Search Results (235)

Aramid-based polymeric fabrics are increasingly employed in lightweight protective and structural applications where high strength, flexibility, and impact resistance are required. Their response under high-velocity impact is governed by complex interactions among fiber properties, inter-yarn friction, and the mechanical behavior of the impacting body. In this work, three-dimensional finite element simulations were conducted in ANSYS Explicit Dynamics to investigate the coupled effects of the interfacial friction coefficient (μ= coefficient of friction = 0.0–0.5) and impactor material on the dynamic response of 24-layer plain-weave aramid panels. The numerical results reveal that low friction facilitates yarn mobility and localized penetration, whereas moderate friction enhances stress-wave dispersion and enables a more uniform activation of multiple fabric layers. At higher friction levels, penetration is further reduced, but localized stress concentrations may emerge due to constrained yarn movement. The constitutive properties of the impactor strongly influenced deformation modes and the efficiency of kinetic energy transfer to the composite structure. The simulated results are consistent with experimental data reported in the literature, confirming the predictive capability of the model. The study provides quantitative insight into the role of frictional interactions and impactor characteristics in optimizing the energy absorption and structural integrity of aramid-based polymeric fabrics subjected to high-velocity loading, contributing to the development of advanced lightweight protective materials. Full article

Vehicle crush boxes are one of the safety elements used in vehicles to minimize damage that may occur during an accident. The task of crush boxes is to absorb the energy which is generated during an accident. In this study, peak force, energy absorption and specific energy absorption values of cylindrical composite crush boxes, to which 0.25% and 0.50% graphene was added, were experimentally investigated with hydrothermal aging. The composite crush boxes were produced with vacuum infusion method. Glass, aramid and carbon fibers and their hybridizations were used as fibers. During hybridization, the winding order of the fibers was changed from inside to outside. The parameters for hydrothermal aging were selected as 500 h and 1000 h at 60 °C. The highest energy absorption value was obtained in the carbon fiber-reinforced sample CFRPG1H2 with 0.25% graphene-added epoxy resin matrix, aged for 1000 h. The lowest peak strength was observed in the aramid fiber-reinforced sample AFRPG2H2 with 0.50% graphene-added epoxy resin matrix, hydrothermally aged for 1000 h. It was observed that increasing the graphene addition rate reduced the negative effects on aging. It was determined that increasing the graphene ratio by 0.25% had an effect on aging. Full article

With accelerating urbanization, rivers have been severely polluted, resulting in widespread black and odorous waterways. The coagulation–sedimentation and contact oxidation bypass treatment process is characterized by low operational cost and simple operation and management. In this study, a coagulation–sedimentation–contact oxidation biofilter process was developed to treat heavily polluted malodorous blackwater. Among the tested biofilm carriers, rigid aramid fiber exhibited the fastest biofilm formation and the best pollutant removal performance. Based on a comprehensive evaluation of effluent quality and treatment capacity, the optimal operating conditions of the proposed process were identified as a PAC dosage of 50 mg/L, an air-to-water ratio of 7:1, and a hydraulic retention time (HRT) of 2 h. Under these conditions, the effluent concentrations of chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), and suspended solids (SSs) were consistently maintained below 30, 5, and 5 mg/L, respectively. Moreover, the optimized system demonstrated strong resistance to shock loading, maintaining stable operation at influent COD and SS concentrations of approximately 150 mg/L and 40 mg/L, respectively, while complying with the Class A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants. This study provides an efficient treatment strategy for malodorous blackwater remediation. Full article

Traditional firefighting protective clothing materials, such as meta- and para-aramid fibers, provide significant thermal protection but often fail to adequately manage heat stress and moisture, especially due to the incorporation of semi-permeable membranes within the three-layer garment structure known as turnout gear. Integrating hydrogels into textiles for firefighting personal protective clothing (PPC) could enhance thermoregulation and moisture management, providing firefighters with improved comfort and safety. Hydrogels are three-dimensional, hydrophilic polymer networks capable of holding substantial amounts of water. Their high water content and excellent thermal properties make them ideal for cooling applications. Therefore, this review focuses on the potential of hydrogel-infused textiles to improve firefighters’ PPC by enhancing thermal comfort and moisture management. Specifically, hydrogel structures and engineered properties for enhanced performance are presented, including smart hydrogels and hydration customization mechanisms. Hydrogel integration into firefighting PPC for moisture management and improved thermoregulation is explored, including current and future market projections and state-of-the-art clinical trial findings. Overall, the future of hydrogel-integrated textiles for firefighting PPC is bright, with numerous advancements and trends poised to enhance the safety, comfort, and performance of protective gear. Full article

