Fiber Mats Research Articles

Utilization of response surface methodology to optimize the mechanical behaviour of flax/nano TiO2/Epoxy based hybrid composites under liquid nitrogen environment

Linum usitatissimum commonly known as flax fibers, emerges as a promising reinforcement phase for artificial polymer resins, boasting ecological benefits, low density, and easy accessibility. However, the mechanical behavior of such composites hinges crucially on factors such as fiber mat thickness, nanoTiO2 filler content, and the application of cryogenic treatment. Addressing this complex interplay, this study employs a hand lay-up technique for composite construction, subjecting nanocomposite plates to the challenging liquid nitrogen conditions at 77 K post-manufacture. Recognizing the need for an optimized approach, Response Surface Methodology (RSM) based on Box-Benhken designs is employed to enhance the mixing features of linum usitatissimum polymer composites. The study calculates anticipated mechanical strength values through rigorous ANOVA inferential analysis, uncovering the pivotal roles played by fiber mat thickness, nanofiller content, and cryogenic treatment in the two feature interactions (2FI) model components. The methodology proves robust with high R2 values (0.9670 for tensile, 0.9845 for flexural, and 0.9670 for interlaminar shear strength) consistently aligning with experimental findings. The study culminates in identifying optimized parameters for maximal mechanical properties—300 gsm flax fiber thickness, 5 wt.% nano TiO2 concentration, and a 15-min cryogenic treatment—a result that advances our understanding of fundamental factors influencing composite performance and provides practical guidelines for applications in fields requiring superior mechanical strength in challenging environments.

Predicting the tensile and compressive modulus of electrospun fiber mat‐reinforced hydrogels using the Halpin–Tsai equations

AbstractThe reinforcement of mechanically‐weak hydrogels to yield composites with increased stiffness, strength, or toughness is a well‐established approach. In particular, introducing electrospun nanofibers into hydrogels is a common strategy for biomedical applications, as the resulting hierarchical structure mimics biology and allows for control over fiber diameter and alignment and tuning of mechanical properties. However, further study of the link between the constituent materials and the mechanical properties of the composite is uncommon. One potential model to understand the mechanical properties of fiber‐reinforced hydrogels involves the Halpin–Tsai equations, which relate the modulus values of the fibers and hydrogel matrix and the fiber volume fraction, to the modulus of the composite. To assess the application of this model to fiber‐reinforced hydrogels, predicted values were compared with experimental values from mechanical testing of a poly(ethylene glycol) (PEG) matrix reinforced with an electrospun polycaprolactone (PCL) fiber mat. Although the equations described these systems well in tension, providing a facile approach to identify a fiber volume fraction that will achieve a desired modulus, the Halpin–Tsai approach was less successful under compression. This study motivates additional investigation of the role of structural features of hydrogel composites in determining mechanical properties to enable design of materials for specific applications.

Development of eco-friendly and robust structural materials via binder-free lamination of waste biomass with help of finite element method

To alleviate the environmental pressure, it is of great significance to develop the green and sustainable structural materials by utilization of waste biomass. In this work, an eco-friendly, high-strength, superhydrophobic, and thermally stable material was fabricated through a scalable binder-free lamination method using waste biomass (e.g., wood residues, crop straw, and waste paperboard). The waste biomass was separated and molded into fiber mats by a clean pulping process, and then laminated without adhesives. The finite element method (FEM) was adopted to visually observe fracture behaviors and detect the weakest zones. The utilization of FEM to enhance the mechanical strength is unique in productions of traditional biomass composites. The weakest zones were reinforced by the H2O2 spraying approach, and the flexural strength (FS) was improved from 80.12 to 120.35 MPa. The moisture content (MC) in the mat was used for regulating the softening of cellulosic fibers. In virtue of the water-induced plasticization, the laminated materials showed a high internal bonding strength (IBS) of 2.24 MPa and excellent FS of 134.81 MPa. Being benefitted from the silica modification, the materials exhibited a superhydrophobic surface with the high water contact angle (154.1°), good dimensional stability (a thickness swelling of 14.8%), and superior mechanical stability (remained 94.3% FS after two months of ultraviolet radiation). This work provides a new strategy to develop green and sustainable structural materials for buildings, furniture, and related applications.

