Aramid Fabrics Research Articles

Flexural behavior of high-performance and non-high-performance textile reinforced concrete composites

The flexural behaviour of textile reinforced concrete (TRC) samples reinforced with two types of textile, (1) polypropylene (PP) roving with a low elastic modulus and (2) aramid roving with a high elastic modulus, is studied and compared. The TRC samples are reinforced using up to eight layers of plain weaved fabrics with the mesh size of 5 mm and 10 mm. Flexural behaviour and capacity of composite specimens are investigated using a four-point bending test. The microstructure of cement matrix and fibres is also studied using SEM images. It was found that the flexural strength of TRC samples strengthened with PP and Aramid textiles increased by increasing the number of fabric layers. Reducing the fabric mesh size increased the bending strength of Aramid TRC samples because of the chemical bond between Aramid fibres and concrete. On the contrary, PP fabrics with larger mesh sizes showed higher bending moment strength as the connection between PP fabrics and concrete is mechanical. A large number of PP fabrics in TRC specimens caused delamination; therefore, roving reinforced concrete (RRC) instead of TRC was used to increase the reinforcement ratio in specimens. The test results of TRC and RRC samples showed that the flexural behaviour of samples reinforced with PP longitudinal roving (reinforcement ratio of 1.60% PP roving) was similar or even better than samples reinforced with high-modulus Aramid fabrics (reinforcement ratio of 0.92% Aramid fabric) in terms of strength and stiffness.

Tailoring the Rheology of Shear Thickening Fluids by Regulating the Particle Size of Dispersed Phase for Enhancing the Impact Resistance of Aramid Fabrics

Tailoring the Rheology of Shear Thickening Fluids by Regulating the Particle Size of Dispersed Phase for Enhancing the Impact Resistance of Aramid Fabrics

Green synthesis of nanosilver using Fomes fomentarius mushroom extract over aramid fabrics with improved coloration effects

Silver nanoparticles (AgNPs) were greenly synthesized over aramid fabrics from wild mushroom ( Fomes fomentarius) to develop colorful products. The localized surface plasmon resonance characteristics of AgNPs provided versatile coloration effects on fabrics, with improved color strength ( K/ S) and other colorimetric values ( L*, a*, and b*). The stability of the colored materials was also investigated in terms of color fastness to wash and rubbing (both wet and dry states). The characteristics of deposited AgNPs over aramid materials were characterized by X-ray fluorescence spectroscopy testing of solid fabric samples. Morphological properties of the aramid substrates were investigated using SEM (scanning electron microscopy) testing to check the surfaces both for nanosilver-treated and untreated materials. Moreover, the developed nanoparticles were also confirmed further using SEM-deployed energy-dispersive X-ray spectroscopy and elemental mapping analysis. The chemical bonding between the aramid fiber and deposited AgNPs was tested using Fourier infrared spectroscopy analysis. The thermal stability of the aramid fabrics was examined in order to investigate their behavior when exposed to heat in terms of thermogravimetric analysis and derivative thermogravimetry analysis. The K/ S values and darkness values were increasing with the increased loading of the nanosilver precursor. Moreover, statistical analysis was also conducted in terms of the coefficient of variation ( R2) to understand the significance of the connection between the nanosilver loading and coloration characteristics, and found a significant relationship. Overall, a novel, sustainable, and facile biosynthesis route of AgNPs is reported in this current research.

Silver Nanowires and Silanes in Hybrid Functionalization of Aramid Fabrics.

