Mechanical Properties Of Yarns Research Articles

Prediction of tensile behavior of compression therapeutic biomedical materials by mesoscale laid-in loop model

Tubular laid-in weft-knitted compression (LWC) therapeutic materials have been extensively applied in medical clinic treatment and daily healthcare management. Limited studies have explored the mechanical mechanisms through the numerical analytical models for the development and performance prediction of laid-in fabrics. This study developed the three-dimensional (3D) finite element (FE) laid-in loop model to simulate and predict the tensile behaviors of LWC materials based on the determination of geometric models and investigation of yarn mechanical properties. Through the constructed FE mesoscale models with various physical-mechanical characteristics of inlay yarn materials, it was found that the ground yarns and inlay yarns played distinct roles in producing tensile stresses under the course and wale direction of stretching strains. These tensile stresses determined the selection of yarn materials for controlling the tension of laid-in knitted fabrics in end applications. Then, the interfacial pressure dosages exerted by LWC materials were quantitively obtained based on the simulated Young's moduli values and modification of Laplace's Law model. The accuracy and acceptability of proposed mechanical laid-in models (mean error: 10.22 %) and pressure prediction models (mean error: 14.70 %) were validated by the comparative studies. The simulation methods and results created a visual tool for dynamically illustrating the tensile behaviors and predicting pressure performances of the elastic therapeutic materials in functional material design of biomedical compression textiles.

An efficient virtual modeling regard to the axial tensile and transverse compressive behaviors of the twisted yarns

The mechanical properties of yarns have a decisive effect on the performance of fiber-reinforced composite materials. Predictive simulations of the mechanical response of yarns are, thus, necessary for damage evaluation and geometric reconstruction of textiles. This paper proposed a quasi-fiber scale virtual modeling method regard to the axial tensile and transverse compressive behaviors of the twisted yarns. A stochastic properties model of the yarn was established for characterizing the statistical distribution of tensile strength. The variation of modeling parameters, including coefficient of friction, the amounts of virtual fibers per yarn and element length, versus calculation accuracy has been determined based on axial tensile and transverse compressive behavior of quartz fibers. The relationship between modeling parameters and mechanical behavior of yarn was established within the scope of this study. Axial tensile and transverse compressive behavior of yarns with different twists were predicted. The results show that balance between the modeling precision and computational efficiency can be achieved using the parameters, the COF of 0.35, virtual fiber count of 122 and Le of 0.3. This efficient modeling method is meaningful to be developed in further virtual weaving research.

Numerical investigation on hybridization of woven fabric armour to enhance ballistic protection

The soft ballistic armour design requirement involves maximum ballistic energy absorption with lower backface deformation at minimum possible weight. Yarn mechanical properties play a primary role in influencing the above armour characteristics. The study reported to date has analysed the yarn properties, which will yield maximum ballistic energy absorption. However, finding the optimal combination of yarn mechanical properties that will simultaneously satisfy all the above objectives is still a matter of investigation. In view of this, the study first introduces a new parameter, “Inertial Work” (product of armour mass and backface deformation) which enables categorization of armour backface deformation in a mass normalized manner. Further, Specific Ballistic Energy Absorption (SBEA) parameter is introduced for comparison across the fabrics of different densities. The woven fabrics widely used in the ballistic protection domain Kevlar 29, Zylon AS and Spectra 1000 were extensively analysed numerically to study their ballistic response. FE simulation results showed that a single material armour would prove insufficient to simultaneously attain the above design characteristics. Hence a concept of hybridized multilayer-multimaterial armour was established to address this lacuna. It was found that hybridization significantly influenced the ballistic performance of armour. The arrangement of maximum layers of high toughness, low modulus – high failure strain material (Kevlar 29) in front, followed by a material with similar toughness but higher strength (Zylon AS) and then minimum layers of low toughness and low failure strain material (Spectra 1000) at the back resulted in higher SBEA and lower Inertial work.