Tailorable mechanical and degradation properties of KCl-reticulated and BDDE-crosslinked PCL/chitosan/κ-carrageenan electrospun fibers for biomedical applications: Effect of the crosslinking-reticulation synergy

The development of intricated and interconnected porous mats is desired for many applications in biomedicine and other relevant fields. The mats that comprise the use of natural, bioactive, and biodegradable polymers are the focus of current research activities. In the present work, crosslinked fibers with improved characteristics were produced by incorporating 1,4-butanediol diglycidyl ether (BDDE) into a polymer formulation containing polycaprolactone (PCL), chitosan (CS), and κappa-carrageenan (κ-C). A slight variation of formic acid (FA)/acetic acid (AA) ratio used as a solvent system, significantly affected the characteristics of the produced fiber mats. Both polysaccharides and BDDE played a major role in tailoring mechanical properties when fibrous scaffolds were reticulated under KCl-mediated basic conditions for determined periods of time at 50 °C. In vitro biological assessment of the electrospun fiber mats revealed proliferation of MC3T3-E1 cells when incubated for 1 and 7 days. After staining the cells with 4′,6-diamidino-2-phenylindole (DAPI)/rhodamine phalloidin an autofluorescence response was observed by fluorescence microscopy in the scaffold manufactured using a solvent with higher FA/AA ratio due to the formation of microfibers. The results demonstrated the potential of the BDDE-crosslinked PCL/CS/κ-C electrospun fibers as promising materials for biomedical applications that may include soft and bone tissue regeneration.

Socio-ecological risk factors associated with human flea infestations of rural household in plague-endemic areas of Madagascar.

Plague is a flea-borne fatal disease caused by the bacterium Yersinia pestis, which persists in rural Madagascar. Although fleas parasitizing rats are considered the primary vectors of Y. pestis, the human flea, Pulex irritans, is abundant in human habitations in Madagascar, and has been found naturally infected by the plague bacterium during outbreaks. While P. irritans may therefore play a role in plague transmission if present in plague endemic areas, the factors associated with infestation and human exposure within such regions are little explored. To determine the socio-ecological risk factors associated with P. irritans infestation in rural households in plague-endemic areas of Madagascar, we used a mixed-methods approach, integrating results from P. irritans sampling, a household survey instrument, and an observational checklist. Using previously published vectorial capacity data, the minimal P. irritans index required for interhuman bubonic plague transmission was modeled to determine whether household infestations were enough to pose a plague transmission risk. Socio-ecological risk factors associated with a high P. irritans index were then identified for enrolled households using generalized linear models. Household flea abundance was also modeled using the same set of predictors. A high P. irritans index occurred in approximately one third of households and was primarily associated with having a traditional dirt floor covered with a plant fiber mat. Interventions targeting home improvement and livestock housing management may alleviate flea abundance and plague risk in rural villages experiencing high P. irritans infestation. As plague-control resources are limited in developing countries such as Madagascar, identifying the household parameters and human behaviors favoring flea abundance, such as those identified in this study, are key to developing preventive measures that can be implemented at the community level.

Heat‐Resistant Air Filters Based on Self‐Sustained Electrostatic and Antibacterial Polyimide/Silver Fiber Mats

AbstractAir pollution containing microorganisms poses a major hazard to human health. It is critical to develop air filters that are both highly efficient for indoor use and suitable for use in industrial settings. Developing long‐lasting electrostatic force‐assisted filtration while keeping high‐temperature resistance and antibacterial qualities is still challenging. Here, centrifugal spinning is used to fabricate fiber mats consisting of polyimide with silver incorporation (PI/Ag). The electrostatic force remained over –700 V after 330 days. The strong electrostatic effect improves the filtration efficiency, resulting in a high PM0.3 removal efficiency of 99.1% with a low‐pressure drop of 103.67 Pa. The high filtration efficiency remains above 91.3% for PM0.3 after placing it for 330 days and heating it at 280 °C. The PI/Ag fiber mats also show antimicrobial properties against the E. coli (Gram‐negative) and S. aureus (Gram‐positive) with prominent bacteriostatic zones >1.2 mm. The PI/Ag fiber mat filters are expected to have great potential for multi‐scenario air filtration.

