Search Results (33)

Polybenzimidazole (PBI), a high-performance polymer known for its exceptional thermal stability and chemical resistance, was processed by solution electrospinning to manufacture fibrous non-woven membranes. The process was repeated under different conditions by adjusting four main settings: the polymer solution concentration, the flow rate, the voltage applied between the needle and the collector, and the separating distance. To clarify the interplay between process parameters and material properties, a Design of Experiment (DOE) approach was used to systematically analyze the effects of said parameters on microstructural properties, including fiber diameter, porosity, and air permeability, pointing out that the increase in viscosity improves fiber uniformity, while optimizing the applied voltage and the needle–collector distance enhances jet stability and solvent evaporation, crucial for defect-free fibrous microstructures. Post-processing via calendering further refined the membrane texture and properties, for example by reducing porosity and air permeability without significantly altering the fibrous morphology, particularly at low lamination ratios. Thermal and mechanical evaluations highlighted that the obtained electrospun PBI membranes exhibited enhanced flexibility, but lower tensile strength compared to cast films due to the underlying open pore microstructure. This integrated approach—combining experimental characterization, DOE-guided optimization, and post-processing via calendering—provides a systematic framework for tailoring PBI membranes for specific applications, such as filtration, fuel cells, and molecular sieving. The findings highlight the potential of PBI-based electrospun membranes as versatile materials, offering high thermal stability, chemical resistance, and tunable properties, thereby establishing a foundation for further innovation in advanced polymeric membrane design and applications for energy and sustainability. Full article

The reuse of recycled carbon fibers (rCF) is a response to growing environmental concerns associated with the composites industry. Recycling and reusing carbon fibers represents a more sustainable alternative by reducing waste at the end of the life cycle of composite materials and decreasing dependency on virgin raw materials. This study investigates the influence of process parameters on two different non-woven mats made by carding rCF and blending with thermoplastic filaments: Carbiso TM-PA6/60 and TM-MAPP/60. Two processing methods were examined—one-shot process (M1) and lamination (M2)—to fabricate multilayer coupons. The results indicate that the two-layer panels produced using M2 exhibited a lower porosity (9.9% for PA6/60 and 4.1 for MAPP/60) and superior mechanical performance. However, the differences in performance between the two methods diminished as the number of layers increased. Concerning matrix–fiber compatibility, MAPP/60 showed the best results due to the fiber’s roughness, matrix particles on the fibers, and the incorporation of maleic anhydride in polypropylene (PP), significantly enhancing adhesion. Full article

To address the increasingly complex demands of noise control, this study investigated the integration of a micro-perforated nanofiber membrane (MPNM) with nonwoven fiber felt (NFF), exploiting their synergistic effects to achieve efficient low-frequency broadband sound absorption. Through theoretical analysis, numerical simulations, and experimental validation, the relationship between the sound absorption performance of the composite structure and factors such as the lamination sequence, bonding area, perforation parameters, thickness of the MPNM, and thickness of the NFF were elucidated. These findings provided new insights for the design of high-performance, tunable, sound-absorbing materials. The results demonstrated that the MPNM-NFF effectively combined two distinct sound absorption mechanisms, thereby expanding the effective absorption bandwidth, with particularly enhanced low-frequency sound absorption. Moreover, through algorithmic optimization of the structural parameters, targeted absorption of noise across different frequency bands was achieved, with the optimal average sound absorption coefficients reaching 0.70 in the low-frequency range, 0.91 in the mid-frequency range, and 0.82 in the full-frequency range. This research offered both theoretical foundations and practical guidance for the development of composite materials with high efficiency and broadband sound absorption characteristics, paving the way for innovative applications in noise control materials. Full article