Prediction of Mechanical, Evenness and Imperfection Properties of 100% Cotton Ring Spun Yarns with Different Twist Levels

The purpose of this research work is to develop a model to predict the effect of twist on mechanical, evenness and imperfection properties of 100% cotton ring spun yarns. Eight yarns were manufactured from 30Tex with four yarn twist increments (700, 740, 780 and 820TPM), and 15Tex with twist levels of 900, 1020, 1080 and 1140TPM (turns/meter). Except yarn count and twist level, the yarns were made from the same fiber properties and machine settings. Yarn mechanical properties such as tensile strength, elongation and abrasion resistance, evenness (CVm) and imperfection characteristics like hairiness, neps, thin and thick places were measured and statistically analyzed. Equations were developed to predict the desired mechanical, evenness, and imperfection properties of yarns based on yarn count and twist levels. Statistical analysis showed that yarn properties are significantly influenced by count and twist level changes. The tensile strength, elongation, abrasion resistance, CVm, hairiness and thick places of the studied yarns were significant at P-values of 0.000, 0.003, 0.000, 0.004, 0.000 and 0.015 respectively. Generally, as yarn twist increases, breaking strength and abrasion resistance increase, whereas elongation, hairiness, coefficient of mass variation (CVm), thin and thick places, and nep of yarn decrease. Therefore, the formulated multiple regression equations would be useful in predicting yarn properties based on its count and twist.

Study on the performance characterization and yarn mechanical properties of poly-m-phenylene isophthalamide nanofiber

In this paper, poly- m-phenylene isophthalamide (PMIA) staple fibers were dissolved in a LiCl/ N, N-dimethylacetamide solvent system in order to prepare PMIA nanofibers via the electrospinning method. The mean diameter of the nanofiber was between 72 and 247 nm and gradually increased with increasing LiCl concentration. PMIA nanofibers were characterized by scanning electron microscopy, Fourier transform infrared spectrometry, a thermogravimetric analyzer and Brunauer–Emmett–Teller analysis. Besides, the tensile strength of PMIA nanofiber yarns was tested and analyzed, combining the orthogonal array method. The results showed that the diameter and uniformity of nanofibers decreased gradually with increasing PMIA and LiCl solution concentration. The thermal properties, the specific surface area and chemical structures of PMIA nanofibers were improved comparing with PMIA stable fiber. It was found out that the LiCl concentration could influence the interactions among polymer molecules and caused the fibrils to wrap around each other, forming fiber clusters. The LiCl concentration was the most important factor affecting the tensile strength of PMIA nanofiber yarn.

Role of Fabric Structure on the Second Tensile Elastic Modulus of Net Warp-Knitted Fabrics

This work aimed to study the second elastic modulus of net warp-knitted fabrics (NWKF) experimentally and theoretically. Net knitted fabrics were selected to study owing to their wide practical application and also lack of enough attention. Knitted fabrics have two regions of tensile elastic behavior which the initial one refers to the displacement of the elements of fabrics before jamming of the yarns. As soon as jamming takes place completely, the constituent yarns in the structure of fabrics go through tension. In other words, yarns in their spatial configuration resist the applied loads. This resistance is important in the ultimate strength of the fabrics and also in the composite materials reinforced with knitted fabrics. NWKFs were produced using a Raschel knitting machine. Uniaxial tensile tests were conducted in the course and wale directions. The second elastic modulus was measured using a statistical approach. In the theoretical part, a mechanical model based on the configuration of elements of fabrics after jamming status and using Energy method and Castigliano’s Theorem was proposed. The proposed model was used to calculate the second elastic modulus. To validate the model, the authors’ experimental data along with the collected data from the other researches were compared with the calculated values, and the results showed that the proposed model can predict the modulus reasonably. The results showed that the fabric structure including wale spacing, course spacing, and the number of lapping movements creating the holes affects the second elastic modulus despite the accepted concept, but the mechanical properties of yarns only influence the second elastic modulus of the fabrics.