Stress-strain behavior of square concrete columns confined with hybrid B-CSM composites and development of novel prediction models

This paper presents a comprehensive investigation into the behavior of concrete confined with hybrid Basalt and Chopped Strand Mat (B-CSM) fibers. The newly proposed B-CSM confinement technique substantially enhances the brittle compressive stress-strain behavior, leading to a noteworthy increase in peak strength (approximately 90%) and ultimate strain (approximately 461 %). The efficiency of B-CSM confinement is affected by the strength of plain concrete, with lower-strength specimens indicating a more pronounced enhancement. The performance of existing analytical models for FRP confinement in predicting ultimate strength and strain in B-CSM confined concrete is assessed, highlighting the need for tailored models. Regression-based equations are proposed for characteristic points along the stress-strain curve, enabling accurate prediction of material behavior. The predicted stress-strain curves exhibit a high level of agreement with experimental results. These findings provide valuable insights for the design and application of B-CSM confinement techniques in structural engineering, facilitating improved performance and ductility of concrete structures under compressive loading conditions.

Stress Intensity Factor of E-Glass Fiber Reinforced Polyester Composites

In order to analyze the stress concentration impact, intensity close to the zone of the crack tip, this work examines the in-plane SIF(SIF) of composite plates utilizing measured crack tip opening displacement (CTOD). The test specimens' E-glass fiber mats were arranged in various ply configurations. The ASTM standards utilized for researching mode I fracture of composite materials served as the foundation for the compact tension (CT) specimen. The mode I, KI Stress intensity factor (SIF), and critical stress, c, were calculated for each specimen along the fracture length propagation based on the experiments. It was found that the SIF is directly proportional with fracture length, or a/W, for all E-glass fiber laminate cases tested. The KIC is often higher in thinner laminates. The presence of woven roving increases the SIF and hence the toughness of the laminate.

Sustainable energy harvesting and breath sensing with electrospun triboelectric nylon-6

A high-performance triboelectric nanogenerator (TENG) has been developed for breath sensing applications, utilizing tribopositive electrospun nylon-6 nanofibers and tribonegative fluorinated ethylene propylene (FEP). The optimization toward the development of electrospun nylon-6-based TENG includes a range of factors such as the applied force and frequency on tribo responses, the thickness of the fiber mat, the concentration of nylon-6 in the fiber mats, and the selection of the tribonegative material for pairing with nylon-6 nanofiber. Among these parameters, the nanofiber prepared with 18 wt% nylon-6, characterized by a uniform fiber distribution, the highest surface area of 55.69 m2 g−1, and an optimal thickness of 0.169 mm, demonstrated excellent TENG performance, among others. The TENG module constructed using nanofiber in a 4 cm2 area showed the TENG responses of more than 30 μA short-circuit current, 200 V open-circuit voltage, and 90 nC charge when hand-pressed. It achieved a substantial power density of 890 mW m−2 at 20 MΩ by applying a constant force of 10 N at a 10 Hz frequency. Charging a 1 μF capacitor to approximately 30.1 V in just 30 s highlights the potential of electrospun nylon-6 as a promising material for nanogenerator energy harvesting and sensing applications. The TENG device was found to be sufficient to power small, portable electronics such as LEDs and digital watch displays. A wearable belt was fabricated to showcase its breath-sensing capabilities by pairing it with FEP. The microcontroller connected to the TENG in the wearable belt is used to analyze the output produced through breathing patterns, subsequently activating a buzzer and LED by the nature of the breathing.

