Microfiber Composite Research Articles

Microstructure and Performance Study of PETMF/WPU Composites Prepared by Water‐Soluble Method

AbstractCurrently, waterborne polyurethane (WPU)/polyethylene terephthalate (PET) microfiber composites are typically produced using PET/alkali‐soluble polyethylene terebenzoate (COPET) as the island fiber. This involves dissolving COPET with alkali (NaOH) after WPU impregnation, resulting in significant alkali‐containing wastewater and weakening the composites’ strength due to the strong alkali treatment. To address these issues, this study employs PET/PVA island fiber as the raw material, comprising 36 islands. PET serves as the water‐insoluble component, while PVA is the water‐soluble component, with a fiber ratio of 70 % PET to 30 % PVA. The PET/WPU microfiber composites are prepared via a water‐soluble method following WPU impregnation. The study examines the impact of water deweighting time, WPU impregnation amount, and water washing times on the deweighting rate of the composites. Scanning electron microscopy (SEM) characterized their microstructure. Findings indicate that with 30 % WPU impregnation, 80 °C water temperature, 40‐minute deweighting time, and three water washes, the deweighting rate of PET/WPU microfiber composites reaches 29.08 %, close to 30 %. SEM analysis confirms that PET/PVA island fiber composites were fully converted into PET/WPU microfiber composites, with most PET/PVA island fibers completely opened. The water‐soluble method presents a novel deweighting technology with significant environmental benefits and considerable research potential.

Active Pointing Compensation of a HTS Multibeam Antenna

Active pointing compensation of a High Throughput Satellite (HTS) multibeam antenna via microfiber composites (MFCs) is studied in this paper. Electrical-mechanical coupling analysis of MFCs is conducted to quantitatively determine driving forces and moments of MFCs attached on a carbon fiber reinforced composite (CFRP) laminate, and a positive correlation relationship is observed for driving ability versus thickness of the laminate. By different driving strategies, MFCs could act in bending mode and torsioning mode for structural deformation control, and driving efficiency of the MFCs on a multibeam antenna is studied. Thermal distortion of the antenna under a typical in orbit thermal distribution causes the reflector to rotate about y axis with an pointing error of 0.005°, active compensation is conducted, and the final compensation results show that with an optimal voltage of 432 V, pointing error of the antenna is greatly compensated, and the depointing angle is corrected to be 0.00004°.

A supply-chain perspective on producing and upscaling bioplastic from cultivated brown seaweed

Plastic pollution is an environmental emergency and finding sustainable alternatives to traditional plastics has become a pressing need. Seaweed-based bioplastic has emerged as a promising solution, as it is biodegradable and made from renewable biomass, while seaweed cultivation itself provides various environmental benefits. However, the feasibility of implementing a brown seaweed-based bioplastic supply chain in a realistic setting remains unclear, as previous research focused either on single processing steps or on virtual supply chains aggregating data from different studies. This study describes a case study for seaweed-based bioplastic within the PlastiSea research project: from seaweed cultivation to biomass processing and bioplastic and composite material development at the lab and pilot scale, thus providing insights into its feasibility. Adopting a multidisciplinary approach, the study employs multiple methods to characterize each stage in the supply chain and provides an overall life cycle assessment (LCA) as well as lessons learned throughout the process. The analysis showed potential for producing and utilizing multiple co-products from the same seaweed source, including biopolymer extracts with varying degrees of refinement for use in low-cost (bioplastic films) and high-cost (microfiber composites) applications. The use of residual biomass as a source of alginates for producing bioplastics offers a low-cost and sustainable biomass supply currently not competing with other markets. The LCA results indicate the potential for reducing the environmental impact of seaweed-based bioplastic production through upscaling and increasing process efficiency.

