Textiles, Volume 3, Issue 3 (September 2023) – 6 articles

In this work, two commercial extruded filaments for 3D printing obtained from different NatureWorks PLA resins (Ingeo™ Biopolymer 3D850 and Ingeo™ Biopolymer 4043D) were solid-state drawn at varying temperatures and subsequently heat treated by annealing. The aim was to analyze the effect of post-processing of industrial fibers (solid-state drawing and annealing treatment) with varied composition (PLA grades with different contents of D-isomer) on the mechanical performance and thermal stability of the obtained PLA fibers. Morphological, thermal, and mechanical characterizations were performed for the undrawn filaments and drawn fibers, both before and after heat treatment. Drawn fibers presented a fibrillar core–shell structure, and their mechanical properties were greatly improved with respect to undrawn filaments in accordance with their higher crystallinity. The resin with the higher content of D-isomer (4043D) resulted in lower crystallinities with a subsequent decrease in mechanical properties. After heat treatment, drawn fibers exhibited completely different behaviors depending on the PLA resin, with 3D850 fibers being much more stable than 4043D fibers, which underwent molecular orientation upon drawing rather than crystallization. The solid-state drawn fibers obtained herein are comparable to commercial fibers in terms of mechanical properties. Full article

Quick drying is one of the most crucial factors in the comfort and performance of active sportswear clothing. It helps to keep the wearer dry and comfortable by effectively wicking away sweat and moisture from the body. In the light of this, a substantial number of previous researchers have identified fabric properties and types that have a significant impact on fabric drying performance. Studies have also been conducted to examine the impact of fabric drying on human physiology during sports-related activities. However, there are still some technical knowledge gaps in the existing literature related to the drying performance of active sportswear fabrics. This review article provides a critical analysis of the literature on the impact of various fabric attributes as well as the physiological and environmental factors on moisture management and drying performance. The key issues in this field are determined so that future research can be directed and this scientific field can advance in order to improve the overall performance of active sportswear fabrics. Full article

Warp knitting is a highly productive textile manufacturing process and method of choice for many products. With the current generation of machines running up to 4400 min⁻¹, dynamics become a limit for the production. Resonance effects of yarn-guiding elements and oscillations of the yarn lead to load peaks, resulting in breakage or mismatches. This limits material choice to highly elastic materials for high speeds, which compensate for these effects through their intrinsic properties. To allow the processing of high-performance fibers, a better understanding of the viscoelastic yarn behavior is necessary. The present paper shows a method to achieve this in longitudinal yarn direction using a dynamic mechanical analysis approach. Samples of high tenacity polyester and aramid are investigated. The test setup resembles the warp knitting process in terms of similar geometrical conditions, pre-loads, and occurring frequencies. By recording the mechanical load resulting from an applied strain, it is possible to calculate the phase shift and the dissipation factor, which is a key indicator for the damping behavior. It shows that the dissipation factor rises with rising frequency. The results allow for a simulation of the warp knitting process, including a detailed yarn model and representation of stitch-formation process. Full article

With the development of smart and multi-functional textiles, conductive yarns are widely used in textiles. Conductive yarns can be incorporated into fabrics with traditional textile techniques, such as weaving, knitting and sewing. The electromechanical properties of conductive yarns are very different from conventional yarns, and they also affect the processability during end-product manufacturing processes. However, systematic evaluation of the electromechanical properties of commercial conductive yarns is still elusive. Different conductive materials and production methods for making conductive yarns lead to diverse electromechanical properties. In this work, three types of conductive yarn with different conductive materials and yarn structures were selected for electromechanical characterization. A total of 15 different yarns were analyzed. In addition, the change of resistance with strain was tested to simulate and predict the possible changes in electrical properties of the yarn during weaving, knitting, sewing and other end uses. It was found that Metal-based yarns have good electrical properties but poor mechanical properties. The mechanical properties of Metal-coated yarns are similar to conventional yarns, but their electrical properties are relatively poor. The data shown in this research is instructive for the subsequent processing (weaving, knitting, sewing, etc.) of yarns. Full article

Cotton contamination by honeydew is considered one of the significant problems for quality in textiles as it causes stickiness during manufacturing. Therefore, millions of dollars in losses are attributed to honeydew contamination each year. This work presents the use of UV hyperspectral imaging (225–300 nm) to characterize honeydew contamination on raw cotton samples. As reference samples, cotton samples were soaked in solutions containing sugar and proteins at different concentrations to mimic honeydew. Multivariate techniques such as a principal component analysis (PCA) and partial least squares regression (PLS-R) were used to predict and classify the amount of honeydew at each pixel of a hyperspectral image of raw cotton samples. The results show that the PCA model was able to differentiate cotton samples based on their sugar concentrations. The first two principal components (PCs) explain nearly 91.0% of the total variance. A PLS-R model was built, showing a performance with a coefficient of determination for the validation (R²_cv) = 0.91 and root mean square error of cross-validation (RMSECV) = 0.036 g. This PLS-R model was able to predict the honeydew content in grams on raw cotton samples for each pixel. In conclusion, UV hyperspectral imaging, in combination with multivariate data analysis, shows high potential for quality control in textiles. Full article

Auxetic metamaterials expand transversely when stretched longitudinally or contract transversely when compressed, resulting in a negative Poisson’s ratio (NPR). Auxetic fabrics are 3D textile metamaterials possessing a unique geometry that can generate an auxetic response with respect to tension. In weft-knitted auxetic fabrics, the NPR property is achieved due to the inherent curling effect of the face and back stitches of the knit loops; they contract in an organized knitting pattern. The traditional method used to evaluate NPR is to measure the lateral fabric deformation during axial tensile testing on a mechanical testing machine, which is time-consuming and inaccurate in measuring uneven deformations. In this study, an efficient method was developed to evaluate the NPR of weft-knitted fabric that can also estimate deformation directionality. The elasticity and extension properties of the weft-knitted fabric can be analyzed immediately following removal from the knitting bed. Five fabrics, all with the same stitch densities (including four auxetic patterns and one single jersey pattern), were designed and produced to validate the proposed method. The use of our estimation method to evaluate the Poisson’s ratio of such fabrics showed higher values compared with the traditional method. In conclusion, the deformation directionality, elasticity, and extensionality were examined. It is anticipated that the proposed method could assist in the innovative development and deployment of auxetic knitted metamaterials. Full article