This study investigated the effectiveness of two lamination methods for integrating electrospun nanofiber membranes with woven nylon fabric for personal protective applications. The first method used a thermoplastic urethane (TPU) nonwoven adhesive, while the second method incorporated both the adhesive and a yarn, with the yarn embedding by sewing. Lamination with the TPU nonwoven adhesive slightly improved the adhesion between the nanofiber membrane and the nylon fabric. However, it decreased the air permeability, with the degree of the decrease depending on the areal density of the TPU adhesive. As the areal density of the TPU increased from 10 g/m² to 30 g/m², the air permeability decreased from 107.6 mm/s to 43.4 mm/s. The lamination resulted in a slight increase in the filtration efficiency for oil aerosol particles (0.3 µm, PM0.3, at a flow rate of 32 L/min) to 96.4%, with a pressure drop of 83 Pa. Embedding non-fusible yarns in the laminate increased the nanofiber/fabric adhesion and permeability. Still, the filtration efficiency and pressure drop were reduced to 74.4% and 38 Pa, respectively, due to numerous pinholes formed in the nanofiber layer during the sewing process. Conversely, incorporating fusible TPU yarns not only improved the interlayer adhesion by 175% compared to using TPU fabric adhesive alone but also increased the air permeability to 136.1 mm/s. However, the filtration performance (87.7%, 72 Pa) was slightly lower than that of the unlaminated nanofiber/fabric pack because the TPU yarns sealed the pinholes during lamination. Lamination embedded with hot-melt yarns provides a versatile approach for combining nanofiber membranes with conventional fabrics. It can be used to develop nanofiber-functionalized textiles for a wide range of applications, including fire protection, electrical insulation, sound absorption, filtration, marine applications, and more. Full article

Investigating the impact of textile structure reinforcement on the mechanical characteristics of polymer composites produced by the compression molding technique was the goal of this work. An epoxy resin system served as the matrix, and various woven (plain, twill, basket), nonwoven (mat), and unidirectional (UD) textile structures made from E-glass fibers were employed as reinforcement elements. Compression molding of pre-impregnated textile materials (prepregs) was used to create the composites. The well-impregnated textile structures with resin into prepreg and the good interface between layers of the composites were verified during the manufacture of the polymer–textile composites using DSC thermal analysis and an SEM microscope. For the mechanical behavior, flexural properties were determined. The composite samples with unidirectional prepreg reinforcement have the highest longitudinal flexural strengths at roughly 900 MPa. The woven prepreg-based composite laminates show balanced flexural properties in both directions. Composites based on plane and basket prepregs have a flexural strength of about 450 MPa. Their flexural strength is over 20% lower than that of the samples made using twill prepreg. In both directions, nonwoven prepreg-reinforced composite samples show the least amount of resistance to bending stresses (flexural strength of roughly 150 MPa). Full article

This study presents an innovative approach to designing a shoe insole with enhanced durability, sustainability, and antibacterial properties. Needle-punched non-woven recycled polyester fabrics with three different GSMs (100, 200, and 300) were developed. The composite shoe insole was developed using non-woven fabric laminated with a polyurethane sheet to enhance durability. The fabrics were treated with an antibacterial finish with three different concentrations (5%, 10%, and 15%) and subjected to 5 and 10 washing cycles. The developed composites were evaluated against their relative hand value, abrasion resistance, tensile strength, antibacterial activity, and overall moisture management capability. Overall results reveal that the developed composite shoe insole is durable, sustainable, and presents no bacterial growth, demonstrating the insole’s hygienic effectiveness. Full article

Thin sound-absorbing materials are particularly desired in space-constrained applications, such as in the automotive industry. In this study, we theoretically analyzed the structure of relatively thin glass wool or polyester wool laminated with a nonpermeable polyethylene membrane and a permeable nonwoven fabric sheet. We also measured and compared the sound-absorption coefficients of these samples between experimental and theoretical values. The sound-absorption coefficient was derived using the transfer matrix method. The Rayleigh model was applied to describe the acoustic behavior of glass wool and nonwoven sheet, while the Miki model was used for polyester wool. Mathematical formulas were employed to model an air layer without damping and a vibrating membrane. These acoustic components were integrated into a transfer matrix framework to calculate the sound-absorption coefficient. The sound-absorption coefficients of glass wool and polyester wool were progressively enhanced by sequentially adding suitable nonwoven fabric and PE membranes. A sample approximately 10 mm thick, featuring permeable and nonpermeable membranes as outer layers of porous sound-absorbing material, achieved a sound-absorption coefficient equivalent to that of a sample occupying 20 mm thickness (10 mm of porous sound-absorbing material with a 10 mm back air layer). Full article

Lithium-ion batteries (LIBs) have an extremely diverse application nowadays as an environmentally friendly and renewable new energy storage technology. The porous structure of the separator, one essential component of LIBs, provides an ion transport channel for the migration of ions and directly affects the overall performance of the battery. In this work, we fabricated a composite separator (GOP-PH-ATP) via simply laminating an electrospun polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) nanofibrous membrane coated with attapulgite (ATP) nanoparticles onto a PP nonwoven microfibrous fabric, which exhibits a unique porous structure with a pore-size gradient along the thickness direction that ranges from tens of microns to hundreds of nanometers. As a result, besides the enhanced thermal stability given by the chosen materials, the GOP-PH-ATP separator was endowed with a superhigh porosity of ~95%, strong affinity with electrolyte, and great electrolyte uptake of ~760%, thus effectively enabling an ionic conductivity of 2.38 mS cm⁻¹ and a lithium-ion transference number of 0.62. Furthermore, the cell with the GOP-PH-ATP separator shows an excellent cycling performance with a capacity retention of 91.2% after 150 cycles at 1 C, suggesting that the composite separator with a pore-size gradient structure has great potential to be applied in LIBs. Full article