New functionalization methods of meta- and para-aramid fabrics with silver nanowires (AgNWs) and two silanes (3-aminopropyltriethoxysilane (APTES)) and diethoxydimethylsilane (DEDMS) were developed: a one-step method (mixture) with AgNWs dispersed in the silane mixture and a two-step method (layer-by-layer) in which the silanes mixture was applied to the previously deposited AgNWs layer. The fabrics were pre-treated in a low-pressure air radio frequency (RF) plasma and subsequently coated with polydopamine. The modified fabrics acquired hydrophobic properties (contact angle ΘW of 112–125°). The surface free energy for both modified fabrics was approximately 29 mJ/m2, while for reference, meta- and para-aramid fabrics have a free energy of 53 mJ/m2 and 40 mJ/m2, respectively. The electrical surface resistance (Rs) was on the order of 102 Ω and 104 Ω for the two-step and one-step method, respectively. The electrical volume resistance (Rv) for both modified fabrics was on the order of 102 Ω. After UV irradiation, the Rs did not change for the two-step method, and for the one-step method, it increased to the order of 1010 Ω. The specific strength values were higher by 71% and 63% for the meta-aramid fabric and by 102% and 110% for the para-aramid fabric for the two-step and one-step method, respectively, compared to the unmodified fabrics after UV radiation.

Strong interfacial modified aramid fabric reinforced degradable thermosetting composites: reinforcing and tribological effects

In this work, dense molybdenum disulfide (MoS2) nanosheets were grown onto polydopamine (PDA) functionalized aramid fabric (AF) surface via a simple hydrothermal method to improve the wettability between AF surface and polyhexahydrotriazine (PHT) resin, thus resulting in stronger AF/resin interfacial bonding. The PDA-assisted surface modification on AF generated a high active interface allowing the nucleation and subsequent growth of MoS2. Moreover, this nanosheet-coated reinforcement fiber enabled the viscous liquid of resin precursor to spread over and form intimate contact with its surface, which eventually promoted the formation of strong interfacial bonding between AF-MoS2 and cured resin matrix. In addition, the enhanced interfacial bonding between the reinforcement and matrix generated stable mechanical interlock within the resulting AF-MoS2/PHT composites, and thus, contributed better thermal stability, higher tensile strength, and tribological properties. Compared with AF/PHT composites, the tensile strength and elongation at break of the AF-MoS2/PHT composites increased by 32.5% and 50%, and the average friction coefficient and wear rate of AF-MoS2/PHT composites decreased by 43.9% and 86.3%, respectively. Furthermore, the composites realized the non-destructive recovery of expensive AF at 25 °C. Overall, our study demonstrates a dependable strategy to construct the recyclable AF-MoS2/PHT composites, which exhibit valuable applications in tribology.

Changes in Mechanical Characteristics of HPC Samples Modified with WC and WO<sub>3</sub> Nanopowder Agglomerates

The paper presents the results of tests of HPC (high performance composites) samples consisting of aramid and glass fabrics modified by agglomerates of WC and WO3 nanopowders. According to the test results, introduction of WC and WO3 powders into the composite plate structure makes it more rigid and elastic, increasing its ability to dissipate energy.

Internal friction properties of carboxylated cellulose nanofibers (CNF-C) modified aramid woven fabrics

The internal friction properties of the aramid woven fabrics modified by carboxylated cellulose nanofibers (CNF-C) were studied, in order to better investigate the effect of CNF-C on the internal friction properties of the aramid woven fabrics, the yarn pull-out force of the modified aramid fabrics were tested by single yarn pull-out test. The chemical structure and surface morphology of the aramid fibers were characterized by Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the strong hydrogen bond between CNF-C and aramid fiber and the dipole–dipole interaction between the polar groups of the fiber (such as –NH, –C = O) and hydroxyl groups are the bond mechanism. Compared with the untreated fabrics, the yarn pull-out force and fiber surface roughness of the CNF-C modified aramid fabrics are significantly improved. When the impregnation time is 0.5 h and the CNF-C concentration is 1 wt%, the yarn pull-out force reaches the maximum of 13.3 N, which is increased by 133.3% compared with the untreated aramid fabrics. The internal friction properties of the aramid woven fabrics are obviously increased by modification.

Electrothermal Performance of Heaters Based on Laser-Induced Graphene on Aramid Fabric.