Characterization of Natural Reinforcements and their Composites

In this study, the mechanical properties of flax, jute and jute/carbon woven fabrics, and their composites were investigated and compared with 3K carbon fabric composites. Mechanical properties of yarn, fabric and composites were separately investigated and compared for each scales. In addition, yarn and fabric structures were characterized. It was found that, fabric structure, yarn physical properties and fiber cross-section and fiber molecular structure parameters of reinforcement have seriously effect on the composite mechanical properties. It can be concluded that fabric tensile strength attribute to composite tensile strength, but there was not a direct relation between fabric tensile strength and composite tensile strength. The tensile strength of natural fiber fabrics were determined to be significantly reduced depending on the temperature increasing. This condition should be considered as a important limitation for composite applications of natural fibers. Mechanical test results are proved that natural fiber composites not to be an important alternative to conventional composites.

Study on the Properties of Cotton Yarn with Modified Yarn Path in Ring Spinning

Spinning triangle is a critical area that influences the physical and mechanical properties of yarn. Previous researchers have done several works related to spinning triangle by modifying yarn path primarily considering only one side diagonal yarn path meaning that either left or right diagonal yarn path. The others used single yarn count and twist level on different variety of raw materials. This research was produced cotton ring yarns by varying count (36 Ne, 40 Ne) and twist level (1014 TPM, 1080 TPM) using right and left diagonal paths in Z-twist direction. The yarns were tested and it was observed that 25%, 0.34%, 37% and 25% reduction in hairiness, CVm%, thin place and thick place respectively with slight decreasing of tenacity in left diagonal path yarn. In right diagonal path yarn there is 3%, 16%, 59% and 14% increasing of yarn hairiness, CVm%, thin place and thick place respectively with 10% reduction of tenacity. Therefore, the left diagonal path has a significant improvement of ring spun yarn quality in terms of physical properties. On the other hand, the right diagonal path yarn were deteriorated all the physical and tensile properties of ring spun yarn. This is occurring due to the mismatching of right diagonal path with Z-twist direction.

Influential Parameters of Starching Process on Mechanical Properties of Yarns Intended for Multifunctional Woven Fabrics for Thermal Protective Clothing.

The investigation of influential parameters of the starching process on mechanical properties of yarns intended for multifunctional woven fabrics for thermal protective clothing was performed on four different yarn samples starched on an innovative starching machine, adapted to industrial starching conditions. The starching was conducted with two different processes with different starch mass concentrations: the standard starching process and a newer starching process (with yarn prewetting). Based on the results obtained, it can be concluded that starching positively affects all the properties of tested samples and that the increase of starch mass concentration is not accompanied by the improvement of those yarn properties. Synthetic polymer fibers that achieve satisfactory yarn strength need to be starched with lower starch mass concentrations in order to retain the breaking properties and to be protected from abrasion and static electricity, which occurs during the weaving process. The yarn prewetting starching process shows significantly better results than the standard starching process, especially for aramid yarns, where abrasion resistance increased from 42 to 135%. Therefore, we can conclude that the goal of starching such yarns is aimed at increasing the wear resistance. Linear regressions and correlations between the values of breaking properties and abrasion resistance obtained by the testing and their values that were estimated by the analysis show a high correlation coefficient.

Highly Stretchable and Flexible Melt Spun Thermoplastic Conductive Yarns for Smart Textiles.

