Knitted Fabrics Research Articles

Sustainable pre-treatment of cellulose knitwear in digital pigment printing processes

PurposeIn the field of research on the application of digital printing to textile materials, there are still many research issues that arise from the very demanding interaction of digital printing technology and the complex, heterogeneous surface system of textile materials. This is precisely why the area of pre-treatment of textile materials is in need of research, and the purpose of this research was to establish the level of influence of physical and chemical activation of the textile surface with plasma and the possibility of improving the quality of the print and colour reproduction.Design/methodology/approachThe paper deals with the possibility of applying argon and oxygen cold low-pressure plasma in the processing of cellulose knitted fabrics, with the aim of improving the quality of the print and colour reproduction in digital pigment inkjet printing. The selected raw material samples were 100% raw cotton and lyocell. After plasma treatment, the samples were printed by digital ink jet printing with water-based pigment printing ink. An analysis of the micromorphological structure of untreated and plasma-treated samples before and after printing was carried out, and a comparative analysis of the colour of the printed elements was carried out depending on the pre-treatment.FindingsThe conducted research showed a positive influence of plasma pre-treatment on the coverage of the fibre surface with pigments, the uniformity of pigment distribution along the fibre surface and the uniformity of the distribution of the polymeric binder layer. This has a positive effect on colour reproduction. Also, certain improvements in colourfastness to washing were obtained.Research limitations/implicationsConsidering the complexity of the topic, although exhaustive, this research is not sufficient in itself, but opens up new questions and gives ideas for further research that must be carried out in this area.Practical implicationsAlso, this kind of research contributes to the possibility of adopting the idea of industrial plasma transformation, as an ecologically sustainable functionalisation of textiles, which has not yet been established.Originality/valueThis research is certainly a contribution to the establishment of acceptable textile pre-treatment methods in the field of digital printing, as one of the key quality factors in digital textile printing (DTP). Considering the still large number of obstacles and unanswered questions encountered in the field of digital printing on textiles, this kind of research is a strong contribution to the understanding of the fundamental mechanisms of the complex interaction between printing ink and textile.

Bending shape memory properties and multi-scale viscoelastic behaviors of knitted-fabric reinforced polymer composites

Knitted fabrics with easily deformable loop structure have the potential in the development of shape memory polymeric composites with large recovery deformations. The knitted fabric reinforced shape memory epoxy polymer composites (SMPC) were prepared in this work. The effects of loop densities, orientations and bending radii on shape memory properties of SMPC were investigated. The shape fixity ratio and shape recovery ratio of SMPC subjected to U-shaped bending radius of 5 mm are above 98 %. The shape recovery force of SMPC can reach up to 5.9 N. The thermodynamic properties of SMP were also characterized to obtain mechanical parameters and a user-defined material subroutine (UMAT) of shape memory epoxy polymer (SMEP) was written. Based on viscoelastic theory and the multi-scale geometrical structures, the macroscopic homogeneous thermodynamic model and mesoscopic thermodynamic model of knitted fabric reinforced SMPC were established to study the macro-scale stress distribution and meso-scale deformation evolution during shape memory process, respectively. The neutral surface position of SMPC during bending deformation is offset inner. The unique anisotropic loop structure of knitted fabric determines the shape memory behavior of the SMPC. Finally, micro-CT characterizations of knitted fabric reinforced SMPC were conducted to further understand the loop deformation mechanism during shape memory process. This study will provide important theoretical and technical support for large deformation structure design and deformation prediction of smart composites.

Comparative Performance Evaluation of Ultrasonic Welding and Conventional Sewing Methods in Knitted Fabrics

Abstract When transforming two-dimensional fabric pieces into three-dimensional clothing with different sewing methods, choosing the proper technique is one of the primary factors affecting the quality of the product. Within the scope of the study, five different types of knitted fabric alternatives, which are frequently used in products for daily use, are discussed. The conventional joining methods (lock stitch and overedge stitching) and ultrasonic welding were evaluated in terms of joint performance. All the evaluations made in terms of seam strength and seam efficiency showed that the overedge stitch is more performant in sewing knitted fabrics. One of the critical advantages of ultrasonic welding, the absence of the need for needle and thread and the absence of these costs, necessitated the evaluation of one more feature of the joining methods in the study. In this context, the energy consumption values of all the methods were evaluated. As a result, the energy consumption value of ultrasonic welding is approximately 1.3 times higher than overedge stitching and approximately 10.7 times higher than lockstitching.