Nanostructured heaters based on laser-induced graphene (LIG) are promising for heat generation and temperature control in a variety of applications due to their high efficiency as well as a fast, facile, and highly scalable fabrication process. While recent studies have shown that LIG can be written on a wide range of precursors, the reports on LIG-based heaters are mainly limited to polyimide film substrates. Here, we develop and characterize nanostructured heaters by direct writing of laser-induced graphene on nonuniform and structurally porous aramid woven fabric. The synthesis and writing of graphene on aramid fabric is conducted using a 10.6 μm CO2 laser. The quality of laser-induced graphene and electrical properties of the heater fabric is tuned by controlling the lasing process parameters. Produced heaters exhibit good electrothermal efficiency with steady-state temperatures up to 170 °C when subjected to an input power density of 1.5 W cm–2. In addition, the permeable texture of LIG–aramid fabric heaters allows for easy impregnation with thermosetting resins. We demonstrate the encapsulation of fabric heaters with two different types of thermosetting resins to develop both flexible and stiff composites. A flexible heater is produced by the impregnation of LIG–aramid fabric by silicone rubber. While the flexible composite heater exhibits inferior electrothermal performance compared to neat LIG–aramid fabric, it shows consistent electrothermal performance under various electrical and mechanical loading conditions. A multifunctional fiber-reinforced composite panel with integrated de-icing functionality is also manufactured using one ply of LIG–aramid fabric heater as part of the composite layup. The results of de-icing experiments show excellent de-icing capability, where a 5 mm thick piece of ice is completely melted away within 2 min using an input power of 12.8 W.

Experimental investigation of the impact resistance on KEVLARXP S308® fabric impacted with truncated ogive projectile subjected to pre-tension

Aramid fabrics made of polymeric chains have wide use in ballistic applications due to their low density, high strength, and their excellent resistive behavior to high strain rate loading like terminal ballistic impact. The response of the aramid yarns depends on yarn architecture, the shape of impacting projectile, and the boundary conditions fabric is subjected to. This work is focused on studying the ballistic response of KEVLARXP S308® manufactured by DuPont. The fabric has a unique +45°/−45° layer sequence with interlaced stitches and would be impacted by a truncated ogive projectile at different levels of fabric pre-tension. A new experimental setup is designed to induce circumferential pre-tension to the fabric and record the fabric's contact force response on impact. The fabric's terminal ballistic parameters like ballistic limit, peak force, time duration, and energy absorption were examined. The ballistic parameters were studied for three different levels of pre-tension, 100 N, 200 N, and 300 N. For each of the pre-tension, the SEM micrograph images were studied for range V30 to V70, and various modes of failure like fibrillation, yarn pull-out, yarn bowing, yarn shearing were analyzed at and near the ballistic limit for both the layers in the fabric. The study findings indicate that the presence of stitches in the fabric restricts the mobility of the yarns in the transverse direction up to a certain extent, and leads to a decrease in the ballistic limit velocity for higher pre-tension value. The analysis of change in peaks of the force-deflection curves in increasing values of impact energy showed the increased strain energy transfer from +45° layer to +45° layer.

Polypyrrole coating on aramid fabrics for improved stab resistance and multifunction

As an epoch of intelligent clothing is coming, soft body armor is required to possess not only improved mechanical performance but more functions, such as electronic conductivity, anti-ultraviolet capability, electrical heating property, etc. In this work, polypyrrole (PPy) is coated on Twaron fabrics to enhancing their stabbing resistance and simultaneously endowing them with multifunction. The resultant PPy-coated Twaron fabric exhibits better tensile strength. The strength of the PPy-coated fiber is increased by 12.03% and the maximum friction between the yarns in the PPy-coated fabric increases by 8.96 times. The quasi-static stab resistance of the PPy-coated fabric is also significantly improved in comparison with that of the neat counterpart. Furthermore, PPy-coated fabric exhibits anti-ultraviolet capability, high electrical conductivity, and stable electrical heating properties. The saturation temperature from the electrical heating is tunable by adjusting the applied voltage. These functions ensure that the treated fabrics can be applied in more areas and facilitate relieving the adverse effects from the external environment (rainstorm, blizzard, insolation, etc.) for the soft body armor. This study offers the potential of developing the novel generation of smart soft body armor with both excellent protective performance and intelligent wearable properties.