This study experimentally evaluates the mechanical and microstructural performance of single- and double-layer intraply hybrid composite (IRC) laminates produced using the hand lay-up method, focusing on Glass–Aramid (GA), Aramid–Carbon (AC), and Carbon–Glass (CG) configurations. Tensile, flexural, compressive, and density tests were conducted in accordance with relevant ASTM standards to assess the influence of hybrid type and layer number under field-representative manufacturing conditions. Microstructural investigations were performed using optical microscopy and scanning electron microscopy (SEM) to identify fabrication-induced imperfections and their relationship to mechanical behavior. The results demonstrate that increasing the laminate configuration from single to double layer significantly enhances mechanical performance across all hybrid types. Double-layer AC laminates exhibited the highest tensile strength (330.4 MPa) and Young’s modulus (11.93 GPa), corresponding to improvements of approximately 85% and 59%, respectively, compared to single-layer counterparts. In flexural loading, the highest strength was observed in double-layer CG laminates (97.14 MPa), while compressive strength was maximized in double-layer AC laminates (34.01 MPa), indicating improved stability and resistance to compression-driven failure. Statistical analysis confirmed that layer number is the dominant parameter governing mechanical response, exceeding the influence of hybrid configuration alone. Microstructural observations revealed fiber misorientation, incomplete resin impregnation, and localized voids inherent to manual fabrication. However, these imperfections were consistently distributed across all specimens and did not obscure comparative mechanical trends. Coefficients of variation generally remained below 10%, indicating acceptable repeatability despite non-ideal manufacturing conditions. Full article

Aramid fiber is increasingly regarded as an important skeleton material in the conveyor belt industry. However, its application is limited by problems such as short splice service life and low strength retention. This study investigates the finger splice of an aramid rubber conveyor belt. A finite element model was established to analyze the effects of different rubber hardness values (60, 65, 70, 75), environmental temperatures (−20 to 40 °C), and finger widths (10 mm, 12 mm, 15 mm, 20 mm, 30 mm) on splice mechanical performance. The results show that the maximum stress is concentrated at the end surfaces of the reinforcement layer and the fingertips of the skeleton material. The splice strength increases with higher rubber hardness but decreases with rising environmental temperature. To improve splice strength, the rubber hardness and environmental temperature should be controlled within 60–70 and 0–20 °C, respectively. Although reducing finger width increases splice strength, excessively small widths lead to stress concentration and manufacturing difficulties. Therefore, finger width selection should consider actual working conditions. The experimental results are compared with simulation results, and the trend consistency verifies the correctness of the simulation. This study provides a theoretical basis for parameter selection and structural design of the splice under various working conditions. Full article

This study examines the use of electronic waste (e-waste) as an alternative material in concrete for sustainability and natural resource conservation. Various e-wastes, such as Polyvinyl Chloride (PVC), Glass-Reinforced Plastic (GRP), Glass Fiber-Reinforced Polymer (GFRP), cross-linked polyethylene (XLPE), polyethylene (PE), electronic cable waste (ECW), Waste Electrical Cable Rubber (WECR), copper fiber (Cu Fib.), aluminum Fibers (Al fib.), steel fibers, basalt fibers, glass fibers, aramid−carbon fibers, Kevlar fibers, jute fibers, and optical fibers, were tested for influence on compressive, flexural, tensile strength, modulus of elasticity, and water absorption. Outcomes show that fine particle waste at low levels (0.2–1.5%) can improve mechanical performance, while higher levels of replacement or coarse particles generally reduce performance. Mechanical and physical properties are highly sensitive to material type, particle size, and dose. Life cycle assessment (LCA) and predictive modeling are recommended as validation for sustainability benefits. Full article

In response to mounting resource and environmental pressures in the textile industry, this study investigates the feasibility of fiber-to-fiber closed-loop recycling for used firefighting protective clothing—a waste stream characterized by material homogeneity and large-scale disposal. Employing a mixed-methods approach combining stakeholder questionnaires, field investigations (n = 3650), and performance testing of retired aramid fabrics, this research systematically evaluates the technical, market, and systemic potential for circular regeneration. Results demonstrate strong multi-stakeholder support (over 89%) and significant consumer willingness to purchase recycled products (81.01–84% across categories), while material tests confirm the retained flame resistance and mechanical properties of the fabrics, enabling high-value applications. By constructing an integrated framework spanning technical, policy, market, and cultural dimensions, and proposing strategies of “targeted recycling” and “value reconstruction,” this work confirms the commercial viability and environmental benefit of recycling firefighting gear. It further offers a transferable model for advancing the circularity of other safety and protective textiles, with key innovations lying in its comprehensive full-chain assessment and the concurrent validation of stakeholder dynamics and material performance. Full article

