Search Results (90)

Due to its superior maneuverability and concealment, the micro flapping-wing aircraft has great application prospects in both military and civilian fields. However, the development and optimization of lightweight materials have always been the key factors limiting performance enhancement. This paper designs the flapping mechanism of a single-degree-of-freedom miniature flapping wing aircraft. In this study, T800 carbon fiber composite material was used as the frame material. Three typical wing membrane materials, namely polyethylene terephthalate (PET), polyimide (PI), and non-woven kite fabric, were selected for comparative analysis. Three flapping wing configurations with different stiffness were proposed. These wings adopted carbon fiber composite material frames. The wing membrane material is bonded to the frame through a coating. Inspired by bionics, a flapping wing that mimics the membrane vein structure of insect wings is designed. By changing the type of membrane material and the distribution of carbon fiber composite materials on the wing, the stiffness of the flapping wing can be controlled, thereby affecting the mechanical properties of the flapping wing aircraft. The modal analysis of the flapping-wing structure was conducted using the finite element analysis method, and the experimental prototype was fabricated by using 3D printing technology. To evaluate the influence of different wing membrane materials on lift performance, a high-precision force measurement experimental platform was built, systematic tests were carried out, and the lift characteristics under different flapping frequencies were analyzed. Through computational modeling and experiments, it has been proven that under the same flapping wing frequency, the T800 carbon fiber composite material frame can significantly improve the stiffness and durability of the flapping wing. In addition, the selection of wing membrane materials has a significant impact on lift performance. Among the test materials, the PET wing film demonstrated excellent stability and lift performance under high-frequency conditions. This research provides crucial experimental evidence for the optimal selection of wing membrane materials for micro flapping-wing aircraft, verifies the application potential of T800 carbon fiber composite materials in micro flapping-wing aircraft, and opens up new avenues for the application of advanced composite materials in high-performance micro flapping-wing aircraft. Full article

With the rapid development of Internet of Things (IoT) and bioscience technology, wearable smart devices are developing toward advanced trends such as flexibility, convenience and environmental-friendliness. Poly (p-styrenesulfonic acid) (PSS), as a common template and dispersant, is indispensable in the polymerization of conductive polymers. However, the doping amount of PSS has a significant effect on the electrical conductivity of the polymer. Herein, different molar quantities of PSS were used to assist the polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer in a horseradish peroxidase/hydrogen peroxide (HRP/H₂O₂) low-temperature system to obtain conductive finishing solutions with more excellent electrical properties. Then, the polyester nonwoven fabric was immersed in the conductive finishing solution, and when the addition ratio of EDOT and PSS was 1:2, the conductive performance was optimal (3.27 KΩ cm⁻¹). Finally, the conductive fabric was assembled into a pressure sensor and a temperature sensor, which can transmit Morse code in the form of single-parameter (pressure response or temperature response) or collaboration. Overall, this research has great potential for production of poly(3,4-ethylenedioxythiophene) (PEDOT)-based composites and their applications in smart wearable device. Full article

Conventional filters for air filtration typically feature compact nonwoven structures, which not only lead to high pressure drop, significant energy consumption, and a decay in filtration efficacy, but are also uncleanable, resulting in substantial pollution upon disposal. In this study, filters with high-voltage electrostatic loading capability were developed with a dopamine binding layer to facilitate the establishment of an Ag conductive layer on the surface of ultraloose woven structure fabrics (pore size: 73.7 μm). The high-voltage-loaded woven structure filtration (VLWF) system was constructed with a negative-ion zone, a high-voltage filtration zone, and a grounded filter. The morphological, chemical, and electrical properties of the filters and the filtration performance of the VLWF system were evaluated. The single-pass filtration efficiencies for PM_2.5 and E. coli were 67.4% and 97.0%, respectively. Notably, the pressure drop was reduced to 6.2 Pa, and the quality factor reached 0.1810 Pa⁻¹ with no detectable ozone release. After three cycles of ultrasonic cleaning, approximately 58.4% of filtration efficiency was maintained without any increase in air resistance. The removal of PM_2.5 and microorganisms by this system was not solely reliant on blocking and electrostatic attraction but may also involve induced repulsion and biostructure inactivation. By integrating the ultraloose woven structure with high-voltage assistance, this VLWF system effectively balanced the requirements for high filtration efficacy and low air resistance. More importantly, this VLWF system provided a cleanable filter model that reduced the pollution associated with conventional disposable filters and lowered costs for customers. Full article

