Assessment of the influence of stitching on the tensile stress relaxation of laminated fabrics

Different parts of the garment may be laminated with an interlining in order to obtain specific appearance and form. Mechanical properties of the laminated fabric is affected by the properties of interlining and differs from the face fabric. Moreover, the existence of seam for joining the laminated fabrics in various parts of the garment is another issue, which has to be considered during the evaluation of the mechanical behavior of garment. Garments’ time dependent mechanical behavior such as the tensile stress relaxation is of great importance while wearing them. In this study, the tensile properties and the stress relaxation of a group of woven fabric, which was laminated by a nylon interlining, were investigated at two strain levels, before and after stitching. In this regard, the effects of strain level, lamination process, seam type and the stitch length were evaluated. According to the results, it can be declared that increasing the strain level reduces the stress relaxation percentage. The laminated fabric presented higher values of tensile stress and strain, while lower stress relaxation was occurred in this structure compared to the un-laminated fabric. Analysis of results showed that higher stress relaxation was obtained for the “stitched laminated fabric” compared to the “laminated fabric without seam.” Overall, in the presence of seam, the stress relaxation is affected by the seam type and the stitch length. Finally, the best correlation between the experimental stress relaxation results and the viscoelastic models were obtained for the two-component Maxwell model. The result of this study should be considered in designing and manufacturing of protective textiles and clothing that include both lamination and stitching processes and during use may be encountered with constant strains for a period of time.