Study on thermal and evaporative resistances of multilayered fabric ensembles

The present work deals with the study on thermal and evaporative resistance of multilayered fabric ensembles meant for cold weather applications. Three-layered structure is used to study the thermal comfort properties. Knitted fabric and polytetrafluoroethylene coated fabrics were used in inner and outer layer, respectively. Needle punched fabrics produced from polyester fibre were used in middle layer. Fifteen different non-woven fabrics were produced according to Box and Behnken experimental design for three variables and three levels by varying mass per unit area, punch density and depth of needle penetration. The produced fabrics were evaluated for thermal and evaporative resistances with and without inner and outer layer fabrics. Thickness, air permeability, bulk density and porosity of the needle punched fabrics were studied. The properties of the fabrics were analyzed for statistical significance by using ‘Design-Expert’ statistical software. Artificial neural network model was developed to predict the properties of fabrics and validation of model was done with the testing data-set. The performance of prediction was evaluated by mean square error, mean absolute error percentage and correlation coefficient. It was concluded that the predicted properties of fabric correlated well with the experimental results.     

Study of stiffness and abrasion resistance of needle‐punched nonwoven blankets

The properties of needled fabrics depend on the nature of component fibers and the manner in which fibers are arranged in the structure. Fiber properties along with the various machine and web parameters contribute to the structure that emerges from the needling operation. In this paper, the effect of machine parameters such as depth of needle penetration and punch density on fabric stiffness and abrasion resistance of needled blankets has been studied. The effect of calendering and sandwiching hollow polyester fibers between two layers of fine polyester fibers on the abrasion resistance and fabric stiffness has also been studied. It was observed that fabric stiffness first increases and then decreases as the depth of needle penetration increases. Increase in punch density leads to a decrease in fabric stiffness only at higher levels of depth of penetration due to fiber rupture. Calendering improves the fabric abrasion resistance properties but fabric stiffness also increases. Sandwiching of hollow polyester fibers between the two layers of fine denier polyester fibers improves the abrasion resistance without increasing the fabric stiffness.     

Study on needle‐punched nonwoven fabrics made from shrinkable and non‐shrinkable acrylic blends. Part III: filtration characteristics

This paper reports the filtration behaviours of needle‐punched bulked nonwoven fabrics made from shrinkable and non‐shrinkable acrylic blends. The basic idea of the present work is to explore the possibility of structural changes in needle‐punched nonwoven fabrics made from blends of shrinkable and non‐shrinkable acrylic fibres, as in the case of an acrylic bulked yarn, to improve the filtration behaviour. In Part I and Part II of this series, compressional and transmission characteristics of these fabrics were reported, respectively. The effects of variables, namely fabric areal density, needle punch density and the proportion of shrinkable acrylic fibre in the blend, on various filtration‐related properties of needle‐punched nonwoven fabrics have been studied by relaxing the shrinkable component of the fabric using hot steam treatment. A three‐variable factorial design technique proposed by Box and Behnken was used to investigate the combined interaction effect of the above variables on the filtration properties of these fabrics. The fabric areal density and needle punch density were found to have a significant effect on filtration efficiency as well as pressure drop. The proportion of shrinkable acrylic fibre has little effect on filtration efficiency, but the trends are dependent on the needle punch density.     

Study on thermal resistance of multilayered fabrics under different compressional loads

In this work, the thermal resistance of multilayered fabric ensembles meant for cold weather conditions were studied under different compressional loads. An instrument has been developed to study the thermal resistance of fabrics under different compressional loads. The instrument consists of a test plate, guard plates and a bottom plate. The test plate and guard plates were assembled together as a single entity, which can be moved up and down with a screw shaft. A load cell was connected to the plate assembly to apply the required compressional load on the fabric specimen. Thermal resistance of multilayered fabrics was studied in the developed instrument under different loading conditions. Single-jersey knitted fabric, needle punched fabric and polytetraflouroethylene (PTFE) coated fabrics were used in the inner, middle and outer layer, respectively. Twenty different multilayered fabric ensembles with the same inner and outer layers were studied. The middle layers, i.e. needle punched nonwoven fabrics, were produced from polyester hollow fibres, with varying linear density of fibre, mass per unit area and punch density. The thermal resistance of multilayered fabrics obtained from the developed instrument was compared with the thermal resistance of instruments, namely sweating guarded hot plate (SGHP) and Alambeta. Regression equations were developed and the contour plots were drawn to analyse the effect of the fibre, fabric and process parameters. ANOVAs were conducted to find the significance of the compressional load, linear density of fibre, mass per unit area and punch density on the thermal resistance of fabrics. It was found that the thermal resistance obtained from the instrument follows the same trend as that of thermal resistance obtained from SGHP and Alambeta. Mass per unit area was found to have significant effect on the thermal resistance of multilayered fabrics under different compressional loads. The effect of punch density decreases with the increase in compressional load on the thermal resistance of multilayered fabrics. The thermal conductivity of multilayered fabrics was observed to increase with the increase in the compressional load.     

