Nonwoven fabric/spacer fabric/polyurethane foam composites: Physical and mechanical evaluations

In the first stage, polyethylene terephthalate (PET) fibers and Kevlar fibers are combined at a blending ratio of 80/ 20 wt% in order to form PET/Kevlar nonwoven fabrics. Two pieces of PET/Kevlar nonwoven fabrics that enclose a carbonfiber (CF) interlayer are then needle punched in order to form PET/Kevlar/CF (PKC) composites. In the second stage, the sandwiches compose PKC composites as the top and the bottom layers, as well as an interlayer that is composed of a spacer fabric and polyurethane (PU) foam. PU foams have different densities of 200, 210, 220, 230, and 240 kg/m³. These resulting nonwoven fabric/spacer fabric/PU foam sandwiches are then tested using a drop-weight impact test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that the optimal properties of sandwiches occur with their corresponding PU foam density as follows: an optimal residual stress (240 kg/m³), an optimal compressive strength (240 kg/m³), and an optimal bursting strength (220 kg/m³). In addition, the sandwiches reach the HF1 level according to the horizontal burning test results. They also have an average electromagnetic interference shielding effectiveness of -48 dB, as well as a sound absorption coefficient of 0.5 in a frequency between 1500-2500 Hz, which indicates a satisfactory sound absorption effect. The nonwoven fabric/spacer fabric/PU foam sandwiches proposed in this study are mechanically strong, sound absorbent, and fire retardant, and can be used in construction material and electromagnetic shielding composites.     

Electromagnetic interference shielding effectiveness of SS/PET hybrid yarn incorporated woven fabrics

A detailed study of electromagnetic shielding effectiveness (EMSE) of woven fabrics made of polyester and stainless steel/polyester blended conductive yarn was presented in this research work. Fabrics with different structures were analyzed and their shielding behavior was reported under different frequencies. Shielding efficiency of fabric was analyzed by vector network analyzer in the frequency range of 300 kHz to 1.5 GHz using coaxial transmission line holder. The effects of different fabric parameters such as weft density, proportion of conductive weft yarn, proportion of stainless steel content, grid openness, weave pattern and number of fabric layers on EMSE of fabrics were studied. The EMSE of fabric was found to be increased with increase in proportion of conductive yarn in the weft way. With increase in overall stainless-steel content in the fabric, the EMSE of fabric was increased. As such weave is considered, it did not have significant effect on EMSE of fabrics. But fabric with lower openness and aperture ratio showed better conducting network, hence better shielding. With increase in number of layers of fabric and ply yarns, EMSE of fabric was increased.     

Sound absorbent,flame retardant warp knitting spacer fabrics: Manufacturing techniques and characterization evaluations

This study proposes a combination for reciprocal reinforcement between warp knitting spacer fabrics and PU foams. PET/Kevlar nonwoven fabrics are made with an 80:20 ratio and an incorporation of various needle-punching speed of 100, 150, 200, 250, and 300 needles/min. Ascribing to having an optimal bursting strength, sound absorption coefficient, and limited oxygen index (LOI), the PET/Kevlar nonwoven fabric that is made by 200 needles/min are selected to be combined with a glass-fiber fabric by applying needle punch in order to form a surface layer. Next, warp knitting spacer fabrics and the nonwoven fabrics are laminated, followed by being combined with polyurethane (PU) foam that are featured with different densities of 200, 210, 220, 230, and 240 kg/m³ in order to form spacer fabric/PU foam composites with multiple functions. The composites are then tested with a drop-weight test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that all spacer fabric/PU foam composites reach a horizontal burning level of HF1, and their sound absorption coefficients at 2500-4000 Hz also suggest a satisfactory sound absorption. In particular, the optimal residual stress and compressive strength are present when the composites contain 210 kg/m³ PU foam. Similarly, the optimal bursting strength of the composites occurs when they are composed of 230 kg/m³ PU foam. The spacer fabric/PU foam composites are proven to have high strengths, sound absorption, and fire retardant, and thus have promising potentials for use as construction materials and light weight composite planks.     

Development of Multilayered Nanocomposites for Applications in Personal Protection

The aim of the presented research was to study the influence of surface layer material on improvement of impact, dielectric, EMI shielding and sound absorption properties of sandwich composites. The sandwich composite structure consisted of Kevlar or Carbon woven fabric at the surface layer, recycled high loft nonwoven in the center and a mixture of carbon particles/epoxy matrix as a binder to hold the surface layer and core together. The carbon particles were incorporated in epoxy in order to improve failure mechanism and enhance dielectric properties or electromagnetic shielding of sandwich composites. The biggest improvements on impact properties of sandwich composites were obtained when Kevlar fabric was used as surface layer. However, surface layer of carbon fabric was found to provide better dielectric properties and improve EMI shielding of sandwich composites against Kevlar fabric surface layer.     