High-viscosity aramid copolymer solutions are widely used in fiber manufacturing and advanced composite applications, but their elevated viscosity poses significant challenges for mixing and agitation processes. This study employs computational fluid dynamics (CFD) simulations to enhance the mixing performance of such systems. Flow behavior around the impeller was analyzed within a cylindrical stirred tank while varying the number of baffles (0, 2, 4, and 6) and comparing two different impeller designs (A and B). Simulation results showed that installing a sufficient number of baffles—particularly four—effectively suppressed swirling flows commonly observed in high-viscosity fluids, thereby significantly improving mixing efficiency. Additionally, impeller geometry played a critical role in performance: the axial-flow impeller promoted faster homogenization and broader circulation compared with the radial-flow design. Through this CFD-based analysis, this study elucidates the key mechanisms governing mixing in high-viscosity fluids and provides practical design and operational guidelines for industrial stirred tank systems. These findings complement existing empirical guidelines focused on low-viscosity fluids and contribute to improving the efficiency and reliability of high-viscosity polymer processing. Full article

Aramid Fiber Reinforced Plastic (AFRP) and aluminum alloy Al7075-T6 are widely used in the aerospace industry because they offer a high strength-to-weight ratio and reliable structural performance. However, drilling through stacked AFRP and Al7075-T6 materials in a single operation presents considerable challenges due to the differences in their mechanical and thermal properties. In this study, three types of customized twist drill bits were designed and fabricated to evaluate their effectiveness in single-shot drilling of these stacked materials. The drill geometries included the W-point design, the tapered web design, and the burnishing design. Each drill bit was tested using its own optimized drilling parameters to produce a total of one hundred holes. The aim was to determine which drill geometry provided the best overall performance in terms of tool wear and hole quality. After the drilling experiments, the tool tips were examined using a Scanning Electron Microscope (SEM) to observe wear characteristics and analyze elemental composition. The analysis revealed that aluminum adhered to the cutting lips of all drill bits. The percentage of adhesion layer, known as percentage of adhesion layer (PAL), was calculated to assess the severity of material adhesion. In addition, the morphology of the produced chips and dust was analyzed to support the PAL results. The findings showed that the drill bit with the lowest PAL value demonstrated superior wear resistance, a longer tool life, and the ability to produce holes of higher quality when drilling AFRP and Al7075-T6 stacked materials. Full article

Hierarchical aramid/zirconia hybrid fibers were introduced into the interlayers of basalt fiber–reinforced polymer (BFRP) composites to optimize their interlaminar properties. The reinforcing effect of micro/nano aramid short fiber (MNASF) and zirconia fiber (ZF) on BFRP composites at different mass ratios was investigated through three-point bending (3PB) tests and compression tests. The results demonstrated that the BFRP composites incorporating 2 wt.% MNASF and 2 wt.% ZF exhibited the most significant property enhancement. The 3PB tests revealed increases in flexural strength and modulus of 119.2% and 62.6%, respectively, compared to the unreinforced BFRP composites. Compression tests showed that this specific formulation enhanced the compressive strength and modulus by 257.7% and 121.6%, respectively. Scanning electron microscopy and optical microscopy observations indicated that the incorporation of MNASF and ZF effectively reduced the volume fraction of resin-rich regions in the interlaminar regions, and the dominant failure mode transitioned from delamination to shear failure. Overall, the introduction of MNASF and ZF effectively combined the reinforcing effects of the two fibers, improving the mechanical properties of BFRP composites. Full article