Enhancement of integrated nano-sensor performance comprised of electrospun PANI/carbonaceous material fibers for phenolic detection in aqueous solutions

The detection of trace levels of organic residue in water samples is a key health issue. This manuscript describes the fabrication of integrated nano-sensors composed of electrospun microfibers consisting of a nanocomposite of carbonaceous materials (CNMs) containing polyaniline (PANI) and polycaprolactone (PCL) for phenolic detection in aqueous solutions. The morphology of the resulting microfiber composite was characterized by scanning electron microscopy. It revealed elongated fibers with a highly interconnected web-like pattern in the presence of reduced graphene oxide (rGO). Shorter microfibers were observed in the composite filled with multi-walled carbon nanotubes (MWCNTs), whereas large agglomerates were formed upon the incorporation of single-walled CNTs (SWCNTs) and graphene 300 (G300). Comparative analysis showed that the PANI/CNM sensors exhibited the best electrochemical properties, in particular in the presence of rGO and MWCNTs, where greater electrical conductivity was achieved, i.e., 4.33 × 10−3 and 7.22 × 10−4 S/cm, respectively, as compared to the PANI-PCL sensor (3.79 × 10−4 S/cm). All the PANI/CNM sensors exhibited high sensitivity. Notably, PANI/rGO was found to have a detection limit of 8.34 × 10−3 µM for aminophenol. All the sensors exhibited good selectivity in the presence of interference to detecting phenolic compounds in aqueous solutions, thus confirming their value for industrial applications.

Self‐Powered Piezoelectric Actuation Systems Based on Triboelectric Nanogenerator

AbstractSustainable power supply via triboelectric nanogenerator (TENG) is attractive for self‐powered actuation systems in the era of the Internet of Things (IoTs). Herein, a low‐power actuation scheme enabled by the multilayered TENG for piezoelectric actuators, including the stack, unimorph, and micro‐fiber composite (MFC) actuator, is reported. The working principles of TENG‐powered piezoelectric actuators and their displacement characteristics in direct current (DC) and alternating current (AC) modes are theoretically investigated. Compared with conventional high‐voltage power sources, the multilayered TENG delivers a maximum power of only 10.17 mW, providing a low‐power alternative for piezoelectric actuator with self‐powered capability and operational safety. Meanwhile, the hysteresis of the stack actuator that is critical in precise positioning control is reduced by 58.1%. A precise positioning system is demonstrated by utilizing the TENG‐powered stack actuator as an object stage for microscope focusing applications. The feasibility of vibration control with a 76.7% reduction in vibration amplitude is also verified via two TENG‐powered MFC actuators. A rectifying control circuit comprising the rectifier and gas discharging tube is established to implement AC–DC conversion and discharging control, achieving a larger displacement of the unimorph actuator. The TENG‐powered piezoelectric micropump demonstrates its potential application in liquid transport through straightforward operation.

AC conductivity, dielectric and thermal properties of three-phase hybrid composite: PVA/Bi2O3/cotton microfiber composite

The impact of bismuth (III) oxide (Bi2O3) on the characteristics of the cellulose/polyvinyl alcohol (PVA) blend was reported for a high weight ratio of the oxide (15wt%). Composite samples were made with 15wt% oxide and 2:1 weight ratio of PVA to cellulose using a hot hydraulic press technique (5 MPa and 175 °C), which led to samples in the form of a disk. The thermal stability of the composite was illustrated using the thermal gravitational analysis (TGS) at a heating rate of 10 °C min−1 in N2 environment. The results show that the thermal stability of the composite sample was greater than that of the blended sample in the high-temperature region. The blend and composite samples exhibited two weight-loss stages throughout the thermal decomposition process. These two stages correspond to the slow decomposition (200 to 400 °C) and fast decomposition stages (400 to 450 °C for blend and from 430 to 460 °C for composite). Only 5% mass loss for both samples was detected due to heating from 50 °C to 200 °C. Dielectric spectroscopy (from 100 Hz to 1 MHz) was used to investigate the effects of Bi2O3 on the relaxation and conduction mechanisms of the composite samples at different temperatures. Dielectric permittivity, AC conductivity, electrical modulus, and complex impedance were investigated. Jonscher’s equation was applied to the blend and composite samples. The modified Jonscher’s equation fit well at low temperatures. As the temperature increases, the deviation from the normal Jonscher equation decreases. The activation energies of the blend and composite were calculated by determining the bulk resistance (RB) from the Nyquist plots. The activation energy of the blend was increased by adding the filler (Bi2O3).