This study demonstrates a scalable fabrication process for producing biodegradable, highly stretchable and wearable melt spun thermoplastic polypropylene (PP), poly(lactic) acid (PLA), and composite (PP:PLA = 50:50) conductive yarns through a dip coating process. Polydopamine (PDA) treated and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated conductive PP, PLA, and PP/PLA yarns generated electric conductivity of 0.75 S/cm, 0.36 S/cm and 0.67 S/cm respectively. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the interactions among the functional groups of PP, PLA, PP/PLA, PDA, and PEDOT:PSS. The surface morphology of thermoplastic yarns was characterized by optical microscope and Scanning Electron Microscope (SEM). The mechanical properties of yarns were also assessed, which include tensile strength (TS), Young’s modulus and elongation at break (%). These highly stretchable and flexible conductive PP, PLA, and PP/PLA yarns showed elasticity of 667%, 121% and 315% respectively. The thermal behavior of yarns was evaluated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Wash stability of conductive yarns was also measured. Furthermore, ageing effect was determined to predict the shelf life of the conductive yarns. We believe that these highly stretchable and flexible PEDOT:PSS coated conductive PP, PLA, and PP/PLA composite yarns fabricated by this process can be integrated into textiles for strain sensing to monitor the tiny movement of human motion.

Inverse approach for flax yarns mechanical properties identification from statistical mechanical characterization of the fabric

Plant fiber properties, such as morphological and mechanical, are characterized by a large dispersion. Thereby, a statistical analysis is needed to obtain consistent results. An experimental study, conducted on 50 flax yarns, shows that the flax yarn properties (Young's modulus, tensile strength and diameter) follow Gaussian distributions. This approach is obviously reliable, however time-consuming, to get relevant information. An alternative could be the identification of the yarn mechanical properties using an inverse approach, based on tensile tests conducted on flax fabric reinforcement. The aim of this study is to develop a numerical method that allows to identify the statistical distributions of flax yarn properties based on tensile tests conducted on fabric specimens. The proposed strategy relies on two assumptions. On the one hand, fabric is constituted of several yarns acting like springs in parallel. On the other hand, yarns are considered as brittle-elastic materials. Hence, a yarn breaks when the load reaches its failure strength, leading to a loading redistribution to the intact yarns. A comparison of the numerical and experimental results of flax fabric tensile behavior, and of the flax property statistical distributions allows to confirm the performance of this strategy. The results show that the flax fabric tensile behavior is correctly described by the proposed modeling strategy. The average and the standard deviation of the Young's modulus, the tensile strength and the diameter of flax yarns identified from fabric tensile tests via inverse approach are close to those obtained experimentally on individual yarns. Indeed, the measured average diameter of unitary yarns are 244.4±19.2μm and the fitted one is 2474.8±17.4μm, the fitting failure strength 292.3±33.4MPa are close to the experimental 271.2±47.5MPa. The identified Young's modulus is 9.4±0.9GPa is lower than the experimental 10.8±1.3GPa.

Micromechanical model for rapid prediction of plain weave fabric composite strengths under biaxial tension

The biaxial properties of plain weave fabric composites are important as they are more representative of the performance under complex loading conditions. Experimental determination of these properties is difficult and Finite Element Analysis provides accurate prediction but is computationally expensive and requires skilled users. To provide a simple and rapid prediction of the strength of plain weave fabric composites under biaxial tension a novel micromechanical model is proposed in this paper. To predict the biaxial tensile strengths the minimum total complementary potential energy principle is used on a micromechanical unit cell where the orthogonally interlaced yarns are idealised as curved beams. The new model is verified with a finite element method model on three warp/weft biaxial loading ratios: 1:1, 2:1 (1:2) and 3:1 (1:3) and uniaxial experimental data. The model is verified on four types of material, ranging in mechanical properties from carbon to glass fibres, and 11 yarn specifications, including five cases compared to experimental results and six cases compared to the FE model, giving a mean error of 9.85% and a maximum error of 16.74% compared to experimental results and a mean error of 10.71% and a maximum error of 14.67% compared to the FE model, which demonstrates the effectiveness of the model. The standard deviation of prediction errors among the 11 cases is 2.66%, which demonstrates the robustness of the model for a range of applications. The proposed model is able to predict the uniaxial and biaxial tensile strengths without experimental investigations at the fabric and laminate level and only requires the yarn mechanical properties and specifications.