Study on Some Functional Properties of Mesta Needle Punched Nonwoven Fabrics Using Central Composite Rotatable Design

The combined effect of two structure forming process parameters i.e. punch density and needle penetration on properties of Mesta needle punched nonwoven fabric has been studied using central composite rotatable design. As properties are structure dependent, the relationship between compressional behavior and other functional properties was studied. It was observed that compressional (α) and recovery (β) parameters are well correlated with tensile, air permeability and thermal insulation value of Mesta needle punched fabric. The regression equations were also suggested. Therefore, the α and β may be used for indirect approximation of these properties with reasonable accuracy.     

Electrical resistance of jute needle-punched non-woven fabric – effect of punch density,needle penetration and area density

The electrical resistance of jute needle-punched non-woven fabric has been studied. Statistical model using central composite rotatable experimental design is developed for electrical resistance depending on the three important parameters of needled non-woven fabric, i.e. punch density, depth of needle penetration and mass per unit area. From this model and its contour diagrams, the effects of different parameters can be understood on electrical resistance of those fabrics. Prediction of electrical resistance can be made knowing the values of independent parameters. The correlation coefficients between observed and predicted values are found to be significant in all the cases. As depth of needle penetration increases for a particular punch density, electrical resistance increases and after reaching to maximum, it decreases having optimum at about 140 punches/cm² and 12?mm depth of needle penetration. With the increase of area density, resistance decreases. As punch density increases for a particular area density, resistance increases for high needle penetration.     

Study on needle punched jute nonwoven as an artificial medium for germination of seed: Effect of bulk density

A uniform, porous, and bulky mechanically entangled fibrous sheet, i.e., needle-punched nonwoven, from eco-friendly and natural, low-grade jute fiber, has been designed and engineered to use as an artificial medium for germination of seed in place of soil. Needle-punched nonwoven fabrics of different bulk densities have been prepared from low-grade jute. Bulk densities of needle punched nonwoven fabric can be changed due to change of punch density, area density and depth of needle penetration. In this case, bulk densities of fabric have been achieved by varying the punch densities only, keeping the area density and depth of needle penetration same/ unaltered. As per experimentation, 500 g/m² area density needle punched nonwoven with 0.116 g/cm³ bulk density shows the best quality of germination. This bulk density has been achieved using 160 punches/cm² and 13 mm depth of penetration as per the system applied and fiber used. It may be a good alternative as a medium of cultivation. The design of the bed is also proposed in the article. It is observed that in this artificial system, cultivation can be made in hostile condition and plant growth is better than that in soil. Its moisture-holding capacity and temperature control of medium help in better agriculture. This is highly applicable in the regions where soil is either not available or not suitable for cultivation.     

Investigation of electromagnetic shielding effectiveness of needle punched nonwoven fabrics with staple polypropylene and carbon fibres

Conductive needle punched nonwoven fabrics are developed from staple polypropylene (PP) and varying weight fractions (10, 20 and 30 wt.%) of staple carbon fibres. A fibrous webs of staple PP and carbon fibres were formed at a wool-type carding machine, and these webs subsequently bonded on needle punching machine with 132 punches/cm² and 13.5 mm needle penetration depth. The electromagnetic shielding effectiveness (EMSE), absorption and reflection characteristics of as-produced needle punched nonwoven fabrics were determined using a network analyser as specified in ASTM D4935-10 in the frequency range 15–3000 MHz. The surface resistivity measurements were carried out in accordance with ASTM D 257-07 standard. These results indicate that the EMSE values increase incrementally with frequency in the 15–3000 MHz range. The nonwoven sample with 30 wt.% carbon fibre showed the lowest surface resistivity of 3.348 kΩ and corresponding highest EMSE of ~42.1 dB in the 3000 MHz frequency range. In comparison, the highest EMSE values from 10 to 20 wt.% staple carbon fibre were found to be 15.6 and 32.2 dB in the 3000 MHz frequency, respectively. It was observed that the absorbance and reflectance curves of each nonwoven fabric move at opposite directions to each other. It was found that as the amount of carbon fibre in the nonwoven fabric increases, absorbance values decrease, but reflectance values increase. The resultant nonwoven fabric samples are expected to be used as garment interlining after thermal bonding and wall interlayer in the future.     