Improving the impact resistance of p-aramid fabrics by sequential impregnation with shear thickening fluid

A simple and effective method for impregnation of p-aramid (Kevlar^®) fabric with shear thickening fluid (STF) has been developed in this research. Kevlar fabric was impregnated with STF in two stages in a sequential manner. Three levels of pressure (0.5, 1 and 2 bar) were used in each stage of impregnation. It was observed that impact energy absorption by Kevlar fabrics, impregnated with STF in this newly developed method, increased significantly as compared to untreated Kevlar fabrics and Kevlar fabrics treated with STF in conventional way (single step impregnation). Better results were obtained when the first impregnation pressure was higher than that of the second, even with same combination of pressures. Such fabrics also showed a much higher STF add-on (~18 %) as compared to that of fabrics impregnated in single step (3-5 %). Low velocity ballistic tests also confirmed the advantages of the new method as sequentially impregnated fabric showed 124.8 % and 24.4 % increase in impact energy absorption compared to untreated and STF impregnated Kevlar fabrics in single step, respectively.     

Study on anisotropic creep behavior of nonwoven geotextiles

The anisotropy in creep behavior of two types of nonwoven fabrics (needle-punched and thermobonded spun laid) has been studied. It has been observed that the amount of time dependent extension depends on the direction, amount of loading and the structure of nonwoven the fabrics. The time dependent extension (creep) for the nonwoven fabric increases with the increase in amount of load. The higher initial extension and creep are observed for needle-punched nonwoven fabric as compared to thermobonded spun-laid nonwoven fabric. The creep behavior of needle-punched nonwoven shows a logarithmic relationship with time, but the thermobonded spun-laid nonwoven fabric does not show such logarithmic relationship. For a particular fabric, the creep is dependent on the fiber arrangement and is minimum in the direction in which the proportion of fiber is maximum and visa versa.     

Sound absorption and viscoelastic property of acoustical automotive nonwovens and their plasma treatment

Sound absorption property, viscoelastic property and the effect of plasma treatment of four automotive nonwoven fabrics on these properties are discussed in this research paper. Needle-punched fabrics used for vehicle headliner include 2 polyester fabrics made of hollow polyester fibers or solid polyester fibers, and 2 polypropylene-composite cellulose fabrics made of jute fibers or kenaf fibers, manufactured with the same web structure of apparent fabric density and fabric thickness. Hollow polyester fiber fabric has the highest sound absorption and the highest loss factor, the second highest is jute fiber fabric. The viscoelastic property is found to be related to the sound absorption property of fabric. The plasma treatment on nonwoven fabrics changes their sound absorption and viscoelastic property as well as their fabric weight and pore size. Hollow polyester fabric shows the increased sound absorption and viscoelastic property after the treatment with the increased pore sizes, while regular polyester fabric displays insignificant changes. The cellulose fabrics are more affected by plasma treatment compared to the polyester fabrics in terms of fabric weight loss and pore size, and jute fabric is more affected than kenaf fabric due to fiber weakness. The jute fabric demonstrates the decreased sound absorption and viscoelastic property, while kenaf fabric shows the increased sound absorption with the unchanged viscoelastic property after the treatment.     

An investigation in structural parameters of needle-punched nonwoven fabrics on their thermal insulation property

The thermal characteristics of hollow polyester fibers were compared with solid polyester fibers in order to study their processing behavior and performance characteristics. The effects of different processing and structural properties including fiber diameter, bulk density of layer, and surface pressure on layers of needle-punched nonwoven fabrics with hollow fibers on thermal resistance properties were also investigated. The results show that hollow fibers have a higher thermal resistance in comparison with solid ones. This is a consequence of air trapping inside the fibers, higher bulkiness, and higher surface area of hollow fibers. Furthermore, thermal resistance of microfibers is better than those of macrofibers in both hollow and solid fibers. The thermal resistance of nonwoven subjected to this study, have an inverted-U-shaped pattern versus the bulk density of the fabric. The results also showed that thermal resistance of needle-punched nonwoven fabrics can be affected by the range of heater temperature during the test, however considerably can be affected by fabric thickness as a main structural property of nonwoven fabrics.     