The rising industrial demand for environmentally friendly and sustainable materials has shifted the attention from synthetic to natural fibers. Natural fibers provide advantages like affordability, lightweight nature, and renewability. Jute fibers’ substantial production potential and cost-efficiency have propelled current research in this field. In this study, the mechanical behavior (tensile, flexural, and interlaminar shear properties) of plasma-treated jute composite laminates and the flexural behavior of jute fabric-reinforced sandwich composites were investigated. Non-woven mat fiber (MFC), jute fiber (JFC), dried jute fiber (DJFC), and plasma-treated jute fiber (TJFC) composite laminates, as well as sandwich composites consisting of jute fabric bio-based unsaturated polyester (UPE) composite as facing material and polyethylene terephthalate (PET70 and PET100) and polyvinyl chloride (PVC) as core materials were fabricated to compare their functional properties. Plasma treatment of jute composite laminate had a positive effect on some of the mechanical properties, which led to an improvement in Young’s modulus (7.17 GPa) and tensile strength (53.61 MPa) of 14% and 8.5%, respectively, as well as, in flexural strength (93.71 MPa) and flexural modulus (5.20 GPa) of 24% and 35%, respectively, compared to those of JFC. In addition, the results demonstrated that the flexural properties of jute sandwich composites can be significantly enhanced by incorporating PET100 foams as core materials. Full article

Hybrid composites are expanding applications in cutting-edge technology industries, which need materials capable of meeting combined properties in order to guarantee high performance and cost-effectiveness. This original article aimed for the first time to investigate the hybrid laminated composite thermal behavior, made of two types of fibers: synthetic Twaron^® fabric and natural curaua non-woven mat, reinforcing epoxy matrix. The composite processing was based on the ballistic helmets methodology from the North American Personal Armor System for Ground Troops, currently used by the Brazilian Army, aiming at reduced costs, total weight, and environmental impact associated with the material without compromising ballistic performance. Thermal properties of plain epoxy, aramid fabric, and curaua mat were evaluated, as well as the other five configurations of hybrid laminated composites. These properties were compared using thermogravimetric analysis (TGA) with its derivative (DTG), differential thermal analysis (DTA), and thermomechanical analysis (TMA). The results showed that the plain epoxy begins thermal degradation at 208 °C while the curaua mat at 231 °C and the aramid fabric at 477 °C. The hybrid laminated composites curves showed two or three inflections in terms of mass loss. The only sample that underwent thermal expansion was the five-aramid and three-curaua layers composite. In the third analyzed temperature interval, related to the glass transition temperature of the composites, there was, in general, an increasing thermal stability behavior. Full article

Medical product contamination has become a threatening issue against human health, which is the main reason why protective nonwoven fabrics have gained considerable attention. In the present, there is a soaring number of studies on establishing protection systems with nonwoven composites via needle punch. Meanwhile, the disadvantages of composites, such as poor mechanical performance and texture, impose restrictions. Hence, in this study, an eco-friendly method composed of needling, hot pressing, and lamination is applied to produce water-resistant, windproof, and antimicrobial Tencel/low-melting-point polyester-thermoplastic polyurethane/Triclosan (Tencel/LMPET–TPU/TCL) laminated membranes. Field-emission scanning electron microscope (SEM) images and FTIR show needle-punched Tencel/LMPET membranes successfully coated with TPU/TCL laminated membranes, thereby extensively improving nonwoven membranes in terms of water-resistant, windproof, and antimicrobial attributes. Parameters including needle punch depth, content of LMPET fibers, and concentration of TCL are changed during the production. Specifically, Tencel/LMPET–TPU/TCL–0.1 laminated nonwovens acquire good water resistance (100 kPa), outstanding windproof performance (<0.1 cm³/cm²/s), and good antimicrobial ability against Escherichia coli and Staphylococcus aureus. Made with a green production process that is pollution-free, the proposed products are windproof, water resistant, and antimicrobial, which ensures promising uses in the medical and protective textile fields. Full article