Morphological, Mechanical and Thermal Characteristics of PLA /<i>Cocos nucifera</i> L Husk and PLA/<i>Zea mays</i> Chaff Lignin Fibre Mats Composites

Polylactide (PLA) is a biodegradable polymer with low elongation which limits its use in some applications. The incorporation of biowaste particles has been employed to improve its properties. This work thus examines the impact of lignin particles reinforced on electrospun PLA fibre mats. Acid hydrolysis (1M of HCl at 60 and 100 oC for 2 and 4 h was used to extract lignin from Cocos nucifera L (CNHL) and Zea Mays Chaff (CCL). Lignin particles were added to molten PLA, stirred, and electrospun at 26 kV, using a static aluminum collector plate placed at 121mm from the spinneret tip. Morphological examination reveals that fibre diameter of neat PLA (9.7 µm) increased from 107 – 285 % with the additions of reinforcements. Maximum tensile strength of 1.03 MPa is recorded for PLA/CNHL 60oC /2 h. This composite maintains the highest elongation of 0.069 % compared to neat PLA (0.046 %). X-Ray diffractometer (XRD) result informs that the crystallinity of neat PLA (67.6 %) improves by 3%, with the use of CNHL 60 oC/ 2 h. Thermo gravimetric analysis (TGA) result shows that both fibre composites possess better thermal stability (380 oC) compared to reinforcing PLA fibre (319 oC).

Effect of stacking order on the properties of hybrid palm sheath/polyester fiber felt‐reinforced polymer composite laminates

AbstractNatural fiber‐reinforced composites exhibit excellent mechanical properties. However, achieving a balance between excellent mechanical properties and optimal acoustic performance remains a challenge. In this study, four composite laminates with different stacking orders were fabricated using polyester fiber mats (WFs) and palm sheaths (WPs) through a hot‐press process. Moreover, the effects of different stacking orders on the mechanical and acoustic properties of the composite were investigated. The results revealed that the incorporation of polyester fiber felts and the modification of the layup sequence of WP and polyester fiber felts significantly improved the mechanical and acoustic properties of the composites. Scanning electron microscopy images revealed a strong bonding between palm fibers and polyester fibers at the epoxy resin interface. Compared with pure palm fiber composites, the alternately stacked palm fibers and polyester fibers (WP/WP/WF/WP/WF) exhibited the highest mechanical properties, with a significant enhancement of 142.67% and 16.90% in flexural and tensile strengths, respectively. Additionally, the peak absorption coefficient of polyester fiber felts, positioned in the surface layer of the composite material, within the 2580–3400 Hz frequency band significantly increased from 0.07 to 0.44. Therefore, this study indicates that modifying the stacking order improves the mechanical and acoustic properties of the composites, making them suitable for use in acoustic engineering materials for buildings and decorative panels for furniture, including perforated panels and acoustic screens.Highlights The fabric‐like textured structure significantly enhanced the overall performance of the composites. The stacking order significantly influenced the overall properties of the composite. Alternately stacked polyester fiber felts and palm fibers exhibited excellent mechanical performance. The polyester fiber felts positioned on the surface layer of the composites exhibited superior mechanical performance. A laminate with “green” attributes and good acoustic properties was fabricated.

Fabrication and properties of Si3N4f/RBSN porous ceramic composite

Porous Si3N4 has excellent properties such as high temperature resistance, corrosion resistance, high porosity, and high specific surface area, but the inherent brittleness limits the application of Si3N4 in some special environments. Si3N4f/RBSN porous ceramic composites were prepared by reaction bonding method using reaction-bonded silicon nitride(RBSN) as the matrix and continuous Si3N4 fibers (fiber mats) as the reinforcement. The results show that the composite with Si/Si3N4 = 70:30 in the raw material has a superior nitridation rate and flexural strength of 96.5% and 23.5 MPa, respectively. The nitridation process of the Si3N4f/RBSN matrix is dominated by the vapour-phase reaction between SiO and N2, and the products are mainly α-Si3N4 whiskers. The residual flexural strength of the composites is essentially unchanged after 10 thermal cycles in air at 800 °C. The composites have excellent thermal shock resistance and can be used as the reusable crucible.

Porous Ti3C2Tx MXene nanosheets sandwiched between polyimide fiber mats for electromagnetic interference shielding

Porous Ti3C2Tx MXene nanosheets sandwiched between polyimide fiber mats for electromagnetic interference shielding

Innovative Electrospun Nanofiber Mats Based on Polylactic Acid Composited with Silver Nanoparticles for Medical Applications.