Fabrication and preliminary assessment of aramid reinforced polymer composite material

A knowledge of the material constituents and fabrication process is generally required for easing the composite material properties study and characterization. This paper presents the methodology of aramid reinforced polymer composite material preliminary assessment and fabrication. The demonstration is carried out through the development of mechanical properties characterization specimen. The composite material specimen is fabricated by utilizing the open mould with hand lay-up method, where three types of laminates include of unidirectional, orthotropic, quasi-isotropic cross plies are demonstrated. A template is applied for preparing specific fibre orientation 45°angle. Plies are lay accordingly with guided by a square guide for minimizing the off-orientation angle defect. Preliminary assessment is included of verification of unidirectional aramid fabric quality, cured specimen physical defect, internal defect through micrography analysis and material volume fraction prediction. Average specimen fibre volume fraction of 0.64 is predicted by determined the fibre filament geometry detail through micrography analysis. There are several fabrication defects had been identified. The defect identification findings shall be referred for further improvement of material preparation and fabrication method.

Determination of changes in the mechanical properties of polymer composites with the addition of agglomerates of WC nanopowder

Recently, there has been a growing interest in the development of new composite materials with improved characteristics. The article presents the results of tests of composite specimens based on aramid fabrics modified with WC nanopowder agglomerates obtained from carbide manufacturing waste. The following mechanical characteristics were investigated: transverse bending resistance, fracture resistance and energy absorption during contact with a physical body at high speed. According to the results, the transverse bending resistance increased by 35% at a WC concentration of 5%. When 3% WC powder was added to the matrix composition, the total crack length after impact was almost halved. The largest increase in energy absorption of the samples was about 30% at 1% additive concentration. The significant increase in the investigated parameters can be explained by the complex morphology of the embedded particles. In further investigations it is planned to study in detail the mechanism of distribution of nanodispersed WC powder additive in the volume of the modified material.

Numerical and Experimental Study of Hybrid Composite Body Armor

Kevlar is widely used in ballistic applications to protect against hand pistols, due to its high strength, lightweight, and high impact resistance. Compared to other fabrics, Kevlar is considered a typical material due to its strength properties for bullet-proof vests. This project aims to develop a hybrid composite and investigate its behavior under ballistic impact both experimentally and theoretically. Ceramic/woven fabric reinforced epoxy/polycarbonate multilayered armors were developed. The initial layer of defense against the bullet is silicon carbide (SiC). The intermediate composite is made up of aramid fabric (Kevlar) reinforced epoxy (KEV/EPX). The rear layer was made of polycarbonate (PC). A 9 mm FMJ bullet was fired in 310 m/s, towards samples of 900 cm2. To simulate the ballistic test, Ansys Workbench Explicit Dynamics and Ansys AUTODYN 3D were used. An integrated methodological approach of experimentation and simulation was followed to assess the behavior of samples. Obtained results showed that SiC+ KEV/EPX+ polycarbonate was able to stop the 9mm FMJ bullet and indicated that armor layers perforated without penetration. Back Face Signature BFS was also measured, which is within the allowed limit. The ceramic layer absorbs the largest percentage of the overall energy absorbed, compared to fiber-reinforced epoxy and polycarbonate, which reach 77.8% of the entire energy.