A novel cost-effective, rapid, and eco-friendly method was described for the removal of carbon dioxide (CO₂) from the gaseous emissions of gasoline engines. This involved the use of a sandwich filter (~10 cm diameter) made of a nonwoven poly (m-phenylene isophthalamide) (Nomex) fabric loaded with a thin layer of activated carbon. The optimized filter, with an activated carbon mass of 2.89 mg/cm², a thickness of 4.8 mm, and an air permeability of 0.5 cm³/cm²/s, was tested. A simple homemade sampling device equipped with solid-state electrochemical sensors to monitor the concentration levels of CO₂ before and after filtration of the emissions was utilized. The data were transmitted via a General Packet Radio Service (GPRS) link to an Internet of Things (IoT)-based gas monitoring system for remote management, and real-time data visualization. The proposed device achieved a 70 ± 3.4% CO₂-removal efficiency within 7 min of operation. Characterization of the filter was conducted using a high-resolution scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Brunauer–Emmett–Teller (BET) analysis. The effects of loaded activated carbon mass, fabric type, filter porosity, gaseous removal time, and adsorption kinetics were also examined. The proposed filter displayed several advantages, including simplicity, compactness, dry design, ease of regeneration, scalability, durability, low cost, and good efficiency. Heat resistance, fire retardancy, mechanical stability, and the ability to remove other gasoline combustion products such as CO, SO_x, NO_x, VOCs, and particulates were also offered. The filtration system enabled both in situ and on-line CO₂ real-time continuous emission monitoring. Full article

Fluid dynamics modeling was conducted for the supply unit of a Powered Air-Purifying Respirator (PAPR) consisting of a nonwoven fabric filter and a pump, as well as for the exhaust filter (nonwoven fabric). The supply flow rate Q₁ was modeled as a function of the differential pressure ΔP and the duty value d of the PWM control under a constant pump voltage of V = 12.0 [V]. In contrast, the exhaust flow rate Q₂ was modeled solely as a function of ΔP. To simulate the pressurized hood compartment of the PAPR, a pressure buffer and a connected “respiratory airflow simulator” (a piston–cylinder mechanism) were developed. The supply unit and exhaust filter were connected to this pressure buffer, and simulated respiratory flow was introduced as an external disturbance flow. Under these conditions, it was demonstrated that the respiratory state—i.e., the expiratory state (flow from the simulator to the pressure buffer) and the inspiratory state (flow from the pressure buffer to the simulator)—can be estimated from the differential pressure ΔP, the pump voltage V, and the PWM duty value d, with respect to the disturbance flow generated by the respiratory airflow simulator. It was also confirmed that such respiratory state estimation remains valid even when the duty value d of the pump is being actively modulated to control the internal pressure of the PAPR hood. Furthermore, based on the estimated respiratory states, a theoretical investigation was conducted on constant pressure control inside the PAPR and on the inverse pressure control aimed at supporting respiratory activity—namely, pressure control that assists breathing by depressurizing when expiratory motion is detected and pressurizing when inspiratory motion is detected. This study was conducted as part of a research and development project on public-oriented PAPR systems, which are being explored as alternatives to lockdown measures in response to airborne infectious diseases such as COVID-19. The present work specifically focused on improving the wearing comfort of the PAPR. Full article

This study was conducted to improve the sound absorption dips in nonwoven fabric sheets with a back air space. Considering the particle velocity distribution in the back air space, another nonwoven sheet was added to divide the air space into layers. The sound absorption coefficient of the sound-absorbing structure was theoretically derived using the transfer matrix method. The nonwoven sheet model with the Rayleigh model and the air space behind the nonwoven sheet were mathematically represented using the transfer matrix. The transfer function method was employed to combine the transfer matrices to obtain the sound absorption coefficient. A two-microphone acoustic impedance tube was used to measure the sound absorption coefficient, and the theoretical and experimental values were compared. The sound absorption dip of the first order was improved by placing a nonwoven sheet at a position half the thickness of the back air space. It was theoretically predicted that placing the nonwoven sheet at 1/4 of the back air space thickness from the rigid wall would improve the first- and second-order sound absorption dips. By selecting the conditions, a similar trend was observed during the experiments. The study shows that the higher the ventilation resistance of the added nonwoven fabric sheet, the more improved the sound absorption dip. Full article

Bacterial cellulose (BC) synthesized by Acetobacter xylinum has gained significant attention due to its unique structural and functional properties. This study focuses on the simple, facile, and cost-effective synthesis of bacterial cellulose films from Acetobacter xylinum and evaluates their impact on selected properties. The BC films were prepared through a series of controlled fermentation, purification, and drying processes, optimizing their porosity and structural integrity with different stabilization forms (the BC films supported by polyester nonwoven (PES NW) fabric) by a static culture method keeping with the sustainability. The selected properties like density, porosity, surface roughness, thermal conductivity, and the wetting properties of surfaces are tested. These properties were chosen because they significantly impact the performance of BC aerogels in the potential application of aerogels in biomedical, insulation, and filtration industries. The results indicated that the synthesized BC aerogels exhibit a highly porous network, lightweight structure, and excellent thermal conductivity, making them suitable for advanced material applications. This research highlights the potential of bacterial cellulose aerogels as sustainable (without any additives/chemicals) and high-performance materials, paving the way for further advancements in bio-based aerogels. Full article