Process technology and performance evaluation of functional knee pad

In this study, Polylactic Acid (PLA) nonwoven fabric and thermoplastic polyurethane (TPU) honeycomb air cushion (TPU-HAC) were employed to form an impact resistant layer for functional knee pads. PLA nonwoven fabric has low manufacture cost and flexibility of the honeycomb air cushion improved the quality of functional knee pad sold in the market. This study focused on the strength of PLA nonwovens and the impact resistance of TPU honeycomb air pads. The PLA fibers and low-melting-point (low-Tm) PLA fibers are used as raw materials to fabricate PLA nonwoven fabric. The PLA fibers and low-melting-point PLA fibers were mixed at weight ratios of 10, 20, 30, 40, and 50 %. PLA nonwoven fabric and TPU-HAC materials were combined in a sandwich structure to protect against impact. Impact resistance was evaluated using a falling-weight impact-resistance machine. Experimental findings indicate that changing various layers can improve the impact resistance of the sandwich structure of the TPU-HAC materials. A TPU-HAC layer with a thickness of 2/8/10 mm optimized the impact resistance. In 25 J falling-weight impact test, the TPU-HAC layer 2/8/10 mm provides an impact resistance of 2932 N; the PLA/TPU-HAC composite had the best impact resistance; 2516 N. PLA nonwoven fabric had the best mechanical properties with low-Tm PLA fibers at 30 % weight. The impact resistance achieved using above combination of materials met the level 2, range 3 impact values mentioned in EN 14120 standards.     

The modelling of electrical resistance regarding PES nonwoven conveyor belts with conductive PA6 fibers

This paper reports the results from the modelling of electrical resistance of polyester reinforced nonwoven fabrics used for light conveyor belts having conductive PA6 fibres and the same value of fabric volume fraction. The modelling was carried out on the basis of nonwoven construction parameters (the content of conductive fibres in nonwoven layers, fabric thickness), a two-probe method of electrical resistance measurement using flat electrodes and common ohmmeter, and a deterministic modelling method, e.g. statistical factor analysis. The results show very good agreement between the experimental and predicted values of conveyor belts’ electrical resistance. The proposed model provides guidelines for the engineering of conveyor belts in order to fit the prescribed electrical resistance.     

Studies on compression behaviour of polypropylene needle punched nonwoven fabrics under wet condition

The present study deals with the effect of parallel-laid and cross-laid web of polypropylene needle punched nonwoven fabrics on compression properties (initial thickness, percentage compression, percentage thickness loss and percentage compression resilience) under wet condition. These compression properties of polypropylene needle-punched nonwoven under wet condition have also been compared with its dry condition. With the increase in needling density the initial thickness, percentage compression and percentage thickness loss of the fabrics under wet condition decrease to higher extent compared to its dry condition both in case of parallel-laid and cross-laid fabrics. Cross-laid nonwoven fabric presents lower value of initial thickness percentage compression and thickness loss compared to parallel-laid fabric which is very prominent at high needling density (350 punches/cm²). The percentage compression resilience shows increasing trend with the increase in needling density both under dry and wet conditions of parallel-laid web. It also follows similar trend in case of cross-laid nonwoven under wet condition. The optimum needling density for compression resilience of cross-laid nonwoven fabric under dry condition is 250 punches/cm².     

Study on heat and moisture vapour transmission characteristics through multilayered fabric ensembles

A detailed study on the heat and moisture vapour transmission characteristics of different types of single and multi-layered fabric ensemble by using sweating guarded hot plate (SGHP) has been reported in the present paper. A comparison has been made on thermal and moisture vapour transmission properties of five different insulative fabrics, namely, knitted-raised fabric, needle punched nonwoven, through air bonded nonwoven, spunbonded-through air bonded sandwich nonwoven and warp knitted spacer fabric and three different coated fabrics, namely, plain woven rubber coated, plain woven polyester polymer coated and plain woven polytetrafluoroethylene (PTFE) coated fabric, used for thermal insulation purpose. ANOVA has been conducted to analyse the significance of type of insulative and coated fabrics used. Sandwich nonwoven fabric which has higher thickness and porosity shows higher thermal resistance followed by through air bonded fabric, raised fabric, needle punched fabric and spacer fabric. Spacer fabric shows lesser evaporative resistance due to its lesser thickness and larger aperture size, which increases the diffusion of moisture vapour. Needle punched fabric shows slightly higher evaporative resistance than spacer fabric, followed by raised fabric, through air bonded fabric and sandwich nonwoven fabric. Permeability index of different multilayered fabric ensembles are also compared.     

