spun yarns
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A novel concept of producing false-twist yarns by cyclical stress fluctuation was developed. The forming principle was introduced to analyze the formation process of false twists on rotary threaded contact surfaces. Geometric analysis indicates that cyclical stress variations produce extra rotations (false twists) on fiber strands in the yarn formation area, causing twist redistribution and fiber arrangement remodeling with the appearance of local fiber reversion. Theoretical analysis reveals that more false twists are produced when the spun yarn is in contact with surfaces of high traverse speeds. Then, a motion simulation model using different traverse speeds of the threaded contact surface was established to compare the yarn internal stress variation, verifying the false-twist efficiency at different traverse speeds. Finally, a systematic comparison was conducted between the yarns spun at different traverse speeds. It was shown that the yarn properties improved with higher traverse speeds of the threaded contact surface, achieving less hairiness, high yarn strength, and low residual torque.

Abstract To take the advantages of spun yarns such as porosity, softness, bending as well as usability as yarn/fabric forms, in this study, it was worked on an alternative conductive yarn production method. Different from other methods such as coating, core-spun, blending, a conductive nanosuspension was applied to viscose, cotton and polyester open fibre bundles with different feeding amounts during the ring spinning with a specially developed apparatus. Reduced graphene oxide (rGO) was used to impart conductivity. Different from literature, rGO was synthesized with a single step process instead of two-step processes to ensure simple, easy-to-apply process and industrial applicability. Following to yarn production, winding, knitting and washing processes were realized to evaluate the changes in yarn conductivity and the usability of the yarns in the post-spinning processes. In addition to tensile properties of the yarns and air permeability of the fabrics, electrical resistance and environmental impact of the method was compared with immersion&drying process. The results indicated that alternative method allows the production of conductive (lower resistance than 100 kΩ) but also stronger, flexible, washable and breathable electronic textile products with an environmentally friendly process. There has been no effort, as yet, to get conductivity in this manner. Therefore, the developed method can be considered to be a new application in the functional yarn production field. The produced conductive yarns can be converted into fabric form by weaving, knitting and embroidery. Therefore, they can also be seen as an ideal as the platforms for future wearable electronics.

Yarn quality influences both fabric production processes efficiency and export market. One method used to gauge competitiveness of an industry is to study its product quality. The aim of this research work is to evaluate the quality of Ethiopian textile spinning mills’ 100% cotton carded ring spun yarns in terms of its evenness (coefficient of mass variation, CVm), imperfections (thick and thin places, neps), and tensile properties with USTER Statistics 2018. Five spinning mills (B3, A0, A2, A4, and K3) of 15N, 20Ne, 25Ne, 30Ne, 35Ne, and 40Ne nominal yarn counts have been selected for the study. The yarn evenness and imperfections were measured using USTER tester 5 and tensile using a STATIMAT tester. The USTER statistical results showed 20.3Ne (mill B3), 32Ne (mill A4), and 36.2Ne (mill A2) had better overall quality, respectively. It was observed that most selected spinning mills had low evenness, imperfections, yarn strength, and good yarn elongation. Tensile properties of A2 (32.85Ne and 36.2Ne) had fallen under 5% USTER statistics percentile which indicates excellent yarn strength. Generally, from studied mills, it was seen that 61.5% of cotton yarn CVm and thin places falls at above 95% and 15% of yarn tenacity falls at ≤5% of Uster statistical percentile.

Abstract Strain sensing is one of the important functions of intelligent fabric, which can transform the external stress (or strain) into visible electrical signals and monitor the characteristics of human physiology and motion. At present, the flexible strain sensor has low sensitivity, small strain range and unstable performance after repeated stretching. In this work, core-spun yarns with polyurethane (PU) filament as core and long silver nanowires (AgNWs) loaded cotton fiber as shell was fabricated by spinning technology. The results showed that when the loading of AgNWs was 10 wt%, the strain range of the PU/cotton@AgNWs core-spun yarn was 0-60%, the gauge factor of 12.6 was linear, and the strain sensing and mechanical properties were stable after repeated stretching. This strain sensing elastic core-spun yarns constructed by spinning technology could be used as one of the important materials for intelligent wearable devices.