Experimental and numerical study of inter-yarn friction affecting mechanism on ballistic performance of Twaron® fabric

Most previous numerical investigations show that inter-yarn friction is one of the critical parameters to ballistic performance of woven fabrics under ballistic impact. However, the effects of inter-yarn friction on the ballistic performance of those fabrics are not approved by empirical work. There are two premises to empirically prove the numerical analyses, where the fabric structure and yarn mechanical properties and the weight are almost kept. Our previous investigation show that TiO2/ZnO composites on the yarn surface by sol-gel treatment can keep yarn mechanical properties and weight unaffected but significantly increase the inter-yarn friction. In this way, TiO2/ZnO composites generated by sol-gel treatment were coated to the ballistic fabrics through dip-pad-dry process to vary the inter-yarn friction. Ballistic perforation tests were conducted to those fabrics under impact velocity of 460-500 m/s with one-gram weight cylindrical projectile and the numerical simulation work were also carried out. Through comparisons between ballistic impact tests and numerical results, it shows that higher inter-yarn friction is better for energy absorption, especially at more fabric layers. Both numerical analysis and experimental work have approved that higher inter-yarn friction would lead to more large areas engaged in energy absorption and shear broken become more pronounced.

PEG‐PLA‐PCL based electrospun yarns with curcumin control release property as suture

AbstractThis work presents an interesting method using an electrospinning process to fabricate suture yarns loaded with curcumin to achieve reasonable mechanical properties as well as tunable drug release behavior. Different structures including different yarn counts and twists as well as core‐sheath structures were used to adjust drug release properties along with improving the yarn's mechanical properties. The core parts were made of polycaprolactone and the sheath parts were made of polyethylene glycol, polylactic acid, and polycaprolactone. Drugs can be incorporated in both parts based on the required condition and application. Electrospun yarns were compared using both structural properties and their drug release profiles as metrics. The results of comparing drug release profiles of six electrospun yarns with different yarn counts and twists showed that yarns with finer fiber diameters in the core part have more drug release as well as more initial release. Overall evaluations showed that core‐sheath drugloaded yarn with appropriate physical and mechanical properties can be a useful material as a drug delivery system to the site of damaged tissue. It can also be concluded that the amount and duration of drug release can be controlled using the structural parameters of electrospun yarns as an engineering tool for designing suture yarns with required properties.

Effect of spinning factors on stress-strain curves in egyptian cotton

This investigation aimed to determine the effect of spinning system, yarn count and twist multiplier and their interactions on single yarn mechanical properties. Also, the Stress-Strain curves were plotted with the yield points and breaking points and their corresponding yarn properties (toughness, stiffness and Initial Young Modulus) were derived and calculated. As well as, the relative importance % of three spinning factors toward the single yarn mechanical properties was measured.Resultsrevealed that the main effects of spinning factors i.e. spinning system, yarn count and twist multiplier were generally significant or highly significant on all single yarn mechanical properties except stiffness and initial Young's modulus. Regarded the first and second order interaction effects, they were no significant for all single yarn mechanical properties indicating that each one of the three spinning factors reflected similar behavior under the other two factors. It is obtained that the compact and ring spinning systems produced yarns are markedly stronger, good elasticity and more durable than the yarns spun by open-end system. Result indicates that finer yarns are weaker and have lower extension at break than coarser yarns. It is obvious that yield strain, breaking extension, breaking tenacity and toughness significantly increased as a result of increasing the twist multiplier from 3.5 up to 4.5. Results exhibited that the spinning factors explained the most single yarn mechanical properties variation expressed as coefficient of determination (R2). The maximum relative importance % was obtained by yarn count followed by twist multiplier for yield strain, yield stress and breaking extension while the spinning system was the second important factor for breaking tenacity and toughness. On the other hand, it is appeared that the studied spinning variables accounted for least and ineffective part of the variation of stiffness and Initial Young's Modulus.