The Study of the Influence of Temperature and Low Frequency on the Performance of the Laminated MFC Piezoelectric Energy Harvester

MFC (Microfiber composite) piezoelectric transducers are one of the smart composite materials used among others in alternative energy sources and autonomous wireless sensors which exploit vibrational energy. This work presents the theoretical and experimental investigations of the integration of MFC piezoelectric transducers on epoxy glass fiber composite material and explores the capacity of power generation based on a variety of ambient temperatures and frequencies. The study examined the use of ambient vibrational energy to power small electronic devices of wireless sensor networks which eliminates the need for external power, periodic battery replacement costs, and chemical waste from conventional batteries. The test was conducted using a laboratory stand equipped with a thermal chamber and an Instron ElectroPulse waveform generator which induces a concentric cyclic load to the laminated beam. Laminated MFC was loaded with a low–frequency range, controlled displacement under different moderate temperatures. The test was conducted at temperatures ranging from 25 to 60 degrees Celsius and at frequencies ranging from 5 to 25 Hz. The results show that the voltage generated by the transducer is highly affected by both temperature and frequency of excitation.

High‐Performance, Superhydrophobic, and Wearable Strain Sensor for Amphibious Human Motion Detection

AbstractWearable strain sensors with water repellency can enable the monitoring of human health and body motions when in contact with water; however, realization of such sensors with both high sensitivity and dynamic wetting behaviors simultaneously in air and underwater environment is a challenging task. Herein, a superhydrophobic, breathable, and wearable microfiber composite (SBWMC) strain sensor is fabricated using a stearic acid functionalized multi‐walled carbon nanotubes/TiO2 modified textile. The resultant network of hierarchical micro/nano structure endows the SBWMC surface with excellent conductivity and water damage prevention, and it maintains superhydrophobicity after mechanical abrasion, illumination, and water soaking. More importantly, the SBWMC strain sensor simultaneously achieves the wide sensing ranges (strain over 100%) and superior sensitivity (gauge factor of 461.5) in air, and it can efficiently monitor real‐time bending of human joints in air. Compared to traditional sensors, this SBWMC strain sensor also exhibits superior sensitivity in underwater environment, even comparable to that in air. Undoubtedly, such smart sensor offers broad application prospects in next generation of wearable electronic devices in extremely humid environments.

Comparing adsorption performance of microfibers and nanofibers with commercial molecularly imprinted polymers and restricted access media for extraction of bisphenols from milk coupled with liquid chromatography

Advanced solid phase extraction (SPE) fibrous sorbents including polyethylene, polypropylene poly (hydroxybutyrate), and polyamide 6 nanofibers, polycaprolactone microfibers/nanofibers, polycaprolactone microfibers/polyvinylidene difluoride nanofibers, and poly (hydroxybutyrate) microfibers/polypropylene microfibers composites, as well as commercial molecularly imprinted polymers and restricted access media sorbent were compared in terms of bisphenols extraction from milk and their clean-up efficiency. Three on-line SPE-HPLC methods were completely validated for the extraction and detection of bisphenols A, AF, C, A diglycidyl ether, and F diglycidyl ether in bovine milk. Polycaprolactone composite nanofibers compared favorably to restricted access media, enabled excellent clean-up of bisphenols from the proteinaceous matrix, and yielded recoveries 98.0–124.5% and 93.0–115.0%, respectively, with RSD less than 10%. Total analysis time including on-line SPE step lasted only 12 min, which represents a significant reduction in time compared with previously reported as well as official European Union and AOAC methods defined for the determination of bisphenols in various matrices.

