In recent years, there has been a substantial increase in the production of knitted fabrics with textured synthetic yarns in circular knitting machines. However, there are few studies for this type of yarn on the effects of variations in tension on circular knitting machines. In this work, we examine the variation in yarn tension before the positive feed and analyze its influence on the properties and quality of knitted fabrics produced with spun yarn and textured synthetic yarn. Knitted fabrics were produced with spun cotton yarn and textured microfiber nylon yarn (polyamide), which were analyzed with respect to loop length. The results demonstrate the importance of controlling the yarn feed tension when working with textured yarns, even with the use of a positive feed, in contrast to what occurs when spun yarn is used.

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VASCONCELOS, F. B. Influence of machine parameters on the physical properties of polyamide/elastane single jersey fabrics. 2012. 138 f. Dissertação (mestrado)-Escola de Artes, Ciências e Humanidades,

The study evaluates comparatively some physical and chemical properties of polyamide 6.6 standard and biodegradable. It also evaluates the period of biodegradation of the biodegradable yarn sample and standard sample. The physical properties analyzed were tensile strength, elongation, and tenacity. The chemical properties were related to the behavior of the samples in dyeing and the evaluation of subsequent strength dyeing. The evaluated samples were taken from knitwear produced with polyamide textured filament yarn 80 dtex f 68x1, standard and biodegradable, being purged, bleached, and dyed. The results of the physical tests, although statistically different, have values ​​very near the average, which in practice represent acceptable values ​​within the statistical control process. Both standard and biodegradable samples had the same chemical behavior and there is no difference. Concerning to biodegradation time under laboratory conditions, the carbon dioxide produced by the samples was monitored and measured to determine the percentage of biodegradation according to ASTM D 5511. After 735 days the percentage of biodegradation of the biodegradable yarn was 81.7% and of the normal yarn was 5.2%. This is an expressive gain in ecological terms for synthetic fiber.