Effect of some Egyptian Cotton Varieties and Grades on Fibers and Yarn Mechanical Properties

This investigation was carried out at Plant Production Department, Faculty of Agriculture (Saba-Basha), Alexandria University, Egypt and at Cotton Research Institute, ARC, Giza, Egypt, to study the effect of cotton variety and lint grade on fiber and yarn mechanical properties during 2018 season. Two commercial Egyptian cotton varieties, G. barbadense namely: Giza 87 and Giza 96 as Extra-long staple (ELS) were used. Three lint cotton grades i.e., Good to Fully Good (G/FG), Good (G) and Fully Good Fair to Good (FGF/G) were used for each variety. Fibers were processed to combed yarns Ne 80. The H.V.I. classing 1000, Pressely, Stelometer and Cotton Classifying System (CCS) instruments were used to determine the physical and mechanical fiber properties.The grading system in Egypt depends upon the experience of the classer to determine grade and quality of the raw cotton according to the official grade standard of each cotton variety. The results indicated that classer's was highly significant correlated with all instrumentally measured traits (positively or negatively). The Extra-long cotton varieties had a highly significant effect for fiber properties The highest mean value of micronaire reading (3.51), maturity index (87%) , fiber length (UHML) (35.80 mm) , fiber strength (44.1 g/tex), fiber elongation(5.4 %), spinning constant index (222), reflectance degree (75.7) and trash count (112) were recorded for the Egyptian cotton variety Giza 96 .As for the lint cotton grades effect , it could be concluded that the highest lint cotton grade Good to Fully Good (G/FG) recorded the best of all fiber properties which as high value of micronaire reading , maturity index , fiber length(UHML), uniformity index, fiber strength, spinning constant index and less of short fiber index , yellowness degree and trash count vice versa. Cotton varieties (V) had highly significant differed for mechanical cotton properties measured by three instruments( HVI , Stelometer and Pressley) i.e. fiber strength and fiber elongation the highest mean values of the fiber strength ( 44.4 g / tex) , was attained by the cotton variety Giza 96. Whereas the lowest mean values (43.2 g/tex) and (4.8 %) of the fiber elongation. The conventional methods are biased toward the long, strong fibers in cotton, whereas the high speed instruments use less accurate, indirect methods to measure bundle mass and produce a force measurement that is confounded by differences in fiber crimp. When we compared single instrument testing (Pressley and Stelometer) with the HVI technology for evaluation of fiber properties is faster and coast less per measurement. The disadvantage of HVI for genetic modification for fiber properties may be reduced accuracy and ability to separate small differences. The HVI instrument had a highly significant effect on all studied fiber properties i.e. the micronaire reading , maturity index , fiber length , uniformity index , fiber strength , short fiber index, reflectance degree and yellowness degree .The highest mean value were (3.18), (85%) , (35.7mm), (86.4 %) , (47.6g/tex) , (5.7 %) , (76.0) and (9.4),respectively. of the maturity index, while the CCS instrument possessed the lowest mean of these traits. HVI measurements were calibrated across instruments using USDA cotton calibration standards making it possible to compare results from different instruments over a long period of time. In addition, cotton testing laboratories use cottons of known values throughout the day to check for a possible drift in measurements over time.

Effect of low-quality and inexpensive cotton materials on yarn properties using rotor spinning system

The current search aimed to produce medium and coarse yarns using low-quality and inexpensive cotton materials under the rotor spinning at four yarn counts being 10.s, 16.s, 20.s and 24.s with 4.4 twist multiplier. The used cotton materials were the waste from spinning extra long-staple cotton such as combed wastes, Giza 80 lint grade fully good fair, Giza 90 lint grade fully good fair, Giza 80 lint grade good fair, Giza 90 lint grade good fair, imported china variety and carded wastes. The used cotton materials were prepared from the commercial cotton samples of season 2017. The studied yarn mechanical properties were yarn strength, yarn evenness C.V.%, number of neps, number of thin places and number of thick places. However, the average values of five fiber properties being fiber length 2.5 %, short fiber content %, coefficient of variation fiber C.V. %, fiber strength and micronaire reading were measured for all used cotton materials. Results showed significant differences among cotton materials and among yarn counts for all studied yarn properties. The effect of interaction between cotton materials and yarn counts was only significant for yarn strength and yarn evenness C.V. %.Generally, it is obvious that the mean values of yarn strength were in descending order considering cotton materials of combed wastes, Giza 95 lint grade fully good fair, Giza 90 lint grade fully good fair, Giza 95 lint grade good fair, Giza 90 lint grade good fair, china variety and carded wastes, respectively. On the contrary, the mean values of yarn evenness C.V. %, number of neps, number of thin places and number of thin places were in ascending order for the same aforementioned cotton materials. The mean values of yarn strength were gradually decreased when the yarn count was increased while the mean values of yarn evenness C.V. %, number of neps, number of thin places and number of thin places were gradually increased when the yarn count was increased.

