Study On The Elasticity Of Polyurethane Warp Knitted Elastic Fabric

Polyurethane warp-knitted elastic fabrics is found favor in consumers’ eyes, and it couldsatisfy the needs of consumers with the good close fitting and shrinkage effect on bodies withthe market share increasing. There are three characteristics of the current production ofspandex tricot fabric, the application breadth, production efficiency and the quality ofinstability. This paper mainly studies the elastic properties of polyurethane tricot fabric and itsrelationship with differentiated production process settings. In order to promote theproduction and application of it, it will be of theoretical and practical significance to study theproduction process of Polyurethane warp-knitted elastic fabric as well as the extension andresilience. This topic is established in this context.Through the production practice of polyurethane warp-knitted fabric, it discusses the keypoints of its production process and summarizes the laws of its parameter setting in warping,knitting and finishing. It points out that the particularity of the polyurethane warp-knittedfabric technology is the stretch and shrink of spandex yarn and its fabric. Besides, spandexcontent is regarded as an important specification of fabric. In order to ensure the smoothprogress of production, spandex yarn linear density, warping and weaving spandex draft rate,the let-off amount of spandex bar is the important parameters to control spandex content.Through the study of the elastic mechanism of spandex and its fabric, it notes that therelationship between the tensile properties of warp knitted fabrics and the elastic property ofspandex. In accordance with ASTM D4954-2008, the test standard of elasticity,29differentstandard sizes spandex tricot cloth fabric are tested in this paper which is of different technicalparameters such as materials, machine number and density, in order to examine the effect ofdifferent technical parameters on the fabric elongation and recovery properties.By studying the effects of raw material on the elastic spandex fabric, it is concluded thatwith the line density of spandex grows, the elongation of fabric decreases and resilience withelastic modulus increases. So it will be better to choose spandex with thick density. Whenspandex is knitting with non-elastic yarn such as nylon and polyester, the elongation ofnylon/spandex fabric is a bit better than polyester/spandex fabric. This is because these twomaterials result in differences in their elasticity, so in the actual production, the let-offamount of polyurethane can be adjusted so that the elastic polyester is improved.By the research warp knitting process parameters on the effect of polyurethane elasticfabric, it is found in the fabric structure, it is easy to change for the velvet flat spandex fabricon the vertical deformation. On the gauge of machine, the vertical elastic elongation of fabricincreases when the gauge of machine is rising. There is no significant change in the lateraldirection. The elastic modulus increases with fabric density, while elastic elongationdecreases. For the nylon/spandex which produces from the warp knitting machine of E36.And it find that when the spandex content of is18.9%, the elongation of the longitudinal andtransverse satisfies the required demand of garment which ranges from100%to180%.