Nanofibers are some of the most attractive materials that can modify functionalities for developing new kinds of specific applications and are mainly used as a biomedical material. Herein, we designed and prepared antibacterial nonwoven fiber mats of PLA and PLA composited with Ag nanoparticles by electrospinning. The effects of varying filler contents on their chemical, surface morphology, thermal, water absorbency, and antibacterial properties were investigated using FTIR, SEM/EDS, DSC, swelling ratio, and qualitative and quantitative antibacterial tests. FTIR and EDS spectra indicated that Ag nanoparticles were incorporated in the PLA without chemical bonding. SEM revealed that the average diameter of the PLA nanofibers containing the Ag nanoparticles was more significant than those without those particles. In addition, fiber diameters are proportional to the amount of Ag nanoparticle contents. DSC indicated that the Ag nanoparticles can be incorporated within the PLA matrix without strongly affecting their thermal properties. Moreover, the crystallinity of the composite nonwoven fiber mats was higher than those of fiber mats in the neat PLA. However, TGA revealed that the loaded Ag can improve the thermal stability of the PLA electrospun fiber mats. Accordingly, the antibacterial activities revealed that all the composite nanofiber mats exhibited excellent resistance against S. aureus and E. coli bacterial strains. In addition, in the cell toxicity study, all produced hybrids of nonwoven fiber mats induced a reduction in cell viability for the L929 fibroblast cells. Our results suggest that the designed and prepared nonwoven fiber mats may have good potential for use in the biomedical field, particularly in wound dressing applications.

Flexible Magnetocaloric Fiber Mats for Room-Temperature Energy Applications.

Currently, magnetocaloric refrigeration technologies are emerging as ecofriendly and more energy-efficient alternatives to conventional expansion-compression systems. However, major challenges remain. A particular concern is the mechanical properties of magnetocaloric materials, namely, their fatigue under cycling and difficulty in processing and shaping. Nevertheless, in the past few years, using multistimuli thermodynamic cycles with multicaloric refrigerants has led to higher heat-pumping efficiencies. To address simultaneously the challenges and develop a multicaloric material, in this work, we have prepared magnetocaloric-based flexible composite mats composed of micrometric electroactive (EA) polyvinylidene fluoride (PVDF) fibers with embedded magnetocaloric/strictive La(Fe,Si)13 particles by the simple and cost-effective electrospinning technique. The composite's structural characterization, using X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and measurements of the local-scale piezoresponse, revealed a cubic NaZn13-type structure of the La(Fe,Si)13 phase and the formation of the dominant polar β-phase of the PVDF polymer. The PVDF-La(Fe,Si)13 composite showed an enhancement of the longitudinal piezoelectric coefficient (effective d33) (-11.01 pm/V) compared with the single PVDF fiber matrix (-9.36 pm/V). The main magnetic properties of La(Fe,Si)13 powder were retained in the PVDF-La(Fe,Si)13 composite, including its giant magnetocaloric effect. By retaining the unique magnetic properties of La(Fe,Si)13 embedded in the electroactive piezoelectric polymer fiber mats, we have designed a flexible, easily shapeable, and multifunctional composite enabling its potential application in multicaloric heat-pumping devices and other sensing and actuating devices.

Experimental study on the optimum number of layers of fiber mats for gas-liquid coalescer

Experimental study on the optimum number of layers of fiber mats for gas-liquid coalescer

Spider-Silk-like Fiber Mat-Covered Polypropylene Warp-Knitted Hernia Mesh for Inhibition of Fibrosis under Dynamic Environment.

Hernia surgery is a widely performed procedure, and the use of a polypropylene mesh is considered the standard approach. However, the mesh often leads to complications, including the development of scar tissue that wraps around the mesh and causes it to shrink. Consequently, there is a need to investigate the relationship between the mesh and scar formation as well as to develop a hernia mesh that can prevent fibrosis. In this study, three different commercial polypropylene hernia meshes were examined to explore the connection between the fabric structure and mechanical properties. In vitro dynamic culture was used to investigate the mechanism by which the mechanical properties of the mesh in a dynamic environment affect cell differentiation. Additionally, electrospinning was employed to create polycaprolactone spider-silk-like fiber mats to achieve mechanical energy dissipation in dynamic conditions. These fiber mats were then combined with the preferred hernia mesh. The results demonstrated that the composite mesh could reduce the activation of fibroblast mechanical signaling pathways and inhibit its differentiation into myofibroblasts in dynamic environments.