Functional modification of sanitary nonwoven fabric by chitosan/nanosilver colloid solution and evaluation of applicability

For their functional enhancement, sanitary nonwoven fabrics with a relatively smooth surface were treated using chitosan, a natural polymer with excellent biocompatibility, and nanosilver colloid solution, which has strong antibacterial effects even when used in small amounts. The treatment effect was examined at various mixing ratios. When the mixing ratio of the nanosilver solution was higher, antibacterial and deodorization activity was increased. For CH3/NS1 treated fabric, when the mixing ratio of chitosan and nanosilver solution was 3:1, the air permeability was most excellent, and worked as a positive in improving the pleasantness of the sanitary nonwoven fabric. In all samples, the electrostatic propensity was reduced, regardless of the mixing ratio. In terms of the moisture characteristics of chitosan/nanosilver treated nonwoven fabrics, the moisture uptake was found to be superior in the CH3/NS1 treated fabric. When the mixing ratio of the nanosilver solution was higher, moisture permeability decreased, showing a similar tendency to that of air permeability. The vertical water permeability coefficient increased in all treated fabrics. The dynamic water absorption rate was good in CH4 and CH3/NS1 treated fabrics. This means that the absorption of water in the liquid state became easier, thus improving applicability as sanitary nonwoven fabrics.     

Objective measurement of hand properties of plasma pre-treated cotton fabrics subjected to flame-retardant finishing catalyzed by zinc oxide

In the present paper, flame resistance property is imparted to cotton fabrics by N-methylol dimethylphos-phonopropionamide (Pyrovatex CP New, FR), melamine resin (Knittex CHN, CL), phosphoric acid catalyst (PA), and ZnO/nano-ZnO co-catalyst. The study shows that effectiveness of the FR-CL-PA reaction to form a crosslinked structure is enhanced by the co-catalytic reaction, resulting in enhancement of fabric’s compressional recovering ability. However, the low pH reaction weakened the fabrics, resulting in poor tensile strength and toughness, stiffer hand feel, brittle and tendered polymer layers, a less spongy fabric structure, and a roughened fabric surface with fuzzy fibrils. In addition, atmospheric pressure plasma jet (APPJ) was used to enhance materials properties by sputtering or etching effect. The roughening effect of plasma treatment enhances tensile properties of treated specimens. Nevertheless, the positive effect is negligible after post-treatment with flame-retardant agents. Moreover, the increased inter-yarn friction enhances the subjective stiffness of fabric and the rigid effect is even worse for plasma pre-treated cotton specimens subjected to flame-retardant treatment. However, plasma pre-treated specimens have a compressible structure after post-treatment with flame-retardant agents. Moreover, neutralization of flame-retardant-treated specimens helps minimize side effects of acidic finishing, irrespective of tensile and compression properties. The process also minimizes shear and bending rigid effect by removing unattached metal oxides from the fabrics.     

A study of abrasion and frictional behaviour of nonwoven interlining produced with different coating methods

Interlinings are produced recently not only natural and synthetics fibers but also fiber sheet form in nonwoven production methods. During usage, the fabric wears out and because of this problem fabric surface structure deteriorates. As a result of, investigation of fabrics surface and frictional properties has been important before usage of garments. For this reason, a patented laboratory instrument was designed which is based on horizontal working principle of accessing friction coefficient of fibrous textile surfaces. The tested materials were nonwoven interlining materials produced by spunbond methods. Abrasion resistance of paste dot-CoPES nonwoven interlining material is lower than others because of softness handle. On the contrary, friction coefficients have been obtained higher values.     

Electromagnetic shielding characteristics of woven fabrics made of hybrid yarns containing metal wire

In this study, electromagnetic shielding characteristics of woven fabrics made of hybrid yarns are investigated. For this purpose, initially the hybrid yarns containing stainless steel wire are produced with hollow spindle covering technique, and then eight different fabric samples are produced using these hybrid yarns. Electromagnetic shielding values of fabric samples are determined by a test set up based on enclosure measurement technique. Measurements are made in the frequency range of 30 MHz-9.93 GHz. Test results show that woven fabric samples investigated in this study have 25–65 dB electromagnetic shielding effectiveness for incident frequency. It was also shown that the direction, density and settlement type of conductive hybrid yarn in fabric structure are important parameters affecting electromagnetic shielding characteristics of woven fabrics.     