Thermoelectric generator modules based on warp knitted glass fiber-metal hybrid composites

Thermoelectric generators (TEG) offer the potential to convert waste heat into electricity and thus contribute to reduce CO2 emissions. The conversion of electrical energy is based on the Seebeck effect of two electrically conductive materials without any mechanical conversion and therefore without wear. The application of conventional TEG modules is limited due to cost-intensive materials and production technology of TEG, and a limited structure design for the integration of Thermoelectric Elements (TE). To address this research challenge, this work presents the development of thermoelectric composite modules based on glass fiber reinforced warp knitted spacer fabrics. In a double needle bed warp knitting machine, glass fibers in warp, weft and pile direction are integrated. The contacting of TE in the form of wires with 45 TE cm−2 were implemented. A TEG module with 20.25 cm2 in size showed a maximum output power of 2.7 μW at a temperature difference of 60 K. The Seebeck factor of S = 142 μV K−1 was determined using this composite TEG with 10 TE strands and nearly 400 thermocouples. A thermoelectric model was developed for the calculation and the modules were characterized. For the first time, thermoelectric composite modules with sufficient structural-mechanical properties in terms of compressive and bending stiffness were realized based on spacer warp knitted fabrics, which can be used for the operation of sensors or small devices.

Evaluation of Underwear Bamboo/Cotton Knitted Fabrics Comfortability

Evaluation of Underwear Bamboo/Cotton Knitted Fabrics Comfortability

Testing relationship of bending rigidity with drape coefficient for silk viscose blended knitted fabrics

Testing relationship of bending rigidity with drape coefficient for silk viscose blended knitted fabrics

NEW APPROACHES TO JUSTIFICATION OF MATERIALS FOR GARMENTS USING THE EXAMPLE OF A MEN’S T-SHIRT

The possibility of using modern methods of virtual fitting of clothes on an avatar of the human body in the process of forming the quality of garments is shown. A general scheme for calculating the me-chanical processes developed in garments when fitting the human body in statics and dynamics is presented, as well as the main directions for automating the calculation process. Based on the chosen numerical method, the problem of selecting textile materials to ensure the required quality of the product was solved using the example of a men’s T-shirt. The mechanical properties of several samples of knitted fabrics for such products were determined. Based on the obtained values, the calculation of stress fields in the parts of a men’s T-shirt in various body avatar poses was carried out. An experimental verification of the modelling results was carried out. Regularities have been established between the mechanical properties of knitted fabric and the nature of stress in the structure of the product. The possibility of their use when choosing textile materials is shown from the point of view of ensuring the required quality of products at the design stage.

Effect of layering outerwear on innerwear and air gap between the two layers on thermal comfort properties of knitted fabrics

PurposeIn everyday life, people generally wear two layers of clothes (a knitted vest and a knitted t-shirt) during the summer. It is essential to understand which types of innerwear and outerwear maximize comfort. The primary objective of this research is to investigate the influence of layering outerwear on innerwear, as well as the air gap between two layers, on thermal comfort properties.Design/methodology/approachIn this study, a total of 12 combinations were created from four vest fabrics and three T-shirt fabrics. The thermal properties (thermal conductivity, thermal resistance, thermal absorptivity, thermal diffusion and peak heat flow) were evaluated for the individual inner and outer layers. Each inner layer was layered with an outer layer to observe the effect of layering on the thermal properties. An air gap of 2 mm was introduced between the inner and outer layers to study the effect of air gap on thermal properties.FindingsTencel fibre exhibits higher thermal conductivity and absorptivity than cotton and polyester. Upon layering an outer layer on an inner layer, the thermal conductivity and thermal absorptivity increase to a slight extent, thermal resistance and diffusion increase drastically and the peak heat flow reduces. With an air gap between the two layers, the thermal conductivity did not improve, the difference in thermal resistance among all the combinations reduced, the thermal absorptivity of the combination textiles was lower than that of the innerwear alone, the thermal diffusion increased and the peak heat flow diminished for all the combinations.Practical implicationsIn practice, this comprehensive thermal comfort analysis provides specific combinations of inner and outer articles of clothing that are most appropriate for enhancing comfort during the summer season.Originality/valueThough there are many studies on the effect of multilayer fabrics on thermal properties, no extensive research analyses the influence of innerwear and outerwear combinations on thermal comfort properties.

