Improvement in the fracture toughness (Mode I) of laminated glass fabric composites through air-jet texturing

Delamination is the most common failure mode in laminated composites due to the reduced strength in the through-the-thickness direction. Air-jet texturing was used to provide more surface contact between the fibres and the resin by producing bulk and loops in the yarn. The development and characterization of core-and-effect textured glass yarns and the effect of texturing on the mechanical properties of laminated composites were presented in the previous papers. This paper describes the effect of texturing on the inter-laminar fracture toughness (Mode I) of glass laminated composites. The composites of twill weave fabrics were developed from both the textured and non-textured yarn and fracture toughness is tested in warp and weft directions. Significant improvement was observed in the Mode I fracture toughness of the composites after texturing. The bulkier, loopy structure of the textured yarn provided more surface contact between the fibre and the resin and significantly improved the bonding strength.     

Mechanical properties of composites made from locally manufactured carbon fabrics and the composites produced from air-textured glass yarns

Composite materials have a wide range of applications in structural components because of their high strength-to-weight and stiffness-to-weight ratios. However, the most crucial and common life-restricting crack growth mode in laminated composites i.e. delamination is of great concern. Air jet texturing was selected to provide a small amount of bulk to the glass yarn. The purpose was to provide more surface contact between the fibres and resin and also to increase the adhesion between the neighbouring layers. These were expected to enhance the resistance to delamination in the woven glass composites. The development and characterisation of core-and-effect textured glass yarns was presented in the previous paper. This paper describes the comparison of the mechanical properties of composites produced from air-textured glass yarns and the composites made from locally manufactured carbon fabrics. The tensile, flexure and inter-laminar shear strength (ILSS) were compared and it was observed that although glass fibres are inferior to carbon fibres in terms of mechanical properties however, the flexure strength and ILSS of glass based composites increases after texturing and were found closer to the properties of carbon based composites.     

Investigation on air texturing process for diacetate blending with polyester filaments

Influences of processing parameters on tensile property, stability and bulk of core-and-effect air textured yarns of diacetate and polyester filaments are mainly examined in this paper. When the air pressure is raised, the tenacity and breaking elongation of textured yarns are reduced, Instability I and II tend to decrease at first and then increase, the core bulk declines markedly at first and then changes slowly, whereas the overall bulk changes little at first and then goes up greatly. With increase in texturing speed, the yarn tenacity and breaking elongation both drop initially then begin to increase, the core bulk and overall bulk are almost linearly increased, while the yarn instability changes with an unclear trend. When the winding underfeed ratio is increased, the yarn tenacity, breaking elongation and core bulk are reduced, but the yarn stability is slightly improved. The wetting of the core component produces higher tenacity, breaking elongation, instability and bulk, compared with that of the effect component or that of both, but the difference is insignificant.     

Properties of core-and-effect air textured yarns blended by diacetate and polyester filaments

In present work, PET FDY has been used to blend with diacetate filaments by air texturing process and core-and-effect air-textured yarns have been produced. The influences of both over-feeds of core and effect components on properties of textured yarns were mainly examined. It was observed that a spun-like effect of diacetate filaments occurred during air texturing and there were a little amount of free fiber ends besides loops on blended air textured yarns, while the number of free fiber ends changed little with variation in over-feeds. The tenacity of textured yarns decreased with increase in over-feeds of effect or core component. The breaking elongation increased with increase in over-feed of effect component, but decreased with increase in over-feed of core component. The yarn stability improves when both over-feeds are increased. The effect of over-feeds on boiling water shrinkage shows no clear trend. The core and average diameters are higher at high over-feed of effect component, but the over-feed of core component exhibits little effect on yarn diameters. The number and size of loops are increase with increased over-feed of effect component.     

The effect of spinning parameters on mechanical and physical properties of core-spun yarns produced by the three-strand modified method (TSMM)

The effect of spinning parameters on core-spun yarns properties manufactured using three-strand modified method (TSMM) was analyzed. Of the various spinning parameters, strand spacing, yarn linear density and yarn twist have a crucial effect on core-spun yarn properties. To achieve the objectives of this research, general physical properties of core-spun yarns together with existing standards were thoroughly studied. First of all, the strand spacing and yarn linear density were optimized. Afterwards, the effects of variation of yarn twist and sheath roving linear density on core-spun yarns properties were investigated. Finally, the physical and mechanical properties of TSMM yarns were compared with those of siro and conventional ring core-spun yarns counterparts. It was found that, the best strand spacing and yarn linear density to produce core-spun yarns are 8 mm and 45 tex, respectively. Results showed that, tenacity of TSMM yarns increases up to a certain twist level beyond which it reduces. The result confirmed that 45 tex yarns produced by three rovings of the same count are superior with regards to tenacity and hairiness. The optimized yarns produced by three-strand modified method enjoy superior physical and mechanical properties in comparison to the ring and siro core-spun yarns.     

