This research studies the effect of extension increase percent of bare Lycra yarns during loop formation on the geometrical, physical and mechanical properties of plain jersey fabrics. Samples with 100% cotton yarns, Lycra yarns in alternating courses (half plating) and Lycra yarns in every course (full plating) were produced on a circular knitting machine. The two latter cases were produced at five different levels of Lycra extension. Thermal setting was carried out without any traverse tension during finishing, thus evaluating the full effect of Lycra extension. Results show a sharp increase in the courses density rather than the wales density. Fabric thickness and weight per unit area also increased, and air permeability in the case of the half and full plating fabrics decreased considerably. The breaking load and extension also increased, while the initial elasticity modulus decreased with an increase in abrasion resistance in the case of full plating. A comparison between half and full plating methods contributes to improving fabric quality by determining optimal Lycra percentage.

The scope of this research is to study the effect of yarn structure and yarn count on properties of types of core-spun yarns, including elastic core/T400, elastic core/Lycra, dual core, and tri-core yarns. Five types of yarn structures and three yarn counts were produced. Mechanical properties, yarn irregularity, imperfections, and hairiness were measured. Full-factorial analysis and Tukey tests were performed on the test results. It was concluded from factorial analysis that yarn count, yarn structure, and two-way interaction had a significant effect on yarn properties, except for yarn hairiness where the effect of yarn structure and two-way interaction was not significant. A Tukey pairwise comparison was used in this study to specify exactly the subgroups of yarn count and yarn structure that have a significant mean difference. The scanning electron microscopy (SEM) images of the dual-core yarns and tri-core yarns were performed to illustrate the structure of these yarns.

AbstractThis research aims to evaluate the properties of cotton single jersey knitted fabrics (SJKF) produced from cotton/spandex yarns at different Lycra states. So, four different SJKF were produced, namely 100% cotton, cotton with additional Lycra (full-platted), core, and dual-core-spun (DCS) yarns with the same loop length. The thermal comfort properties, fabric recovery, total hand value (THV), moisture management parameters, and air permeability were measured. The experimental results showed that the use of DCS yarns in the SJKF improves the fabric elastic recovery by 100%. The obtained values of air permeability, THV, and overall moisture management capacity of stretched SJKF are lower than 100% cotton fabric sample. Thermal absorptivity of core and dual-core samples increased by 27% and the water vapor permeability decreased by 18% compared to 100% cotton fabric sample.

This research aims to build a computer-based system for measuring slub yarn characteristics and evaluating the results using statistical methods. The measuring system was based on the electrical condenser of the Uster evenness tester as a measuring sensor. A digital storage oscilloscope was used to convert the analogue output signals into digital data to be recorded on a computer. A designed computer program was constructed using MatLab language for signal analysis based on a proposed method. Final results from this system contained graphical plots for the three measured slub yarn geometrical parameters slub length, slub distance, and slub thickness and a final report for all the measured slub yarn characteristics. The results of tested slub yarn samples showed that actual slub geometrical parameters differ from nominal values and the difference had two level: prevailing difference and outlier values. Outliers which are considered slub yarn defects were detected and counted in a final report using the box plot statistical method which could be an effective industrial tool for evaluation of both yarn quality and machine performance. The prevailing difference was assessed using histogram comparison which could help in adjusting the setting of slub yarn device to obtain the required appearance.

This work aims to compare the effects of different yarn structures on the elastic properties. A new type of elastic core-spun yarn which is called tri-core (elastane/T400/elastane) yarn is introduced and tested for elastic properties after cyclic loading. The other yarn structures used are single-core/T400, single-core/lycra, dual-core (elastane/T400) yarn, and yarn without a core component (conventional). The five types of yarn structure were produced at three levels of yarn counts (10, 14, and 18 Ne). Elastic properties after cyclic loading including stress decay, permanent deformation, elastic recovery, and relaxation rate were calculated and statistically analyzed using two-way analysis of variance. The scanning electron microscopy images of the five structures used were produced to illustrate the structure of these yarns. The results determined that elastane/T400/elastane core-spun and single-core/T400 yarns have higher values for most of the elastic properties. It was found that yarn count and yarn structure significantly affect stress decay, while the yarn structure significantly affects permanent deformation and elastic recovery. On the other hand, yarn count significantly affects the relaxation rate. Data showed that the number of cyclic tests significantly influences yarn elastic recovery.