Porous cage-like microfiber of fly ash magnetic powder (CMS)/polyaniline (PANI) composites with absorption properties

In order to recycling adsorbent of wastewater, magnetic adsorbents with recycling properties were prepared by fly ash magnetic powder (CMS)-doped polyaniline microfiber composites (CMS/PANI microfiber). The cheap fly ash magnetic powder is obtained from industrial solid waste fly ash. XRD patterns of CMS/PANI microfiber shows that the peaks at 30° are corresponding to the magnetite in CMS. SEM images shows that CMS/PANI fibrous winding structures forming a porous cage, where microfiber have the diameter of 60 nm and the length of 2–3 um. EDS spectra indicated that the magnetic dots monodispersed on the surface of every root of microfiber. BET surface areas of PANI microfiber and CMS/PANI microfiber are 36.42 m2 g−1 and 25.75 m2 g−1, respectively. The different wastewater samples has been used including congo red(CR), methyl orange(MO) and halogenated element ions solutions. The maximum adsorption amounts of CR and MO were 324.68 mg g−1 and 212.3 mg g−1, respectively. Interestingly, the CMS/PANI nanofibre material still adsorbs very well to other ionic wastewaters. The magnetic adsorbent achieves a sorption rate of 70% for Ca2+ containing wastewater under certain conditions. The magnetic adsorbent exhibited 48% adsorption of Cl− and over 90% adsorption of F−, Br− and I−. After six cycles of magnetic separation, the adsorption rate was still above 96%. The adsorption curves and equation fits show that the adsorption process is consistent with the langmuir isotherm model and the quasi-secondary kinetic model.

The double-coating structure of C/Cu/NiP microfiber composites for enhanced microwave absorption properties

The double-coating structure of C/Cu/NiP microfiber composites for enhanced microwave absorption properties

A programmable macro-fiber-composite meta-ring with digital shunting circuits

Representing a typical class of active metamaterials with unprecedented adaptiveness, piezoelectric metamaterials have received a lot of research efforts, but which are mostly focused on beam- and plate-types. In this research, we propose a piezoelectric meta-ring shunted with digital high-order resonant circuits, where the micro-fiber-composite (MFC) are used as the electrical-mechanical transducers. Due to the programmability of digital circuits, the bandgap behavior of the meta-ring is highly adaptive. The analytical dispersion relation of meta-ring cells is achieved with the transfer matrix method. To study dynamic response of the finite meta-ring system, we derive the six-order electrical-mechanical coupling equation, and also establish its discretized form using the assumed-mode expansion method. The finite-element simulations are performed to verify this analytical model. By homogenizing the meta-ring under the long-wavelength assumption, a simplified model is attained, so as to provide a convenient means to design the bandgaps and perform stability analysis. For the sake of implementing high-order local-resonance bandgaps, we investigate two manners based on the pole-zero placement to design digital circuits. The bandgap boundaries under these two scenarios are analytically identified. Additionally, the bandgap performance of the meta-ring is simulated, followed by a comprehensive investigation of the impacts of electrical parameters, including the gain, damping and poles-zeros. For the inversely designed digital circuits, the bifurcation phenomenon of poles of the electrical admittance is uncovered, which impacts the stability of circuits. Lastly, we build an experimental set-up of the digital MFC meta-ring. Its programmable and high-order local-resonance bandgap performance is validated experimentally.

Cellulosic Microfiber Extraction from Ecofriendly Bahunia Racemosa and Its Characterization

ABSTRACT Recent demand of eco-friendly advanced materials for automotive components motivated to develop natural fiber-reinforced composites due to their extraordinary properties with minimum weight at low cost. The reinforcement of microcellulosic extracted from lignocellulosic materials can enhance the mechanical properties with astonishing the biodegradability quality in the polymer-based composites. Bahunia racemosa (BR) fibers were chosen to extract cellulose microfibers through chemo-mechanical method and the chemical compositions at different stages are determined by using ASTM standards. The average diameter of the extracted cellulose micro Bahunia racemosa fibers (CMBRF) found as 10 μm. The microfiber composites are fabricated at different weight fractions such as 20, 30, 40 and 50 by compression molding method. Surface properties of the produced fibers and fabricated composite structures are analyzed through microscopic techniques. The influence of reinforcement effect on the mechanical properties of fabricated composite structures is analyzed through standard testing methods. The composites reinforced with 40 wt% of cellulose microfibers exhibited highest enhancement about the tensile strength and young modulus of 80.25 and 40%, respectively. The proposed composites can be used to make various low cost, light weight composite materials for industrial and construction industries.