Preparation and properties of biodegradable directional water transport composite fabrics

AbstractMoisture (i.e., sweat) management is essential for maintaining human physiological comfort. But conventional fabrics and moisture‐absorbent and quick‐drying fabrics cannot simultaneously possess directional water transport (DWT) functionality and environmental protection characteristics, while also causing a sticky sensation on the skin when worn. Herein, the polylactic acid (PLA) electrospun membranes were deposited on the PLA side of a double‐yarn weft‐knitted fabric (hydrophobic PLA filament and hydrophilic cotton yarn) with asymmetric wettability, and green composite fabrics with papillary structures and unidirectional moisture transport capability were obtained using hot‐press. The properties of these composite fabrics were evaluated by scanning electron microscopy, moisture management testing, dynamic scanning calorimetry, water contact angle (WCA), and water permeability. The results showed that the wettability gradient difference between the two sides of the fabric increased, enhancing the unidirectional moisture transport capability. The optimal performance composite fabric achieved an accumulative one‐way transport capacity of 1285% and an overall moisture management capacity of 0.693. Additionally, the WCA on the hydrophobic side measured 150°, remaining at 146.8° after two washes. Overall, this composite fabric strikes a balance between biodegradability and exceptional DWT performance, rendering it an environmentally friendly and recyclable choice for moisture‐wicking and quick‐drying apparel applications.Highlights Created PLA/cotton‐knitted fabric with asymmetric wettability. Hydrophobic PLA membrane deposited on fabric surface using electrospinning. Green composite fabrics with excellent DWT functionality were made by hot‐press. Best composite fabric: R‐value 1285.6%, OMMC 0.696, WCA 150°. Best composite fabric retains WCA of 146.8° after two washes.

Experimental investigation of pseudo-ductility in plain weft-knitted epoxy composite laminates under tension

The inherent brittleness of unidirectional fiber-reinforced composites represents a major complication in their broad practical applications. However, exploiting different reinforcement architectures can offer an opportunity for highly desirable ductile fracture nature. This article is aimed at investigating experimentally the tensile behavior of an epoxy laminate reinforced by different layers of plain weft-knitted fabrics. The fabricated laminates were subjected to uniaxial tension in different loading directions, and the corresponding tensile responses were recorded. Basic mechanical properties were characterized and digital image correlation (DIC) was employed to capture surface deformations. Tensile test results demonstrated strong nonlinearity and pseudo-ductility as well as loading-direction dependence in this type of composite laminates. Fracture tests were conducted showing high fracture toughness ranging from 10 to 20 MPa·m1/2. Typical damage modes were characterized using microscopy, which were coupled to a few distinct tensile deformation stages. This work demonstrates that weft-knitted composites are promising in permitting great amounts of pseudo-ductility with clear warning before complete failure. It is also expected to contribute to the understanding of the specific role of weft knit fabrics in composite laminates.

A Review of the Electrical Conductivity Test Methods for Conductive Fabrics

With the substantial growth of the smart textiles market, electrical properties are becoming a basic requirement for most of the advanced textiles used in the development of wearable solutions and other textile-based smart applications. Depending on the textile substrate, the test method to determine the electrical properties can be different. Unlike smart fibers and yarns, the characterization of the electrical properties of fabrics cannot be tested between two connection points because the result would not represent the behavior of the entire fabric, so the electrical properties must be related to an area. The parameters used to characterize the electrical properties of the fabrics include resistance, resistivity, and conductivity. Although all of them can be used to indicate electrical performance, there are significant differences between them and different methods available for their determination, whose suitability will depend on the function and the textile substrate. This paper revises the main parameters used to characterize the electrical properties of conductive fabrics and summarizes the most common methods used to test them. It also discusses the suitability of each method according to several intervening factors, such as the type of conductive fabric (intrinsically or extrinsically conductive), its conductivity range, other fabric parameters, or the final intended application. For intrinsically conductive woven fabrics, all the methods are suitable, but depending on the requirements of conductivity accuracy, the contact resistance from the measuring system should be determined. For intrinsically conductive knitted fabrics, two-point probe, Van der Pauw, and eddy current methods are the most suitable. And for intrinsically conductive nonwoven fabrics, two-point probe and four-point probe methods are the most appropriate. In the case of extrinsically conductive fabrics, the applied method should depend on the substrate and the properties of the conductive layer.

Modern Electromagnetic-Radiation-Shielding Materials Made Using Different Knitting Techniques.

This paper summarizes the possibility of employing knitted textile barriers as a shield against electromagnetic fields to protect the human body from their negative impact. Ten variants of knitted fabrics made of electrically conductive yarns, steel, and copper wire that differed in stitch pattern, structural parameters, and raw material, were designed, manufactured, and tested. The knitted fabrics produced differed in structural parameters, including course and wale density, surface density, thickness, thread length in the loop, wale and course take-up, volume cover factor, and surface porosity. These parameters were examined in accordance with the research methodology used in knitting. Barrier measurements were taken in the direction of the wales and in the direction of the courses for two frequencies of electromagnetic fields: 2-4 GHz and 4-7 GHz. It was observed that the shielding effectiveness of the manufactured materials depends on the structural parameters of the fabric, the stiches applied, and the type of yarn.