Effect of opening roller speed, drums speed difference and suction air pressure on properties of open-end friction spun polyester and acrylic yarns

The present paper is concerned with the influence of opening roller speed, drum speed difference and suction air pressure on properties of polyester and acrylic open-end friction spun yarns. The results shows that the opening roller speed and the suction air pressure have considerable influence on the characteristics of polyester and acrylic open-end friction spun yarns. In case of polyester yarns the unevenness, imperfection and hairiness decreases and the yarn tenacity increases with the increase in opening roller speed and suction air pressure. However for acrylic yarns the unevenness and imperfections decreases and tenacity increases with the increase in opening roller speed and suction air pressure.     

Dynamic friction of polyester air-jet textured yarns

In this paper, friction of air-jet textured yarns is investigated. Using a friction measuring apparatus fabricated in-house, dynamic friction forces of the yarns under yarn-to-metal (YM) and yarn-to-yarn (YY) rubbing modes are measured. The influence of processing variables of air-jet texturing viz., overfeed, air pressure, dry/wet texturing and normal/core-and-effect texturing on dynamic friction is analysed. The results indicate that friction force increases with increasing rubbing speeds and yarn input tension. YM dynamic friction decreases initially and then starts to increase at higher overfeeds. YY dynamic friction increases with increasing overfeed. YM dynamic friction decreases with an increase in air pressure while an opposite trend is observed for YY friction. Wet textured yarns have higher friction than dry textured yarns. Core wetted core-and-effect textured yarns have higher friction than normal textured yarns.     

Effect of fibre cross-sectional shape on the properties of POY continuous filaments yarns

There are various structural parameters (number of filament, cross-sectional shape, linear density, etc.) determined during the production of synthetic fibre and these parameters influence product features. Among these parameters, cross-sectional shape of fibres has a significant importance. Desired features can be added to the products by varying the cross-sectional shape and in this way; new products with improved features or with high added value can be produced. As a consequence, studies on this subject have increased recently. In this study, the effects of different cross-sectional shapes and yarn linear density on the features of polyester partially oriented yarn (POY) have been investigated. Five different cross-sectional shapes named round, trilobal, tetra, hexsa and octolobal and two different linear densities have been used in the study. Tenacity-elongation and unevenness tests have been applied onto yarns. As a result of the study, it was seen that round, tetra and octolobal cross-sectional shapes lead to production of yarn with high tenacity and breaking elongation while trilobal and hexsa leads to production of yarn with low tenacity. In addition, due to its deep-channelled structure, hexsa crosssectional shape led to POY yarn structure with a high unevenness rate. It was also seen that an increase in the rate of linear density decreased the tenacity and breaking elongation rates of yarn and reduced POY unevenness.     

Influence of the core-sheath weight ratio and twist on the tensile strength of the ring core yarns with high tenacity filaments

Core spun yarns are applied for various purposes that especially require the multi-functional performance. This research reports on the core spinning effect on the yarn strength. We prepared various core yarns by combining different kinds of high tenacity filaments in core with cotton staples in sheath with various twist levels in the ring spin system. And the tensile strength was tested to investigate the contribution of the core-sheath structure to the core yarn strength. The influence of the twist level was also checked up on the relationship between the core-sheath structure and the yarn strength. Results turned out that the core-sheath weight ratio had influence on the tensile properties of the ring core-spun yarns in different ways according to the core filaments used for the yarn. Increasing the twists yielded a monotone decreasing strength for the aramid and the basalt core yarns, while the PET core yarns showed almost unchanged strength, which could be ascribed to the extensional property of the filaments.     

Effect of strand spacing and twist multiplier on structural and mechanical properties of Siro-spun yarns

The effect of strand spacing and twist multiplier on strength of Siro-spun yarns with reference to the yarn structural parameters was investigated. Of the various structural parameters for staple yarns, fiber migration has a crucial influence on the yarn strength, which in turn to a considerable extent is influenced by the strand spacing and twist multiplier. Achieving the objectives of this research, the yarns were produced from lyocell fibers at five strand spacings and four different twist multipliers. Tracer fiber technique combined with image analysis were utilized to study the yarn migration parameters. Afterwards, the yarns were subjected to uniaxial loading by a CRE tensile tester. The measured results are presented in forms of diagrams and tables. The findings reveal that, as strand spacing is increased, yarn tenacity increases up to strand spacing of 8 mm beyond which it reduces. Analysis of the results indicates that the higher tenacity values at the strand spacing of 8 mm can be attributed to the higher mean fiber position, higher migration factor, higher proportion of broken fibers and lower hairiness.     

