Loop Length of Plain Single Weft Knitted Structure with Elastane

For decades, scientists have been trying to define relationships among yarn parameters, knitted fabric parameters, and knitting parameters with loop models. Recently, the geometrical loop models have returned to focus as they assist finding the effective parameters which cause dimensional changes during relaxation. Furthermore, they help designing knitted structures for technical applications and obtaining computer simulations of knitted structures. In the past, geometrical loop models considered more or less porous structures and the yarns used were mostly conventional, without elastane. The behavior and characteristics of compact knitted fabrics made from elasticized yarns have been investigated only recently. In general, mostly the structures with plated elastane threads have been analyzed. The aim of the research was to study the geometrical parameters (yarn thickness, loop width, loop height, fabric thickness, loop length) of plain single weft knitted structures made from various elasticized yarns, in comparison to equivalent structures made from conventional yarns. In the study, the most frequently applied loop models for the loop length calculations were evaluated with the emphasis on their adequacy for elasticized knitted structures. A new loop model for an elasticized weft knitted structure based on the multiple linear regressions was defined. INTRODUCTION As early as in the first half of the 20 century, scientists tried to define relationships among yarn parameters, knitted fabric parameters and knitting process parameters with loop models. The first loop models dealing with the single knitted structure were geometrical and relatively simple [1–3], and they only approximately corresponded to the yarns and knitted structures applied at that time. The subsequent models were more complex [4–11], and played an important role in the control of knitted fabric dimensions and mass per unit area. Later on, loop models [12–16] were designed for graphic simulations and knitted structure planning. Supported by the latest expertise, testing and measuring techniques, e.g. electron microscopy [13,14] and computer aided image analysis [15], loop models enabled a more precise specification of the loop shape and size, depending on the geometrical parameters of the loop. Contemporary computer graphics have been lately used to additionally illustrate the knitted loop geometry [16,17]. In addition to mechanical and energy loop models, which interpret the behavior of knitted structures under loading, the geometrical loop models have recently returned to focus. Geometrical loop models assist finding the effective parameters which cause dimensional changes during relaxation, enable planning the production of a piece of fabric before knitting, assist designing knitted structures for technical applications, obtain computer simulations of knitted structures for design or fault-assessing purposes, help creating a physical loop model, help evaluating curling etc [17]. Due to the three-dimensional curved shape of the loop, knitted structures are generally more porous and extensible than other textile structures. On the other hand, contemporary knitted fabrics with incorporated elastane usually exhibit a very compact structure due to extensive shrinking relaxation after knitting, wet finishing and care processes. In the past, various geometrical loop models considered more or less porous structures, e.g. open, normal and to a certain degree also closed (compact) structures [2–10,12]; however, the yarns used were mostly conventional, i.e. without elastane. The behavior and characteristics of compact knitted fabrics made from elasticized yarns have not been investigated until recently [18– 21]. In general, mostly the structures with plated elastane threads have been analyzed [22–24]. The aim of the presented investigation was to study the geometrical parameters (yarn thickness, loop width, loop height, fabric thickness, and loop length) of plain single weft knitted structures made from various elasticized yarns, in comparison to equivalent structures made from conventional yarns. One of the