Comparing Sensorial Comfort Properties of Cotton, Cotton/Linen and Linen Knitted Fabrics

ABSTRACT Linen fibers exhibit good moisture management properties and can effectively conduct heat. However, there are limited studies on the sensorial comfort properties of linen knitted fabrics. In this study, the sensorial comfort properties of optical bleached, different enzyme washed and softened 100% cotton, 50% cotton/50% linen, and 100% linen fabrics were investigated using the Kawabata KES-FB evaluation system. The results showed that the tensile resilience and compression linearity values of the 100% linen fabrics were higher than those of other fabrics. The compression energy and compressional resilience of the 50% cotton- 50% linen fabrics were higher than those of the other fabrics. The surface friction value of 100% linen fabrics can be improved by cellulase enzyme treatment. Pectinase enzyme treated fabrics showed higher smoothness values than cellulase enzyme treated 100% linen fabrics.

Light transmission in knitted fabrics through polymeric optical fiber insertion for advanced textile applications

Smart textiles are prominent in the textile industry, with applications in various technical areas such as medicine, architecture, sports, and esthetic purposes, among others. Within this concept, optical fibers are classified as passive smart textiles and are highly attractive for clothing lighting and monitoring physiological parameters. This study aimed to present methods for inserting polymeric optical fibers into weft single knitted fabrics and verifying the loss of luminosity in them, analyzing the technical feasibility of developing e-textiles to be applied in monitoring. For such, weft knitted fabrics were produced by altering the optical fiber insertion methodology, defined as inlay insertion and insertion in the course direction, each subdivided into different methods. Light transmission was verified using a laser pen connected to the optical fiber. Images were captured and analyzed using LILP software to verify and quantify the loss of luminosity in each insertion method. Light transmission microscopy was performed to evaluate the surface of the polymeric optical fiber used. For the insertion techniques performed, inlay and by course direction, the result obtained for signal transmission was satisfactory; however, the inlay insertion methods presented lower light emission but lower luminosity loss than the insertion by course direction. This result is very interesting because it enables the development of weft knitted fabrics from the use of optical fibers for application in various types of monitoring.

Analysing the effect of mechanically recycled cotton fibres from pre-consumer wastes on mechanical and fastness properties of knitted fabrics

Analysing the effect of mechanically recycled cotton fibres from pre-consumer wastes on mechanical and fastness properties of knitted fabrics

Towards optimization of sports bra strap design: the role of stitch pattern and stitch length (SL) on the properties of seamless knitted fabrics

The purpose of this study was to investigate the effect of SL and stitch patterns on seamless knitted fabric properties as applied to sports bra strap functionality. Different tuck stitch patterns commonly used for seamless knitted activewear, were knitted with a Santoni machine setting for stitch SL = 70. Textile testing was conducted to narrow down the patterns suitable for bra strap. Significant interactions between pattern and SL on thickness, weight, air permeability, elongation, and breaking force were found. The results confirmed some of the existing knowledge about the influence of tuck stitches on the dimensional properties of weft knitted fabrics, such as increasing their density and stability, but also revealed new insights for patterns with more complex tuck stitch repeats when varying SL. Moisture management measurements for various SL values proved to be critical in selecting the best stitch pattern (tuck pattern#10) and SL = 115 that could lead towards optimization of sports bra strap design and highlighted the inconsistent tuck pattern fabric behavior in the presence of moisture.

Three-dimensional modeling of the mechanical tensile behavior of metal weft-knitted fabric made from NiTi wire

In this work, the reasons for the difference between the deformation curves of TiNi wire and the metal knitted fabric made of it under uniaxial tension in the load-unload cycle have been investigated. Experimental stress-strain diagrams of NiTi wire under uniaxial tension to rupture and in the load-unload cycle have been obtained. The phase composition of the wire at each loading stage was investigated. The load curves of the NiTi wire under uniaxial tension has three linear sections corresponding to the following evolution of phase composition: up to 2% there is a section of elastic deformation of 91% austenite; in the strain range from 2% to 11% there is a plateau section associated with direct phase transformation from austenite to monoclinic martensite; the strain range from 11% to 18% is a linear hardening section associated with deformation of 69% monoclinic martensite. An accurate geometric model was developed and the stress-strain state of the metal weft-knitted fabric was evaluated to understand the mechanism of the transition from superelastic to hyperelastic deformation behavior. Direct phase transformation in metal weft-knitted web starts at a relative strain of 8% at a stress of 278 MPa. The stress reaches the ultimate strength of the wire of 684 MPa at a strain of 16.3%, and increasing the strain up to 20% causes the formation of new defect areas, mainly where the loops are in contact with each other. The calculated cyclic curve of the periodic unit cell of the metal weft knitted fabric is typical of hyperelastic materials and differs from the deformation curve of the titanium nickelide wire.