Effect of cationic protein auxiliary on the reactive dyeing properties and structure of aramid fabric

Aramid fabric was plasticized and modified with combination of carrier CWP-N and cationic gelatin protein auxiliary. The dyeing property of the treated aramid fabric dyed with reactive dyes was evaluated. And the modification mechanism of aramid fabric and its reactive dyeing mechanism were analyzed. Then, the structures of the treated aramid fabric were characterized with Fourier transform infrared (FTIR), scanning electron micrograph (SEM), surface friction properties and X-ray diffraction analysis, respectively. In addition, the glass transition temperature and the thermal properties of the treated aramid fabric were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), respectively. The results showed that the dyeing properties of the treated aramid fabric to reactive dyes were improved highly. Compared with the untreated aramid fabric, the dye uptake of the treated aramid fabric increased by more than 2.7 times, the color depth (K/S value) after soaping increased by more than 8 times, and the dye total fixation rate increased by more than 3.2 times. The chemical structure and surface morphology of the treated aramid fabric were changed significantly. And the glass transition temperature of the treated aramid fabric was reduced. The main reason for the significant improvement of reactive dyeing properties of the treated aramid fabric was the change of its structure. However, the crystallinity of the treated aramid fabric was almost unchanged. And the thermal stability of the treated aramid fabric was reduced.

Ballistic performance of B4C/STF/Twaron composite fabric

This work proposes a new type of bullet-proof composite fabric, which is made of B4C modified shear thickening fluid (STF) and Twaron aramid fabric. We conducted yarn pull-out test, ballistic impact test and finite element analysis (FEA) to investigate the ballistic performance of this new type of composite fabric. Based on the yarn pull-out test, it is found that the inter-yarn friction is greatly increased after the aramid fabric is impregnated with the B4C modified STF. The ballistic test shows that the ballistic limit velocity of single-layer neat Twaron fabric can be improved from 114 m/s to 160 m/s by using pure STF while 179 m/s by using the B4C modified STF where 10% B4C of particle size W3.5 was added into the STF. For multiple layers of fabrics, the ballistic performance of 3-layer B4C/STF/Twaron composite fabric is better than 3-layer neat Twaron whereas worse than 4-layer neat Twaron (which is of similar areal density to 3-layer composite). In order to study the ballistic properties of the composite fabric composed of fabric impregnated with B4C modified STF and neat fabric, the ballistic performance of 6-layer fabric was studied. By optimizing the combination of fabrics, we found putting 1 layer of B4C/STF/Twaron composite fabric in front of 5 layers of neat Twaron fabrics can maximize the overall ballistic resistance of the structure with the similar areal density. The simulation results agree well with the experimental results, which shows the path stress wave propagates and further emphasizes that the friction coefficient between yarns has a significant impact on the anti-impact property of fabric.

Hydrogel with high toughness and strength for fabricating high performance stab-resistant aramid composite fabric

In order to prepare a new high-performance and flexibility stab-resistant composite material, one type of high-toughness and high-strength hydrogel is combined with aramid fabric. In this paper, the nanocomposite (NC) hydrogels are prepared using Pluronic F127 Diacrylate (PF127DA) as the crosslinking agent, acrylamide as the monomer and nano-silica as nano additive. The influence of the addition amount of nano-silica on the toughness and strength of nano-composite hydrogels is discussed. The strength and toughness of the NC hydrogels with nano silica are higher than that of the acrylamide hydrogel without nano particles. The NC hydrogel with the best strength is made as a composite with aramid fabric and the effect of nanocomposite hydrogel on the stab resistance of the stab-resistant composite material is studied. The research shows that the stab resistance performance of the composite material prepared by aramid fabric and nanocomposite hydrogel is effectively improved in comparison with aramid fabric, and the yarn pulling force is also improved. The composite material with high stab resistance can be used as the stab-resistant layer of armor, cut-resistant gloves and stab-resistant base material of shoes. This work provided a possibility for preparing a kind of lightweight composite material with high stab resistance.