The technology of 3D printing has become one of the most effective methods of creating various parts, such as those used for fast prototyping. The most important aspect of 3D printing is the selection and application of the appropriate material, also known as filament. The current review concerns mainly the description of the mechanical and physical properties of the different filaments and the possibilities of improving those properties. The review begins with a short description of the development of 3D printing technology. Next, the basic characteristics of thermoplastics used in the fused filament fabrication (FFF) are discussed, namely polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and polyethylene terephthalate glycol (PETG). According to modern concepts, the printed parts can be reinforced with the use of different kinds of fibers, namely synthetic fibers (carbon, glass, aramid) or natural fibers (wood, flax, hemp, jute). Thus, the impact of such a reinforcement on the performance of FFF composites is also presented. The current review, unlike other works, primarily addresses the problem of the aging of parts made from the thermoplastics above. Environmental conditions, including UV radiation, can drastically reduce the physical and mechanical properties of printed elements. Moreover, the current review contains a detailed discussion about the influence of the different fibers on the final mechanical properties of the printed elements. Generally, the synthetic fibers improve the mechanical performance, with documented increases in tensile modulus reaching, for instance, 700% for carbon-fiber-reinforced ABS or over 15-fold for continuous aramid composites, enabling their use in functional, load-bearing components. In contrast, the natural ones could even decrease the stiffness and strength (e.g., wood–plastic composites), or, as in the case of flax, significantly increase stiffness (by 88–121%) while offering a sustainable, lightweight alternative for non-structural applications. Full article

The aramid honeycomb composite material plays an important role in industry. Defects of this material seriously influence its performance. However, conventional detecting tools such as X-ray or computer tomography (CT) imaging, ultrasonic testing, and visual inspection are not able to meet the requirements of fast, safe, and high resolution at the same time. In this study, we numerically use rapid terahertz time−domain spectroscopy (THz-TDS) to identify defects in the aramid paper composite structure effectively. Simulation results demonstrate that THz-TDS technology enables the non-destructive reflection imaging of layered defects in glass fiber covering and glue layers as supporting components within the composite structure, with a spatial resolution of 0.5 mm and a depth range exceeding 10 mm. During the study, the finite difference time domain (FDTD) simulation with a real pulse waveform is achieved, and the defect position can be recognized by the anomaly in the reflection profile when compared with the waveform reflected by non-defect samples. At the same time, it is found that the defect identification ability is obviously affected by the incident position. The numerical research illustrates that the detectable defect is as thick as 0.1 mm and has a diameter of 1 mm. The results will offer valuable guides to the real application of THz-TDS systems in the detection of a similar structure. Full article

The deployable reflector antenna mounted on the SAR satellite is an antenna with a folding structure and is one of the main components of the satellite body. Due to the limited space inside the launch vehicle fairing, the mounting efficiency was improved by applying a structural feature that allows the antenna to be stowed compactly. In addition, weight reduction was required to lower launch costs and improve the satellite revisiting cycle; therefore, the main reflector of the deployable reflector antenna was designed and manufactured using carbon fiber reinforced polymer and aramid honeycomb core. Since the main reflector made of carbon fiber-reinforced polymer and aramid honeycomb core is not an isotropic material, differences between theoretical and actual thermal properties were expected. Therefore, in this study, a thermal balance test was performed on the thermal structure model of the deployable reflector antenna, and the thermal analysis model simulated by the ground test was corrected using the verified temperature conditions as a reference. The thermal properties of the composite material and the thermal conductivity coefficient between the main reflector and the main components connected to it were the targets of correction. In addition, a numerical optimization technique was applied to reduce computational costs, and the thermal analysis assumed the orbital environment model of the deployable reflector antenna was optimized using the corrected thermal properties. Full article

This research highlights the issue that large amount of sweat generated by metabolism cannot be discharged from the internal environment of traditional fire suits when firefighters are intensively operating in high-temperature environments. This is highly prone to bacterial growth, which brings much harm to their health. Therefore, this study aims to present a new fire-retardant fabric with both antibacterial and high hygroscopic properties. Blended fibers were used including aramid 1313 fibers with excellent flame retardancy and flame-retardant viscose fibers. By uniformly embedding antibacterial nanofibers into the microfiber aggregates and controlling the adhesion behavior at the cross-scale interfaces of micro–nano fibers, the fire-retardant yarns were endowed with both antibacterial and moisture-transporting properties. The bacterial inhibition rate was calculated by comparing colonies cultured on EF fabric versus NF fabric. Additionally, the antibacterial and moisture-wicking properties of the fabrics were verified through tests such as placing the fabrics vertically in liquid to measure the height of absorbed moisture. This prepared functionally integrated fabric has excellent antibacterial properties even after 50 washing cycles. Its antibacterial rate against Escherichia coli and Staphylococcus aureus kept a preferred result of 99%. Its moisture-transporting performance has also been significantly improved. Based on the above, this study has not only successfully developed a flame-retardant fabric with high antibacterial and moisture-wicking properties, but more importantly, the method demonstrates a degree of universal applicability. Full article