The carbon dioxide-assisted polymer compression method is used to create porous polymer products with laminated fiber sheets that are crimped in the presence of carbon dioxide. In this method, fibers are oriented in the sheet-spread direction, and the intersections of the upper and lower fibers are crimped, leading to several intersections within the porous product. This type of orientation in a porous material is anisotropic. A dye solution was injected via a syringe into a compression product made of poly(ethylene terephthalate) nonwoven fabric with an average fiber diameter of 8 μm. The anisotropy of permeation was evaluated using the aspect ratio of the vertical and horizontal permeation distances of a permeation area. The aspect ratio decreased monotonically with decreasing porosity; it was 2.73 for the 80-ply laminated product with a porosity of 0.63 and 2.33 for the 160-ply laminated product with a porosity of 0.25. A three-dimensional structural analysis using X-ray computed tomography revealed that as the compression ratio increased, the fiber-to-fiber connection increased due to the increase in adhesion points, resulting in decreased anisotropy of permeation. The anisotropy of permeation is essential data for analyzing the sustained release behavior of drug-loaded tablets for future fabrication. Full article

Particulate matter (PM) with a diameter of 0.3 µm is inhalable and brings great threats to human health. Traditional meltblown nonwovens used for air filtration need to be treated by high voltage corona charging, which has the problem of electrostatic dissipation and thus reduces the filtration efficiency. In this work, a kind of composite air-filter with high efficiency and low resistance was fabricated by alternating lamination of ultrathin electronspun nano-layer and melt-blown layer without corona charging treatment. The effects of fiber diameter, pore size, porosity, layer number, and weight on filtration performance were investigated. Meanwhile, the surface hydrophobicity, loading capacity, and storage stability of the composite filter were studied. The results indicate that the filters (18.5 gsm) laminated by 10 layers fiber-webs present excellent filtration efficiency (97.94%), low pressure drop (53.2 Pa), high quality factor (QF 0.073 Pa⁻¹), and high dust holding capacity (9.72 g/m²) for NaCl aerosol particles. Increasing the layers and reducing individual layer weight can significantly improve filtration efficiency and reduce pressure drop of the filter. The filtration efficiency decayed slightly from 97.94% to 96.48% after 80 days storage. The alternate arrangement of ultra-thin nano and melt-blown layers constructed a layer-by-layer interception and collaborative filtering effect in the composite filter, realizing the high filtration efficiency and low resistance without high voltage corona charging. These results provided new insights for the application of nonwoven fabrics in air filtration. Full article

Electrospun nanofibers are very popular in polymer nanocomposites because they have a high aspect ratio, a large surface area, and good mechanical properties, which gives them a broad range of uses. The application of nonwoven structures of electrospun nanofiber mats has historically been limited to enhancing the interlaminar responses of fiber-reinforced composites. However, the potential of oriented nanofibers to improve the characteristics of bulk matrices cannot be overstated. In this research, a multilayered laminate composite was created by introducing polyamide (PA6)-oriented nanofibers into an epoxy matrix in order to examine the effect of the nanofibers on the tensile and thermal characteristics of the nanocomposite. The specimens’ fracture surfaces were examined using scanning electron microscopy (SEM). Using differential scanning calorimetry (DSC) analysis, the thermal characteristics of the nanofiber-layered composites were investigated. The results demonstrated a 10.58% peak in the nanocomposites’ elastic modulus, which was compared to the numerical simulation and the analytical model. This work proposes a technique for the development of lightweight high-performance nanocomposites. Full article

Curaua, as a leaf-based natural fiber, appears to be a promising component with aramid fabric reinforcement of hybrid composites. This work deals with the investigation of flexural, impact and elastic properties of non-woven curaua–aramid fabric hybrid epoxy composites. Five configurations of hybrid composites in a curaua non-woven mat with an increasing quantity of layers, up to four layers, were laminated through the conventional hand lay-up method. The proposed configurations were idealized with at least 60 wt% reinforcement in the non-alternating configuration. As a result, it was observed that the flexural strength decreased by 33% and the flexural modulus by 56%. In addition, the energy absorbed in the Charpy impact also decreased in the same proportion as the replaced amount of aramid. Through the impulse excitation technique, it was possible observe that the replacement of the aramid layers with the curaua layers resulted in decreased elastic properties. However, reduction maps revealed proportional advantages in hybridizing the curaua with the aramid fiber. Moreover, the hybrid composite produced an almost continuous and homogeneous material, reducing the possibility of delamination and transverse deformation, which revealed an impact-resistant performance. Full article