Investigation of the stab resistance mechanism and performance of uncoated and SiO2 coated high-performance aramid fabrics

Surface coatings on the fabrics can enhance protective properties of flexible body armors. It is known that the application of coating increases inter yarn friction, however, detailed mechanism of knife-yarn interaction in coated and uncoated fabrics is not fully understood yet. This study investigates in detail the knife-yarn interaction at individual yarn level and role of improved inter yarn friction in enhanced stab resistance of woven aramid fabrics deposited with SiO2 coating. The coated fabric exhibited an increase of 115% in the knife penetration resistance compared with uncoated fabric due to increase in inter yarn friction. The coefficient of friction increased 29% after coating. The video graphicanalysis performed during quasi static stab resistance revealed important insights into the knife to yarn interactions. The filaments within the yarn in the uncoated fabric interact individually with the knife, undergo sequential cutting of filaments and offer less resistance to knife penetration. On the other hand, filaments within the yarn in the coated fabric were found to interact collectively, as cohesive assembly of fibers, undergo simultaneous cutting offering greater resistance to the penetrating knife. The results of yarn pull out, yarn sliding, single yarn cut resistance and single yarn strength tests confirmed that improvement in the stab resistance was attributed mainly to the increased inter yarn friction after coating the fabric while intrinsic properties of the yarn were not altered. The findings of this study will be helpful in the development of protective clothing with improved stab resistance.

Impact Response of Aramid Fabric-Reinforced Polybenzoxazine/Urethane Composites Containing Multiwalled Carbon Nanotubes Used as Support Panel in Hard Armor.

The aim of this research project is to analyze support panels that are based on aramid fabrics which are reinforced with polybenzoxazine/urethane (poly(BA-a/PU)) composites and contain multiwalled carbon nanotubes (MWCNTs). Through the measurement of mechanical properties and a series of ballistic-impact tests that used 7.62 × 51 mm2 projectiles (National Institute of Justice (NIJ), level III), the incorporated MWCNTs were found to enhance the energy-absorption (EAbs) property of the composites, improve ballistic performance, and reduce damage. The perforation process and the ballistic limit (V50) of the composite were also studied via numerical simulation, and the calculated damage patterns were correlated with the experimental results. The result indicated hard armor based on polybenzoxazine nanocomposites could completely protect the perforation of a 7.62 × 51 mm2 projectile at impact velocity range of 847 ± 9.1 m/s. The results revealed the potential for using the poly(BA-a/PU) nanocomposites as energy-absorption panels for hard armor.

Energy Absorption and Limit Velocity of Epoxy Composites Incorporated with Fique Fabric as Ballistic Armor-A Brief Report.

Polymer composites reinforced with natural fabric have recently been investigated as possible ballistic armor for personal protection against different levels of ammunition. In particular, fabric made of fique fibers, which is extracted from the leaves of the Furcraea andina, was applied as reinforcement for polymer composites used in a multilayered armor system (MAS). The superior performance of the fique fabric composites as a second MAS layer motivated this brief report on the determination of the absorbed energy and capability to limit velocity in the stand-alone ballistic tests. The single plates of epoxy composites, which were reinforced with up to 50 vol% of fique fabric, were ballistic tested as targets against 7.62 mm high-speed, ~840 m/s, impact ammunition for the first time. The results were statistically analyzed by the Weibull method and ANOVA. The absorbed energies of the 200–219 J and limit velocities of 202–211 m/s were found statistically similar to the epoxy composites reinforced with the fique fabric from 15 to 50 vol%. Predominantly, these findings are better than those reported for the plain epoxy and aramid fabric (KevlarTM) used as stand-alone plates with the same thickness. Macrocracks in the 15 and 30 vol% fique fabric composites compromise their application as armor plates. The delamination rupture mechanism was revealed by scanning electron microscopy. By contrast, the integrity was maintained in the 40 and 50 vol% composites, ensuring superior ballistic protection compared to the use of KevlarTM.

Increasing the rigidity of an elastic working tool for processing thin sheet metal by creating composite material based on polyurethane elastomers and synthetic aramid fabrics

sThe paper presents the results of both experimental and theoretical studies on the creation of a new composite working tool for pressure treatment of thin sheet metals. The composite working tool is made on the basis of SKU-7L polyurethane with reinforcement with one layer of kevlar-type aramid fabric.