Study On Tearing Strength And Flame-retardant Properties Of PSA Fabric

Polysulfonamide fiber(PSA) is our self-developed high-performance fibers, which supplies a gap in the 250℃temperature resistant grades in synthetic fibers area.Compared with other similar products,PSA has excellent high temperature resistance performance,flame-retardant properties,easy dyeing properties,but the fatal shortcomings of PSA is the low fiber strength.Now the researchers are trying to improve the fiber strength by changing the spinning methods and processes.Low strength of fiber will result in the low mechanical properties of fabric, especially for the tearing strength of fabdc,which limits the use of homemade aromatic polysulfonamide fiber(PSA) in high performance fire-proof fabrics.In national standard GA10-2002,it regulates that the tearing strength of the fabric for firefighters protective clothing must be not less than 100N.However,the current PSA fabric's tearing strength is far away to the standard requirement. Some effective work is having been done by researchers in TANLON Ltd.to improve the tear strength of the PSA fabric. In this paper,the tearing strength of fabric was eventually improved to achieve the standard requirements by changing the fabric structure,blending with suitable high-strength fibers and processing soft finishing for the fabric, without changing the existing spinning method and process conditions.In early studies,the damage length was used as an index to characterize the PSA flame retardant fabrics and only single-factor of the influence on the damage length was analyzed.However,in this paper,the effect of multi-factor on the damage length was considered and the foremost factor was obtained. Damage length can only be used to characterize the flame retardant fabric from the one-dimensional length,while damage area can represent from two-dimensional space.However,there is no national standard for testing damage area at present.Two methods for testing this index were developed in the paper.Main research contents and results are as follows:(1) Improvement the tearing strength of PSA fabricDue to the tearing strength of the raw PSA sample is far less than 100N,it was improved by increasing the warp and weft density of fabric,blending with 5%Kevlar and 10%PBO high-strength fiber.The trapezoid tear method was used to evaluate the tearing strength of the fabric samples,and the results were found that warp and weft densities had no significant effect on fabric tearing strength,while high-strength fiber blend can effectively improve tearing strength,but can not reach the standard requirements yet.The process of soft finishing for PSA fabric was further applied to improve the tearing strength.The results showed that the breaking extension of the PSA fabric was obviously increased after soft finishing,indicating the tearing performance was improved.The basket-weave PSA fabric with blending 5% Kevlar high-strength fiber met the standard requirements.(2) Study on the flame-retardant properties of PSA fabricVertical flammability test was used to evaluate the PSA fabric with different composition,weight,thickness,dyeing.The results showed that there was no afterflame time,afterglow time or melting & dripping observed in all samples and the PSA fabrics blending with flame-retardant fibers presented much better apparent performance than that without blending.Moreover,the flame-retardant property was visibly decreased after dyeing and enhanced as the increasing of the fabric weight,thickness.(3) Methods for testing damage areaThe damage area was tested by weigh and image methods.Results revealed that the damage area measured by image was a little larger than weigh method.They were well fitted with the damage length obtained according to the national standard testing method,which indicated that these two methods were effective.In this paper,the tearing strength of PSA fabric was improved and achieved the standard requirements by a series of measures.The influencing factors on the flame-retardant properties were analyzed and two methods for damage area testing were developed.It will have some practical significance for guiding the production.