Electrical current visualization sensor based on magneto-electrochromic effect

Electrical safety is a major threat to public safety worldwide, with fires and explosions causing damage to property and loss of life. Detection and monitoring of the occurrence of destructive current spikes can provide valuable insights into system health and inform preventative maintenance. Current sensors based on the Magnetoelectric (ME) effect have been regarded as optimal solutions because of the low power consumption and high sensitivity of ME devices compared to conventional current sensors (current transformers, Hall-effect current sensors, etc.). However, none of the conventional sensing techniques can provide ex-situ recording or a means for a human-readable signal output. Development of a current sensor that can sense, visualize, and record a current level remains a challenge. Here, we report an electric current visualization sensor that uses a coupled magnetoelectric/electrochromic effect to transform environmental current energy into electrical signals, and subsequently to a color change readily interpreted by a human observer. The current visualization sensor uses a PZT piezoelectric microfiber composite (MFC) / FeSiB alloy (Metglas) laminate combined with a Prussian blue-based electrochromic device (ECD). Such a current sensor demonstrates high efficiency self-powered current sensing and non-volatile signal recording.

Silk fibroin microfiber‐reinforced polycaprolactone composites with enhanced biodegradation and biological characteristics

There is an enormous demand for bone graft biomaterials to treat developmental and acquired bony defects arising from infections, trauma, tumor, and other conditions. Polycaprolactone (PCL) has been extensively utilized for bone tissue engineering but limited cellular interaction and tissue integration are the primary concerns. PCL-based composites with different biomaterials have been attempted to improve the mechanical and biological response. Interestingly, a few studies have tried to blend PCL with aqueous silk fibroin solution, but the structures prepared with the blend were mechanically weak due to phase mismatch. As a result, silk microparticle-based PCL composites have been prepared, but the microfibers-reinforced composites could be superior to them due to significant fiber-matrix interaction. This study aims at developing a unique composite by incorporating 100-150μm long (aspect ratio; 8:1-5:1) silk-fibroin microfibers into the PCL matrix for superior biological and mechanical properties. Two silk variants were used, that is, Bombyx mori and a wild variant, Antheraea mylitta, reported to have cell recognizable Arginine-Glycine-Aspartic acid (RGD) sequences. A.mylitta silk fibroin microfibers were produced, and composites were made with PCL for the first time. The morphological, tensile, thermal, biodegradation, and biological properties of the composites were evaluated. Importantly, we tried to optimize the silk concentration within the composite to strike a balance among the cellular response, biodegradation, and mechanical strength of the composites. The results indicate that the PCL-silk fibroin microfiber composite could be an efficient biomaterial for bone tissue engineering.

Ceramic-Based Piezoelectric Material for Energy Harvesting Using Hybrid Excitation.

This paper analyzes the energy efficiency of a Micro Fiber Composite (MFC) piezoelectric system. It is based on a smart Lead Zirconate Titanate material that consists of a monolithic PZT (piezoelectric ceramic) wafer, which is a ceramic-based piezoelectric material. An experimental test rig consisting of a wind tunnel and a developed measurement system was used to conduct the experiment. The developed test rig allowed changing the air velocity around the tested bluff body and the frequency of forced vibrations as well as recording the output voltage signal and linear acceleration of the tested object. The mechanical vibrations and the air flow were used to find the optimal performance of the piezoelectric energy harvesting system. The performance of the proposed piezoelectric wind energy harvester was tested for the same design, but of different masses. The geometry of the hybrid bluff body is a combination of cuboid and cylindrical shapes. The results of testing five bluff bodies for a range of wind tunnel air flow velocities from 4 to 15 m/s with additional vibration excitation frequencies from 0 to 10 Hz are presented. The conducted tests revealed the areas of the highest voltage output under specific excitation conditions that enable supplying low-power sensors with harvested energy.