The effect of the processing factors on the physical properties of high shrinkable nylon composite yarns

This paper is aiming to develop high shrinkable differential shrinkage and mixed fibre nylon composite yarns by applying the high shrinkable polyester manufacturing technology. The wet and dry thermal shrinkages and mechanical properties of developed nylon composite yarns are measured and discussed with processing factors in the spinning and texturing processes. And the effects of the processing factors on the physical properties of high shrinkable nylon composite yarns are investigated. For this purpose, twenty seven nylon 30d/12f SDY were prepared with variation of spinning temperature, 2nd godet roller temperature and draw ratio on the spinning machine. The optimum spinning condition which showed maximum wet thermal shrinkage and stress was determined and high shrinkable nylon 30d/12f SDY spun under this optimum condition used as a core and three kinds of regular nylon filaments used as sheath were processed on the texturing machine with variation of 1st and 2nd heater temperatures. The optimum texturing process condition was decided through analysis of dry thermal shrinkage of these core and sheath nylon filaments. Finally, high shrinkable differential shrinkage and mixed fibre nylon composite yarns were made under the optimum texturing condition on the texturing machine, its wet thermal shrinkage was 13.8 %, which was much more higher than that of regular nylon composite yarns. The differential shrinkage effect of the developed nylon composite yarns was found in the yarn surface and cross section profiles by microscope and SEM.     

Study on the static and dynamic strengths and weavability of spun yarns

This study reports on the analysis of tenacity and breaking elongation of ring-, rotor- and air-jet-polyester/viscose spun yarns measured using static- and dynamic tensile testers. The weavability, a measure of performance of these yarns in post spinning operations is quantified. The yarn diameters and helix angles of fibres in these yarns are measured in order to analyze the effect of types of spun yarn and blend proportion on yarn elongations. The dynamic tenacity is highly correlated with the weavability than the average static tenacity measured at 500 mm gauge length. The minimum static tenacity obtained from 100 tests has high correlation with the dynamic tenacity. The present study indicates that it is appropriate to evaluate the performance of spun yarns in winding, warping and weaving based on the dynamic yarn tenacity measured while running a 200 m length of yarn in a constant tension transport tester or the minimum static yarn tenacity obtained using any conventional constant rate extension (CRE) tensile testers corresponding to a total test length of 50 m.     

Assessment of color strength and color difference values of polyester fabrics containing continuous weft yarns after abrasion

This paper assesses the color difference and color strength values (K/S) obtained for eight disperse-dyed polyester fabric samples with different fabric construction parameters (weft yarn type, weft yarn count, weft density and fabric weave) after four sets of abrasion cycles. Warp yarn type and count, warp density, and warp yarn twist are the same for all fabrics. Fabric samples are dyed in a commercial red disperse dye (C.I. Disperse Red 74:1) and four different abrasion cycles (2500, 5000, 7500, 10000) are used. TheK/S values of the abraided fabrics and color difference values between the control fabric (dyed but not abraided) and abraded fabrics are calculated. The main differences in theK/S and color difference values are observed between 0–2500 abrasion cycles. The high tenacity of the polyester fibers and continuous polyester yarns causes some fuzz but no pilling formation on the fabric surface that lead to increasedK/S values and color differences. Fiber dullness, yarn thickness, yarn density and fabric weave are concluded to have different effects on the appearance after abrasion.     

Moisture and thermal permeability of the hollow textured PET imbedded woven fabrics for high emotional garments

This study examined the effects of the total porosity, pore size, and cover factor on the moisture and thermal permeability of woven fabrics made from DTY (draw textured yarns) and ATY (air jet textured yarns) composite yarns with hollow PET (polyethylene terephthalate) yarns. The wicking of the hollow composite yarn fabrics was found to be superior to that of the high twisted yarn fabrics, which may be due to the high porosity in the hollow composites yarns, but this was not related to the cover factor. The drying characteristics of the hollow composite yarn fabric with high porosity were inferior compared to the high twisted yarn fabrics due to the large amounts of liquid water in the large pores, which resulted in a longer drying time of the fabric. The thermal conductivity of the hollow composite yarn fabrics decreased with increasing measured pore diameter due to the bulky yarn structure. The effects of the hollowness of the yarn on the thermal conductivity were more dominant than those of the yarn structural parameters. The air permeability increased with increasing measured pore diameter but the effects of the cover factor on the air permeability were not observed in the hollow composite yarn fabrics. The effects of porosity on the moisture and thermal permeability of the woven fabrics made from the hollow composite filaments were found to be critical, i.e., wicking and air permeability increase with increasing porosity. In addition, the drying rate increased with increasing porosity and the thermal conductivity decreased with increasing pore diameter, but were independent of the cover factor.     