Layered ZrO2/SiO2 aerogel composite fibrous flexibility membrane for thermal insulation and sound absorption

AbstractAs promising candidates for widespread application, advanced ceramic fiber mats with robust mechanical properties are urgently needed. However, the brittleness, fatigue failure, and large density of ceramic fiber pose significant obstacles to its practical application. Herein, a novel SiO2 aerogel/ZrO2 composite nanofibrous membrane (SZCNFM) with excellent flexibility was prepared by introducing SiO2 aerogel nanoparticles into ZrO2 nanofiber via simple co‐electrospinning. The developed tetragonal zirconia phase without changing up to 1200°C endows SZCNFM material with excellent thermal stability. Furthermore, the as‐prepared membranes exhibit fatigue resistance ability which can maintain 98% of the original stress after 100 buckling cycle tests. The addition of mesoporous structure aerogel reduces the heat transfer of the nanofibrous membrane, giving its low thermal conductivity (30 mW/m/K) and low‐frequency sound absorption (noise reduction coefficient of 0.52). Combined with the high‐temperature resistance, low thermal conductivity and excellent sound‐absorption ability make it a promising material for heat insulation and acoustic absorption.

Poly (vinyl alcohol) based carbon nanofibers as freestanding anodes for lithium‐ion batteries

AbstractIn this study, we investigated the iodination process for the preparation of water‐soluble polyvinyl alcohol (PVA)‐based carbon nanofibers (CNFs) and their electrochemical properties. Iodinated nanofibers were carbonized at different temperatures (600°C, 800°C) under an argon (Ar) atmosphere. Morphology and physical properties of fiber mats were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetric analysis (TGA), while electrical conductivity measurements were done using four probes. As a freestanding anode in half‐cell lithium batteries, the CNFs were prepared by electrospinning of PVA and PVA–CNT blend, which was exposed to iodine vapor at various temperatures (60, 80, and 100°C). Iodine vapor treatment at 80°C and subsequent carbonization at 800°C provided a 29% carbon yield. The resulting CNT‐containing optimized CNFs exhibited superior flexibility, electrical conductivity (2.16 S/cm), and handleability, making them a promising, binder‐free environmentally friendly carbon source for lithium‐ion batteries with high capacity (672 mAh/g at 50 mA/g). The study clearly showed that PVA might be an alternative precursor for the production of carbon micro‐ and nanofibers.Highlights Anodic performance of PVA‐based carbon nanofibers was analyzed. PVA precursor offers economic and environmental option for binder‐free electrodes. PVA–CNT composite nanofibers with optimized iodination and carbonization time identified as a promising high carbon yield carbon source for lithium‐ion batteries. CNT‐containing optimized carbon nanofibers exhibited superior flexibility and electrical conductivity (2.16 S/cm). Freestanding fiber anodes exhibited a higher capacity of 672 mAh/g, at 50 mA/g compared to conventional graphite anode (372 mAh/g).

Novel Aphid-Repellent Fiber Mats Based on Poly(lactic acid)-Containing Ionic Liquids.

To protect crops as well as human and animal health, the development of novel repellents based on biopolymers is critical for a growing world population. Here, novel aphid-repellent electrospun mats containing epoxidized ionic liquids (ILs) covalently bonded to the carboxyl or hydroxyl groups of poly(lactic acid) (PLA) were designed to produce nonwoven mats. First, di-, tri-, and tetra-epoxidized imidazolium ILs were synthesized and incorporated in different weight fractions (3, 5, and 10 wt %) into the PLA solution. Then, the effect of ILs' microstructure, thermal properties, mechanical performance, and hydrophobic behavior were investigated. It was found that the incorporation of ILs resulted in a reduction of the fiber diameters while the mechanical properties of the mats, i.e., the three-dimensional fibrous porous structure, were maintained. Finally, the effect of these three ILs against the pea aphid Acyrthosiphon pisum (Harris) was evaluated for the first time, showing an attractive effect for the diepoxidized IL and a repellent effect for the tri- and tetra-epoxidized ILs. By exploiting the chemical nature of ILs, an environmentally friendly strategy can be developed to limit the need for chemical pesticides and petroleum-based polymers.