. It would provide an important theoretical guideline for the application of these kinds of spinning in PSA fibers.The result showed that under the experimental conditions, the atmospheric plasma processing made little effect on fibers'elongation and breaking strength, and the static friction coefficient increased obviously by 22.5%-61.6%as the time extended. PSA fiber treated with NaOH solution, the treatment temperature had the greatest impact on fiber strength and elongation, while the bath ratio influenced the friction coefficient greater. On certain conditions, the two treatment options can improve the fiber surface friction coefficient without obvious reduction of the fiber strength and elongation. Due to the industrialization problem of plasma equipment treating mass fibers, this subject only gave a preliminary discuss and selected pre-alkali treatment as the final option for PSA spinning pretreatment method. The final treatment options:NaOH concentration 20g/L, bath ratio 1:20, temperature 80℃, time 50min. After alkali treatment, the PSA spinning process went smoother than the untreated fiber spinning, and the slivers'fluffy performance was controlled, the yarn breaking strength increased by 6.4%, the total hairiness longer than 3mm decreased by 9.5%, and the evenness CV (%) decreased from 13.71 to 12.13.The performances of the PSA yarns made from the same roving and different spinning methods were tested, the results showed that Sirospun, Sirofil and compact spinning all improved the quality of the final yarn effectively. Under the experimental condition in this paper, compared to the traditional ring spinning method, the three new ring spinning methods can improve the yarn breaking strength by 8%,4.5% and 9.9% separately; harmful hairiness longer than 3mm was reduced by 43.7%,46.9 and 30.9% respectively; the yarn evenness CV (%) also improved, and especially for Sirofil spinning the CV (%) decreased from 13.71 down to 10.11. Further study to confirm the influence of different filament pre-tension on Sirofil yarn quality, the study found that, with the increase of filament yarn pre-tension, the yarn strength first increased and then decreased, and when the pre-tension was 7cN, it reached the maximum, which increased by 12.5% to the traditional ring spinning yarn.This conclusion would provide certain theoretical direction for the optimal using of PSA fibers.
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