COMPARISON OF ANTIBACTERIAL AND SOME PHYSICAL PROPERTIES OF KNITTED FABRICS PRODUCED FROM BAMBOO, COTTON AND VISCOSE FIBER

Cotton, bamboo, and viscose fibers were examined in this study for their suitability in textile production. Bamboo, being a regenerated cellulosic fiber, has gained popularity in the industry due to its ecological properties. Fabrics made from bamboo exhibit comfort, wrinkle resistance, and thermal regulation. Additionally, they possess natural antibacterial, hypoallergenic, and biodegradable properties, along with high moisture absorption, shine, softness, and UV protection. The study compared knitted fabrics from these fibers, evaluating their water vapor permeability, air permeability, burst strength, water absorbency, abrasion resistance, and antibacterial properties according to international standards. Results showed that bamboo and cotton fibers have similar water vapor permeability, both higher than viscose fibers. Bamboo fiber's air permeability is notably higher than cotton and viscose fibers. Moreover, bamboo's water absorption surpasses cotton and viscose, leading to better sweat absorption. Bamboo fiber also demonstrated superior antibacterial properties compared to cotton and viscose, with higher bacterial eradication rates. Fabrics made from bamboo exhibited higher bursting strength and comparable pilling values to cotton, outperforming viscose. Overall, bamboo fiber demonstrated better air permeability, water absorbency, antibacterial properties, abrasion resistance, and bursting strength compared to cotton and viscose, making it a desirable choice for cool and comfortable textiles.

A Highly Durable and UV‐Resistant Graphene‐Based Knitted Textile Sensing Sleeve for Human Joint Angle Monitoring and Gesture Differentiation

Flexible strain sensors based on textiles have attracted extensive attention owing to their light weight, flexibility, and comfort when wearing. However, challenges in integrating textile strain sensors into wearable sensing devices include the need for outstanding sensing performance, long‐term monitoring stability, and fast, convenient integration processes to achieve comprehensive monitoring. The scalable fabrication technique presented here addresses these challenges by incorporating customizable graphene‐based sensing networks into knitted structures, thus creating sensing sleeves for precise motion detection and differentiation. The performance and real‐world application potential of the sensing sleeve are evaluated by its precision in angle estimation and complex joint motion recognition during intra‐ and intersubject studies. For intra‐subject analysis, the sensing sleeve only exhibits a 2.34° angle error in five different knee activities among 20 participants, and the sensing sleeves show up to 94.1% and 96.1% accuracy in the gesture classification of knee and elbow, respectively. For inter‐subject analysis, the sensing sleeve demonstrates a 4.21° angle error, and it shows up to 79.9% and 85.5% accuracy in the gesture classification of knee and elbow, respectively. An activity‐guided user interface compatible with the sensing sleeves for human motion monitoring in home healthcare applications is presented to illustrate the potential applications.

Towards seamless conformable and comfortable wearable electronics: Polyimide-supported dry electrodes integrated in knitted fabrics

Wearable electronics contribute directly to advancing numerous biomedical devices in contract with the human body. These electronic devices have been transformed from rigid and bulky into soft and flexible. Conformable electronics is actively pursued in the literature to comply with the curvilinear surface of the skin. To increase the adoption rate, seamless comfortable operation is necessary, which requires more focus on convenient materials such as textiles, compared to elastomer-based technologies. This study demonstrates mechanically reliable stretchable interconnects embedded within textile to achieve both conformability and comfort. Electromyography (EMG) signals provide invaluable information about body motion analysis, muscle nerve and fatigue disorders. Non-invasive surface EMG is the preferred method of measurement since it can be conducted with minimal risk to the subject. In this study, polyimide-supported dry electrodes are integrated in knitted fabrics using a special knit pattern to ensure achieving higher contact surface area with the human skin. The received EMG signals are benchmarked against standard wet electrodes in time and frequency domain, revealing comparable performance. The presented technology exhibits extremely high mechanical reliability, withstanding up to 10,000 cyclic elongations at 60 % strain. The integration strategy is sufficiently strong and durable, retaining its electrical properties after 20 standard washing cycles. The findings indicate that the presented technology holds significant promise towards real-world implementation of seamless, conformable, and comfortable wearable electronics.