Hemijska industrija 2006 Volume 60, Issue 5-6, Pages: 129-137
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Compressional behavior of knitted fabrics exposed to repeated wash and wear cycles

Stanković Snežana B.

The quality requirements of knitted fabrics nowadays have become highly demanding in terms of appearance and comfort properties. It is well known that yarns are subjected to tension, bending, torsion and compression during the wear and care of apparels. The appropriate selection of raw materials could be the way to reduce the deformation of knits caused by mechanical forces. Keeping in mind the fact that natural fibers and man-made fibers can significantly differ in respect to elastic properties, natural fiber and synthetic fiber knits were produced for the experiment. The experimental material included three different variants of knitted fabrics: 100% hemp knit, 100% PAC knit and hemp 50%/PAC 50% knit. The behavior of knitted fabrics during the relaxation of compression was investigated. In order to indicate the change of the compressional properties of knitted fabrics, the same investigation after undergoing repeated wash and wear cycles (during eight weeks) was repeated. Although the structure of the tested samples was the same, there were differences in the compressional behavior of the knitted fabrics. It is obvious that the differences in the elastic properties of hemp and PAC fibers were projected into the knits. Compression curves were drawn in order to obtain an insight into the change of the compressional behavior of knitted fabrics during wear. These curves also enabled a comparative estimation of the compressional behavior of knits made of different yarn components. The surfaces proportional to the work of the compression for each of the cycles, as well as the work of compression between the first and the fifth cycles, of loading-unloading cycles were calculated. In order to compare the tested knitted fabrics, the hysteresis of compression was analyzed from the aspect of ability of elastic recovery. The change in compressional behavior of knits exposed to wear and care cycles was confirmed. However, analysis of the comparative compression behavior of knits before and after wear, indicated differences between the tested samples. The mechanical model for the lateral compression of fabrics derived from van Wyk's compression law, which explains the relationship between the pressure and volume of a fiber mass during compression is well known in the literature. In order to obtain a comprehensive insight into the compressional behavior of knitted fabrics, the results obtained were approximated with van Wyk'a equation.

Keywords: hemp, PAC, knitted fabric, compressibility, elastic recovery, compression hysteresis, van Wyk's compression low

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