Modification of Cotton Yarns for Smart Socks Production

The functionality of textiles can be complimented by using a wide variety of modification technologies. This study focuses on textile modification with sol-gel technology as a part of smart sock prototype development. Zinc acetate dehydrate (ZAD) is integrated in sol synthesis and used as modifier thus improving modified cotton yarn mechanical properties and also can prolong time between washing, taking into account modifiers antimicrobial properties. Four hanks of pure cotton yarns with length of 300 m, where modified with silica-based sol with 7,5 wt% ZAD as a modifier. As a part of this study tensile strength and elongation of yarn was determined and changes in liner density were observed. Average yarn linear density increases by 19 % and linear density for knitted samples increases by 2,6 %. Therefore, yarn strength for 80 % of modified samples shows mean value of 2,32 N, that is 17 % higher than unmodified samples.

Evaluation of Kenaf Yarn Properties as Affected by Different Linear Densities for Woven Fabric Laminated Composite Production

Currently, there is a growing interest of using woven material in composite production for many applications such as structural applications, non-structural applications, household utilities, parts for automobile, aerospace components, flooring and ballistic laminate composites. The structure and properties of the woven fabric is very important as it dictate the woven composite properties. The properties of yarn like linear density, twist factor and strength can influence most of the woven fabric properties. Strength of woven fabric is one of the most important properties which make it superior in final composite applications. In this study, the effects of linear density i.e. 500, 1000, 1500 and 2000 tex on physical and mechanical properties of kenaf yarn were evaluated. The assessment on twist type, twist angle, yarn diameter, yarn structure, fibre density, moisture content, water absorption and mechanical properties were carried out on kenaf yarns. The yarn mechanical properties were tested on the tensile strength, Young’s Modulus and elongation. It was found that, different linear density of yarn exhibited different behavior of yarn properties. Higher linear density yarn produced wider yarn diameter compared to lower linear density yarn, resulting to higher fibre and moisture content yarn. Yarn tensile strength has increased by 46% when linear density was changed from 500 to 2000 tex due to higher amount of individual fibres. However, for Young’s Modulus, the values reduced as the yarn linear density increased due to several factors including number of fibres and moisture content of yarn.

Hand and Wear Comfort of Knitted Fabrics Made of Hemp/Tencel Yarns Applicable to Garment

This study examined the hand and wear comfort properties of hemp/tencel blend yarns and their knitted fabrics spun by ring, siro spun, and air vortex spinning machines. The tactile wear comfort properties of the air vortex yarn knitted fabric were influenced by the yarn mechanical properties resulting from the air vortex yarn structure. The high compressibility of the air vortex yarn knitted fabric made it soft and compressible to lateral deformation. The high extensibility and low bending rigidity of the air vortex yarn knitted fabric gave it a softer tactile hand property than those of the ring and siro-spun yarns knitted fabrics. On the other hand, high shear rigidity of the knitted fabric enabled the air vortex yarns to have better formability. This shows that the air vortex yarn knitted fabric has a suppler hand than those of the ring and siro-spun yarns knitted fabrics, which would justify the application possibility of hemp fibers in the air vortex spinning system.