聚酰亚胺针刺布与聚苯硫醚针刺布的热稳定性与燃烧性能对比

本文采用热分析、极限氧指数、锥形量热法等手段来分析并对比了聚酰亚胺纤维（PI）针刺布与聚苯硫醚纤维（PPS）针刺布的热稳定性及燃烧性能。结果表明,PI与PPS针刺布的热分解温度分别为580℃和500℃,LOI分别为40%和35%,点燃时间分别为38s和32s,热释放速率最大值分别为62.6kW/m2和130.9kW/m2,烟指数分别为12MW/m2和35MW/m2。通过对比研究,得出PI针刺布比PPS针刺布具有更优异的热稳定性和燃烧性能。     

Sound and thermal insulation properties of flax/low melt PET needle punched nonwovens

Noise pollution is an ever increasing problem in the world because of the industrial revolution. Recently, researchers have begun investigating natural fiber composites as potential materials for the manufacture of sound absorption structures. In this work, flax/low melting point polyester needle punched nonwoven fabrics were manufactured and characterized for sound and thermal insulation applications. Nonwovens were developed by blending flax fibers with low melt PET at three blend ratios (10%, 20%, and 30%) with 7 mm and 10 mm needle penetration depth. The test results showed that there was a decrease in thermal resistance value with increase in low melt PET % and needle penetration depth. The developed nonwovens had better sound insulation value at medium and high frequency. There was no significant change in sound insulation value with increase in low melt PET %.     

19—A STUDY OF NEEDLED FABRICS. PART VI: THE MEASUREMENT OF PUNCHING FORCE DURING NEEDLING

An account is given of an investigation in which a small needle board was fitted to the compression cage of an Instron Tensile Tester and used to measure the forces developed during the penetration of a web by needles. The punching speeds were much lower than those in a needling machine. The effects of web weight, type of fibre, fibre length and fineness, density, a reinforcing base fabric, and punching speed were studied.     

Modeling of thermal properties of multilayered fabrics by ANN consisting of polypropylene needle-punched nonwovens

This paper presents the prediction of thermal and evaporative resistances of multilayered fabrics meant for cold weather conditions using artificial neural network (ANN) model. Thermal and evaporative resistances of fabrics were evaluated using sweating guarded hot plate method. The significance and interdependency of thickness on other fabric and process parameters and its effect on prediction performance of ANN model is analyzed in detail. For this purpose, two different network architectures were used to predict the thermal properties of multilayered fabrics. In both the networks, three-layer structure consisting of input, hidden and output layers was used. First, network was constructed with four input parameters, namely linear density of fiber, mass per unit area, punch density, and thickness of nonwoven fabric which predicts thermal and evaporative resistances. Second network was made with three input parameters, namely linear density, mass per unit area, and punch density. The network parameters were optimized to give minimum mean square error (MSE), mean absolute error percentage, and good correlation coefficient. The trend analysis was conducted and influence of various input parameters on the thermal properties of multilayered fabrics was studied. The significance of each input parameter in the prediction of thermal properties was studied by carrying out sensitivity analysis. The mean square error of the test dataset before and after the exclusion of the corresponding input parameter is taken for analysis. The input parameters were ranked based on the MSE ratio of test dataset. The predicted thermal properties of multilayered fabrics are correlated well with the experimental values. It was observed that the ANN model with minimum input parameters, namely linear density of fiber, mass per unit area, and punch density can predict the thermal properties of multilayered fabrics with good accuracy.     

Investigation of electromagnetic shielding effectiveness of needle punched nonwoven fabric produced from conductive silver coated staple polyamide fibre

In this paper, electromagnetic shielding effectiveness (EMSE) of needle-punched nonwoven fabric produced from silver-coated staple polyamide fibre having a fineness of 1.7 dtex was investigated. This production was carried out at Automatex needle punching line, which consists of carding, cross lapper and needle punching machine. After production, the surface resistivity measurements of needle-punched nonwoven fabric was carried out in accordance with ASTM D 257-07 standard. The EMSE of the as-produced needle-punched nonwoven fabric was determined using a network analyzer as specified in ASTM D4935-10 in the frequency range of 15–3000 MHz. Electromagnetic shielding test shows that needle-punched nonwoven fabric produced from 1.7-dtex silver-coated polyamide fibre has the highest shielding value of 36.53 dB in the frequency range of 15–3000 MHz. The EMSE of needle-punched nonwoven fabric with fibre fineness of 1.7 dtex increased from 11.00 dB maximum to 36.53 dB in the 15–3000 MHz frequency range. It was seen that as the frequency increases, reflection values of the needle-punched nonwoven fabric decrease at floating mode, while absorption values of the nonwoven fabric increase at floating mode in the frequency range of 15–3000 MHz. EMSE results of the needle-punched nonwoven fabric produced from 1.7-dtex silver-coated staple polyamide fibres were compared to carbon fabric and needle-punched nonwoven fabric made from stainless steel fibres.     