Enhanced thermoelectric performance and mechanical strength of n-type BiTeSe materials produced via a composite strategy

Zone-melted Bi2Te2.7Se0.3 (ZM BTS) alloys are typical n-type commercial thermoelectric (TE) materials and are utilized for refrigeration and power generation near room temperature. They usually suffer from poor mechanical performance, as well as having a low figure of merit (ZT). In this work, we report an effective composite strategy to improve both the TE and mechanical performance of n-type BTS materials by incorporating carbon microfibers. The introduction of carbon microfibers in BTS effectively reduces the lattice thermal conductivity due to phonon scattering at multi-scale boundaries and due to the large interfacial thermal resistance arising from phonon mismatch between the constituent phases. Simultaneously, it also gives rise to an enhancement of the electrical conductivity, which originates from the increased carrier density without significant limitation on its weighted mobility. Consequently, a high peak ZT of 1.1 at 400 K and an average ZTave value of 0.95 are achieved in the temperature range 300 ~ 550 K, yielding a calculated efficiency of η = 9%. Moreover, the BTS/carbon microfiber composites show superior compressive strength compared to a commercial ZM BTS sample. This improved strength is highly desirable for real-world TE applications. Our results demonstrate a novel way to produce high-performance TE materials, in which interfaces with large thermal resistance are used to achieve low thermal conductivity without significantly degrading the electrical properties of the materials.

Fabrication and Characterization of Electrospun Copper Oxide-Cellulose Acetate Microfiber Composite

Antimicrobial textiles are indispensable in medical applications. Improving these textiles through the use of fiber composites in their production can further advance its applications. Electrospinning is one of the most practical and efficient methods of producing fiber composites. This research dealt with the fabrication and characterization of electrospun copper oxidecellulose acetate (CuO/CA) microfiber composite. CuO loading, electrospinning applied voltage, and flow rate were varied following a central composite design (CCD). Their effects on the antibacterial activity and morphology of the microfiber composites were determined. The presence of the functional groups of CuO in the FTIR (Fourier transform infrared) spectrum of the composite proved the embedment of CuO in the microfiber. The fiber composite inhibited the growth of Staphylococcus aureus, but no antibacterial activity was observed against Escherichia coli. Statistical analysis showed that only the CuO loading has a significant effect on the antibacterial activity against S. aureus while applied voltage and flow rate have insignificant effects. Antibacterial activity has a direct relationship with CuO loading. The increase in CuO concentration increased the fiber diameter and reduced bead formation. Fiber diameter decreases and bead formation increases at increasing applied voltage. Increasing the flow rate increases bead formation and decreases fiber diameter.

Achieving C/CuO microfiber composites with efficient microwave absorbing performance at low thickness

The carbon fibers with low density still face significant microwave absorbing application issues due to their high dielectric constant. Herein, C/Cu core–shell microfiber composites are prepared by electroless plating. The Cu coating of C/Cu core–shell microfiber composites is oxidized to CuO at 300 °C and 400 °C temperature. The morphology, microstructure, and electromagnetic characteristics of C/CuO microfiber composites were analyzed. The diameter of all the fiber composites was about 7–8 μm. The CuO coating thickness formed at 300 °C and 400 °C temperature is 30–90 nm and 300–900 nm, respectively. The annealing process tunes the electromagnetic characteristics and optimizes impedance matching. The minimum reflection loss (RL) value of C/CuO core–shell microfiber composites annealed at 300 °C temperature remarkably reaches − 46.0 dB at 1.06 mm thickness and 3.6 GHz effective absorption bandwidth (RL ≤ − 10 dB). The C/CuO microfiber composites can be the ideal absorbing materials at a lower thickness.

Optimization of microwave absorption properties of C/NiP microfiber composites

Core-shell C/NiP microfiber composites were fabricated via electroless plating in this work. