The influence of structural variations on wool fabrics air permeability

Woven fabrics are materials of a sophisticated structure. Basic structural parameters, the raw material, linear density of warp and weft yarn, number of yarn twist, warp and weft density, warp and weft crimp, as well as weave contribute to the obtained properties of the fabric. Certain basic parameters of the fabric can be controlled directly either during the preparatory processes or during the weaving process itself. There are some important structural parameters, however, for which no direct quan¬titative controls exist. Since all structural parameters are closely interdependent, the lack of direct control results in an imperfect control of the fabric structure. The subject of the investigation was how small variations in semi-worsted wool fabric constructional parameters influence the air permeability, and to which extent they can be controlled in the design process and weaving of fabrics. The experiment showed that yarn count, warp and weft density and warp and weft crimp are highly interrelated, leading to small variations in the fixed sett. The sta¬tistical significance of small variations in the groups of fabrics was confirmed by the analysis of variance. The analysis confirmed that there were no differences in mass, although all other structural parameters differed. Additionally, a post-hoc Bon¬ferroni test showed that the structural parameters of the group of fabrics, which has a practically balanced structure, are always different to those of groups g2 and g3. Fabric alternations done on the same warp, in such a manner to achieve the same mass per square meter, showed that the change in weft yarn count and weft density influenced the fabric structure as a result of the crimp interchange. However, there was not a statistically significant difference among the three groups of fabrics when tested for air permeability