Porosity and nonwoven fabric vertical wicking rate

Fabric porosity is the result of fabric constructional parameters combination and used technology of nonwoven production. The effects of fabric porosity structure, as well as the content of hydrophilic viscose and hydrophobic polyester fibres in the web mixture, on the vertical wicking rate by nonwoven fabrics have been explored in this research. Fibrous webs with a different content of viscose and polyester fibres, with the web volume mass range of 0.019-0.035 g/cm³ were utilized during this study. The samples were produced using a dry-laid method of web forming and two methods of web bonding, e.g. needle punching and calendar bonding. Results show that higher volume porosity gives higher vertical wicking rate by all groups of tested samples regarding the content of used hydrophilic/hydrophobic fibres and that fluid flow is faster in samples with larger pores. The higher content of viscose fibres improve the vertical wicking rate, but better rising height can be achieved at samples made from 100 % of coarser polyester fibres. A prediction model of vertical wicking rate of viscose/ polyester nonwovens was developed on the basis of the fundamental constructional parameters of nonwoven fabrics (fibre fineness, type of raw material, and web density) and a non-deterministic modelling method, e.g. genetic algorithms, which can serve as a useful tool for fabric engineers by developing a nonwoven fabric in order to fit desired wicking rate.     

Manufacture and filtration of the PM<Subscript>2.0</Subscript> of microfiber warp-knitted mesh fabrics dealing with tourmaline

Tourmaline can enhance filtering efficiency to PM_2.0 of microfiber warp-knitted mesh fabric. In this paper, microfiber warp-knitted mesh fabrics were designed with different mesh structures and mass fraction of tourmaline solution respectively. The effect of tourmaline concentration on filtering efficiency of fabrics was investigated. After the tourmaline solution, the strength of mesh fabrics and durability of tourmaline’s conglutination to the mesh fabrics were explored at the same time. The results shown that the filtering efficiency of microfiber warp-knitted mesh fabrics dealing with tourmaline was resentful. Breaking strength of fabrics decreases with increasing mass fraction of tourmaline solution. The resistant efficiency of fabrics and tourmaline adhesive on the mesh fabrics were still stable along with the increasing mass fraction of tourmaline.     

Unprecedented Electromagnetic Shielding Effectiveness of Lightweight Nonwoven Ag/PA66 Fabrics

Novel, high-performance silver coated polyamide, Ag/PA66, nonwoven fabrics with a density of only 0.04 g/cm³ have been developed using staple fibres of 19 (3.3 dtex) and 27 (6.7 dtex) μm diameter. The obtained nonwoven fabrics with an Ag loading of 12-18 wt% exhibited excellent weight-normalised specific electromagnetic shielding effectiveness of over 1200 dB/(g/cm³) in the 0.015-3 GHz range, which is among the highest reported till date. Moreover, the applied microwave was verified to be absorbed rather than being reflected back making the fabrics highly suitable for shielding applications. It was also observed that nonwoven fabrics made from finer 3.3 dtex Ag/PA66 fibres have higher reflection and lower absorption values than their thicker (6.7 dtex) counterparts. Additionally, we have also explored the use of these nonwoven Ag/PA66 fabrics for personal thermal management via Joule heating with samples showing rapid heating response (up to 0.2 °C/sec) and long-term stability measured over 10,000 seconds. The needle-punched Ag/PA66 nonwoven fabrics, in spite of their low density of the order of 0.04 g/cm², exhibited high EMSE values of nearly 69-80 dB, leading to excellent weightnormalised specific electromagnetic shielding effectiveness of over 1200 dB/(g/cm³) in the 0.015-3 GHz range. The production of Ag/PA66 needle punched nonwoven fabrics thus offers a facile route to develop multifunctional fabrics for EMI shielding as well as personal thermal management applications.     

Developing UV-protective textiles based on electrospun zinc oxide nanocomposite fibers

This research investigates applying zinc oxide nanoparticles to polypropylene nonwoven fabrics via electrospinning for the development of UV-protective materials. Layered fabric systems with electrospun zinc oxide nanocomposite fiber webs were developed at various concentrations of zinc oxide in a range of web area densities. The effects of zinc oxide concentration and web area density on the UV-protective properties of layered fabric systems were examined. Air and moisture vapor transport properties of layered fabric systems were assessed to examine the effect of electrospun web layers on thermal comfort properties of the material. A very thin layer of electrospun zinc oxide nanocomposite fibers significantly increased the UV blocking for both UV-A and UV-B ranges, and exhibited an ultraviolet protection factor (UPF) of greater than 40, indicating excellent UV protection. UV-protective properties of layered fabric systems increased with increasing zinc oxide concentrations of the nanocomposite fiber web. Increasing the electrospun web area density of the zinc oxide nanocomposite fiber web also enhanced UV-protective properties of layered fabric systems. Air and moisture vapor transport properties of layered fabric systems decreased as the electrospun web area density increased for the range of web area densities examined.