In order to explore the differences between conventional and dual-feed-opening rotor spinning units (RSUs), this work compares the airflow characteristics of two RSU models utilizing a computational fluid dynamics simulation model with the accuracy verified by airflow behavior observation and air pressure measurement. The effect of two different opening roller speeds on the airflow field distribution of a dual-feed-opening model is also investigated. In addition, the yarn properties of six pure and blended yarns corresponding to the two RSU models are evaluated. The results reveal that the distributions of airflow velocity vector and air pressure in the two RSU models show a strong similarity under the same boundary conditions. However, the dual-feed-opening model possesses a centrosymmetric and more balanced airflow field distribution compared to the conventional model. In addition, the dual-feed-opening yarns show a superior performance in comparison to the conventional yarns. Furthermore, for the dual-feed-opening model, there are equivalent contributions of two separated opening and fiber transmission systems to the airflow field distribution and yarn formation. Compared to the configuration with the same two opening roller speeds, the dual-feed-opening model configured with two different opening roller speeds obtains an improved blended yarn performance with having few effects on the airflow characteristics. This strength of the dual-feed-opening RSU could facilitate the production of blended and fancy yarns employing the fibers with diverse properties. This study could provide some guidelines for the manufacture of rotor-spun yarns and the future design of RSUs.

The uses of recycled materials have gained massive importance in the textile sector and other application areas as the effects of reducing natural resources are felt worldwide. This study aimed to analyze the effects of recycled fiber usage on the properties of OE-rotor spun yarns and hand-woven fabrics produced from these yarns. For this purpose, OE-rotor yarns are produced at different proportion levels from virgin cotton and recycled fibers derived from knitted garment wastes at 25%, 50%, and 75%, respectively. For a better assessment, properties of OE-rotor yarns that contain recycled fibers and 100% virgin cotton OE-rotor yarns are compared. Physical, structural, and mechanical properties such as unevenness, imperfections, hairiness, breaking force, and elongation are analyzed by Uster Tester 5 SX, Uster Zweigle Hairiness Tester 5, and Uster Tensorapid 3. Plain and twill hand-woven fabrics are produced from OE-rotor spun yarns. Effects of recycled fiber proportion on hand-woven fabric properties such as pilling, abrasion resistance, and air permeability were also evaluated. Results showed that the use of up to 75% of recycled fiber cotton blended yarns shows no statistically significant differences in yarn and fabric properties.

This article presents a systematic investigation of the knitted fabrics made from various blends of intrinsically antimicrobial poly (hydroxybutyrate-co-hydroxyvalerate)/polylactide acid filaments and cotton staple fibers. The effects of blend yarn, fabric structures, and distributions of fibers on antimicrobial properties of resultant yarns and knitted fabrics were studied. The relationships among fiber distribution, blend ratio, and anti-microbial properties were experimentally determined for three blend yarns made by sirofil, wrap-spun, and core-spun spinning technologies. The fabrics made from the sirofil-spun and wrap-spun yarns show better anti-microbial effects against Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans than those of the core-spun yarns, according to the standard AATCC100-2012 Antibacterial Finishes on Textile Materials (American Association of Textile Chemists and Colorists, 2012). An alternative blending method of co-knitting of the pure poly (hydroxybutyrate-co-hydroxyvalerate)/polylactide acid yarns and cotton yarns achieved excellent antimicrobial effects. Furthermore, a wearing trial of underwear made from the blended knitted fabrics was conducted in a nursing home. The wearing comfort of the garments, low-stress mechanical and surface properties of fabrics were evaluated objectively by the Kawabata Evaluation System of Fabric (KESF) system and subjectively by a questionnaire survey to users.

Gradient colored yarns are manufactured by controlling the blending ratios of three-primary-colored fibers in a slight distribution of gradients along the yarn length, thereby resulting in a continuous natural variation in mixed colors of the fibers throughout the whole yarn. The spinning of gradient colored yarns still remains a challenge, which requires the reliance on digital blending theory of colored fibers and the supporting of multi-channel computer numerical control (CNC) spinning technique. This paper constructed a three-primary-colored fiber gridded color mixing model and its mass mixing matrix and color mixing chromatography matrix by mass discretization and coupling pairing with a 10% gradient for the three-primary-colored fibers. With the aim of continuous natural gradient of mixed colors, the blending ratio gradient path of three-primary-colored fibers was planned based on the mass mixing matrix, and a method of regulating the gradient of color difference between adjacent color segments was proposed. In order to realize the natural gradient of color of the forming yarn, the spinning mechanism of gradient colored yarn was established based on three-channel CNC spinning mechanism and the time-series yarn simulation model, and the time-series spinning processing parameters of three-channel CNC spinning machine were devised. Four gradient colored yarns with different gradient paths were designed and prepared, the linear density, twist, unevenness, surface hairiness, and tensile strength of the spun yarns were measured, compared, and analyzed, and knitted fabrics with color gradient effect were fabricated by small circular knitting machine to obtain continuous and natural color transition with a dreamy and mysterious color effect.