Graphene-based textile pressure sensors are emerging as promising candidates for wearable sensing applications due to their high sensitivity, mechanical flexibility, and low energy consumption. This study investigates the design, fabrication, and electromechanical behaviour of graphene-coated nonwoven textile-based piezoresistive pressure sensors, focusing on the impact of different electrode materials and fabrication techniques. Three distinct sensor fabrication methods—drop casting, electrospinning, and electro-spraying—were employed to impregnate graphene onto nonwoven textile substrates, with silver-coated textile electrodes integrated to enhance conductivity. The fabricated sensors were characterised for their morphology (SEM), chemical composition (FTIR), and electromechanical response under cyclic compressive loading. The results indicate that the drop-cast sensors exhibited the lowest initial resistance (~0.15 kΩ) and highest sensitivity (10.5 kPa⁻¹) due to their higher graphene content and superior electrical connectivity. Electro-spun and electro-sprayed sensors demonstrated increased porosity and greater resistance fluctuations, highlighting the role of fabrication methods in sensor performance. Additionally, the silver-coated knitted electrodes provided the most stable electrical response, while spun-bonded and powder-bonded nonwoven electrodes exhibited higher hysteresis and resistance drift. These findings offer valuable insights into the optimisation of graphene-based textile pressure sensors for wearable health monitoring and smart textile applications, paving the way for scalable, low-power sensing solutions. Full article

Mulching is a widely adopted practice in vegetable cultivation globally. This technique employs various plastic materials, such as polyethylene (PE) film or polypropylene (PP) nonwoven fabric, with an increasing trend toward the use of biodegradable materials. Between 2014 and 2016, field experiments were conducted to evaluate the performance of the small-fruited tomato Intrigo F1 cultivated using synthetic mulches. The trials, designed as single-factor experiments employing a randomized block layout with three replicates, assessed plant morphological traits, yield, and the biological value of the tomato fruits. Weather conditions and the type of mulch applied had a pronounced influence on the quality of tomato plants and yield. Compared to the control, the use of black, red, and aluminum PE films and brown PP resulted in a 7.2% increase in plant height. All mulching treatments, except white film, increased the lateral spread of the plants by an average of 24.2%. Plants cultivated on red PE film exhibited a 26.4% increase in leaf count with respect to the control. Mulched treatments achieved an average increase of 19.6% in marketable yield. The highest marketable fruit yield was recorded with black nonwoven fabric mulch. Mulching had a significant effect on the chemical composition of tomato fruits. Fruits on biodegradable foil had the most potassium, lycopene, and polyphenols. Full article

Global warming and climate change demand rapid and swift action in terms of reducing resource consumption, gas emissions, and waste generation. The textile industry is responsible for a large share of global pollution; therefore, to define a route to tackle part of the issue, a literature review on the current state of research in the field of recycling silk waste was conducted. The methods used to recover, process, and characterize silk waste fibers were summarized. The aim of this work was to investigate the possible applications of recycled silk waste in the field of composite materials for load bearing applications. In this sense, some prominent studies in the field of silk-based composites were reported, favoring thermoplastic materials for sustainability reasons. Studies on nonwoven silk waste fabrics were covered as well, finding an abundance of results but no applications as a reinforcement for composite materials. In a circular economy approach, we believe that the combination of nonwoven silk waste fabrics, thermoplastic polymers, and possibly hybridization with other fibers from sustainable sources could be beneficial and could lead to green and high-performance products. The aim of this work was to summarize the information available so far and help define a route in that direction. Full article

Air pollution is currently the most significant environmental factor posing a threat to the health and lives of European residents. It is a key cause of poor health, particularly respiratory and cardiovascular diseases. The primary aim of the study was to numerically determine the impact of the air purifier model’s geometry on the distribution of air within a room and to conduct experimental tests on the filtration efficiency and preliminary antibacterial activity of filtration composites. The scope of the work included designing an air purifier model in the form of a pendant lamp and performing computer simulations in Ansys software to identify the optimal shape. The experimental research focused on developing filtration composites consisting of nonwoven fabric with an active hydrosol layer, meltblown nonwovens and a carbon filter. The study results showed that the SMMS composite with 50% thyme and carbon nonwoven exhibited the highest filtration efficiency for both small and large particles. Full article