Investigation on filtration properties of polyester needle-punched dust filter

Abstract

In nonwoven filter fabrics, virgin polyester fibre is mostly used. Therefore, this study has been conducted with the use of virgin polyester fibre and recycled polyester fibre which is obtained after recycling of post-consumer bottle flakes to reduce the cost of filter fabric. The study is concerned to examine the effect of fabric GSM (grams/m²), needling density and depth of needle penetration on filtration efficiency and also to see the suitability of recycled polyester fibre in place of virgin polyester fibre. The study has shown that the increase in fabric weight resulted in increase in the filtration efficiency percentage. The increase in the depth of needle penetration resulted in increase in the extent of filtration efficiency initially; subsequently, it decreased. Similar trends were observed in case of both recycled polyester filter fabrics and virgin polyester filter fabrics. Though the filtration efficiency of filter fabrics prepared from virgin polyester fibre was slightly higher, the filtration efficiency of fabrics prepared from recycled polyester fibre was lower by only 2 to 3 per cent due to close difference in values of molecular weight (Mw) and polydispersity index (PDI). Therefore, looking to the filtration efficiency percentage, it may be suggested that recycled polyester fibre can be used in place of virgin polyester fibre for the manufacturing of needle-punched nonwoven filter fabrics.     

层压对非织造布热舒适性的影响

对于一定面密度的针刺非织造布,其热性能即绝热值和热阻值会随着层数的增加得到明显的改善,但层压后织物的冷暖感值是保持不变的。针板上刺针排列方式的设计在多层结构的成型过程中,对水蒸气的传输速率起着重要的作用。多层层压对织物的厚度也有很大的影响。     

针刺工艺参数对非织造布性能的影响

针刺非织造布是非织造产品中发展较快的产品之一。本文探讨了两种主要的针刺工艺参数对非织造布各项性能的影响。经实验验证及理论分析 ,得出了针刺密度、针刺深度与非织造布物理性能、机械性能及过滤性能的关系     

Modelling of thermal conductivity of knitted fabrics made of cotton–bamboo yarns using artificial neural network

Regenerated cellulosic fibre made from bamboo is gaining popularity for apparel use due to its improved functional properties. This paper presents the modelling of thermal conductivity of knitted fabrics made from blended yarns of cotton and bamboo fibres using an artificial neural network (ANN). Five parameters, namely knitted fabric structure type, yarn linear density, bamboo fibre proportion (%), fabric thickness and fabric areal density, were used as inputs to the ANN model. The developed model was able to predict the thermal conductivity of fabrics with very good accuracy. The trend analysis of the developed model revealed the influence of various input parameters on the thermal conductivity of knitted fabrics. These findings can be judiciously used for the selection of optimum material and structural parameters of knitted cellulosic fabrics for a particular end‐use.     

Role of stuffer layers and fibre volume fractions on the mechanical properties of 3D woven fabrics for structural composites applications

Using weaving technology, possible manipulations can be done so as to derive maximum advantage from the reinforcements towards desired mechanical properties of the composites. Thus with different sets of weaving parameters and tow linear densities, an attempt has been made to investigate tensile, impact and knife penetration performance of different stuffer layers and fibre volume fractions of 3D orthogonal and interlock E-glass fabrics as reinforcements for composite applications. The tensile properties were effectively influenced by warp tow crimp%, number of stuffer tows per unit width of the fabric and fabric assistance. The tow linear density, fabric sett and the number of cross over points play a determining role towards impact energy absorption capacity. The fabric sett along with tow linear densities also play a vital role towards peak energy during knife penetration test. The number of cross over points were found to be least important in the knife penetration results analysis.     

Application of artificial neural network (ANN) for the prediction of thermal resistance of knitted fabrics at different moisture content*

Thermal resistance of the fabrics is one of the decisive parameters in terms of comfort; however it can change due to wetting. Therefore, thermal resistance of wetted fabric is important for comfort performance of garments. In recent years, artificial neural networks (ANN) have been used in the textile field for classification, identification, prediction of properties and optimization problems. ANNs can predict the fabric thermal properties by considering the influence of all fabric parameters at the same time. In this study, ANNs were used to predict thermal resistance of wetted fabrics. For this aim, two different architectures were experienced and high regression coefficient (R²) between the predicted (training and testing) and observed thermal resistance values were obtained from both models. The obtained regression coefficient values were over 90% for both models. Then it can be said that ANNs could be used for predicting thermal resistance of wetted fabrics successfully.     

玻璃纤维滤材的发展及玻璃纤维针刺毡的加工技术

平幅布、膨体布和针刺毡是目前国内市场上主要使用的三大系列玻纤滤材 ,高效高性能滤材、超高温滤材和触媒涂层滤材是国际上过滤材料的发展趋势。文章还介绍了玻纤针刺毡的原料选用、生产工艺以及产品性能、用途和标准。