Effect of blends proportion on the characteristics of dry and Pre-wet nylon/viscose blended air-jet textured yarns

Blending of nylon filament with viscose can overcome the drawbacks of these yarns. Thermoplastic and thermoset filament yarns can be blended in air-jet texturising method. The characteristics of nylon/viscose blended filament yarns are required to be understood in order to convert them in to useful products. Therefore, nylon/viscose blended yarns in different proportions were produced using nylon 6 and viscose filament yarns in air jet texturising machine. The textured yarns were also produced in dry and pre-wet conditions to understand the effect of water on textured yarn characteristics. It was found that the loops frequency, bulkiness of nylon/viscose blended textured yarns increase with increase in viscose proportion. The Loops stability, tenacity and breaking elongation decrease with increase in viscose proportion. Pre-wet textured yarn show higher loops, bulkiness, and good loop stability than their corresponding dry textured yarns.     

A comparison between the thermomechanical and structural changes in textured PET yarns after superheated steam and dry heat treatment

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at 200 °C. The time dependence of the properties was not linear.     

Effect of weaving process on tensile characterization of single and multiple ends of air-entangled textured polyester yarns

The tensile properties of air-entangled textured polyester single and multiple yarn ends before and after weaving were analyzed. The effects of weaving process considering fabric unit cell interlacement and number of yarn ends were evaluated by regression model. For this purpose, plain, ribs and satin woven fabrics were produced. The yarns were raveled from fabrics, and the tensile tests were applied to these yarns. The developed regression model showed that the number of interlacement and crimp ratio on the warp and weft yarns influence their tensile strength. Tensile strength of raveled yarns decreased compared to that of the bobbin yarn due to the effect of weaving process. This property degradation on the ravel yarns considered process degradation. Generally, when the number of warp and weft yarn ends increases, the warp and weft yarn tensile strengths for each fabric type decrease, whereas the warp and weft yarn tensile elongations slightly increase. The results from regression model were compared with the measured values. This study confirmed that the method in the study can be a viable and reliable tool. The research finding could be useful those who work on preform fabrication.     

Investigation of Parameters for Preparing Nanofiber Yarn via a Stepped Airflow-assisted Electrospinning

Electrospinning is a simple and cost-effective method to prepare fiber with nanometer scale. More importantly, 3D flexible nanofiber yarns that fabricated by electrospinning have shown excellent application prospects in smart textiles, wearable sensors, energy storage devices, tissue engineering, and so on. However, current methods for preparing electrospinning nanofiber yarns had some limitations, including low yarn yield and poor yarn structure. In this paper, a stepped airflow-assisted electrospinning method was designed to prepare continuously twisted nanofiber yarn through introducing stepped airflow into traditional electrospinning system. The stepped airflow could not only help to improve nanofiber yield, but also good for controlling the formed nanofibers to be deposited in a small area. In addition, the experimental methods of single factor variables were used to study the effects of stepped airflow pressure, applied voltage, spinning distance, solution flow rate, air pumping volume and friction roller speed on nanofiber yarn yield, nanofiber diameter, yarn twist and mechanical property. The results showed that prepared nanofiber yarns exhibited perfect morphologies and the yield of nanofiber yarn could reach to a maximum of 4.207 g/h. The breaking strength and elongation at break of the prepared yarn could reach to 23.52 MPa and 30.61 %, respectively.     

A novel method to reduce hairiness level of ring spun yarn

The quality of ring spun yarns is largely determined by its level of hairiness. The existence of hairiness inevitably affects the quality of ring spun yarns. This paper presents an innovative method on lowering the level of hairiness of ring spun yarns. This can be achieved by shooting compressed air to the yarn, through a swirl nozzle comprising a yarn duct and an airjet nozzle attached to a traditional ring spin frame. When compressed air is applied from the air-jet nozzle to the yarn duct, the swirling air flow tucks surface fibers of the ring spun yarns into its body. Four controllable variable parameters for the process, supplied pressure, nozzle position, twist factor and spindle speed, and their effects on the lowering of yarn hairiness will be clarified. Their impact on the quality of the yarn is statistically analyzed, and the optimum outcome of the combination of parameters for the process, will thus be determined.     

A theoretical investigation on the generation of strength in staple yarns

In this article, an attempt has been made to explain the failure mechanism of spun yarns. The mechanism includes the aspects of generation and distribution of forces on a fibre under the tensile loading of a yarn, the free body diagram of forces, the conditions for gripping and slipping of a fibre, and the initiation, propagation, and ultimate yarn rupture in its weakest link. A simple mathematical model for the tenacity of spun yarns has been proposed. The model is based on the translation of fibre bundle tenacity into the yarn tenacity.