Building envelopes with natural fibers are the future of sustainable construction, combining ecology and energy efficiency. The geopolymer building envelope was reinforced with innovative composite bars and two types of natural insulation (coconut mats and flax/hemp non-woven fabrics) were used as the core material. A 10 mol sodium hydroxide solution with an aqueous sodium silicate solution was used for the alkaline activation of the geopolymers. The purpose of this study was to confirm the feasibility of producing geopolymer composites with insulating layers made of renewable materials, which would have compressive strengths like those of C25/30-grade concrete and thermal conductivity coefficients like those of lightweight concrete. This publication presents the results of physicochemical tests on the base materials (oxide (XRF) and mineral phase (XRD) analysis as well as morphology and EDS) and studies the physical (density measurements), mechanical (flexural and compressive strength tests) and insulating properties (thermal conductivity measurements) of the finished sandwich partitions. The composites achieved a flexural strength of 7 MPa, a compressive strength of up to 30 MPa and a decrease in the thermal conductivity coefficient of about 60%. The research demonstrates contribution to sustainable construction by developing geopolymer composites, offering both structural integrity and superior thermal insulation. This innovation not only reduces reliance on traditional, carbon-intensive materials but also promotes the use of eco-friendly resources, significantly lowering the carbon footprint of construction. The integration of natural fibers into geopolymer matrices addresses key environmental concerns, advancing a rapidly growing field that aligns with global efforts toward energy efficiency, waste reduction, and circular economy principles in building design. Full article

The long-term use of air filters causes dust to accumulate on their surfaces or fill in the fibers of their internal filtering materials over time, thereby greatly reducing their effectiveness; therefore, the cleaning and replacement of air filter materials in public buildings are of great concern. The most commonly used non-woven fabric materials currently on the market are taken as the research object for this work, in which experiments are conducted on ultrasonic cleaning parameters, cleaning performance, regeneration effects, etc. The results showed that the best cleaning performance was achieved when the ultrasonic cleaning parameter was set to 120 W, and the cleaning time to 11.2 s, with a significant effect on particulate matter with a particle size of less than 2.5 μm. Under the premise of repeated dust containment, when PM₁₀, PM_2.5, and PM_1.0 are cleaned nine, six, and seven times, respectively, the filtration performance for these particles can also recover to over 85% of the performance of the fresh filter material before cleaning; however, after ten ultrasonic cleanings, the filtration resistance decreased within the range of 4.6~20.7 Pa. In this study, we aim to effectively reduce the replacement of old filters and the generation of incineration pollution, thereby reducing carbon-dioxide-equivalent emissions and providing a reference value for achieving the efficient utilization of filter materials in public buildings under the dual carbon target. Full article

This article discusses the important issue of designing textiles for electrostatic discharge (ESD) protection. ESD protective textiles are used to prevent the failure of electronic circuits. They also safeguard human health and life in explosive environments. The textiles are usually made of woven, knitted, or nonwoven fabrics incorporating a grid or strips of conductive fibers within a base material made of cotton, polyester, or blends of these materials. Various testing standards have been developed to evaluate the suitability of textiles for ESD protection. One of the most widely used is the EN 1149-3 standard, which outlines procedures for recording charge decay plots. The procedure can be used to evaluate all types of textiles. This paper discusses models corresponding to the standard developed in the general-purpose COMSOL Multiphysics software. Using the advanced numerical methods of the software, it is possible to graphically present the phenomena occurring during the application of the standard procedure and to determine the influence of the grid and material parameters on the shape of the charge decay plots. Furthermore, this article compares charge decay plots and shielding effectiveness measured in an accredited laboratory with simulation results. Full article

This research used end-of-use cotton apparel to develop mulch mats, a type of agrotextiles. The researchers collected and sorted end-of-use garments to obtain cotton textile waste. These end-of-use garments were deconstructed to obtain shredded textiles and big pieces of textiles. Using the textiles from deconstructed end-of-use garments, together with a small amount of new cotton fibers, the researchers used a Feltloom to develop needle-punched nonwoven fabrics that can be used as mulch mats. The researchers tested textile properties of these mulch mats and conducted agricultural field tests for weed control and pot tests for biodegradation. The researchers also tested the mulch mats’ soil moisture infiltration, and impact on water evaporation. The nonwoven mulch mats made from end-of-use garments have excellent weed inhibition capability and biodegradability. Compared to plastic mulch sheet, the nonwoven mulch mats are better for water utilization in rainfall watering and sprinkle irrigation but poorer in water conservation in drip irrigation. Considering durability, biodegradability, and soil temperature regulation, it is recommended to use 100% cotton and felt four times to produce mulch mats from end-of-use garments. Full article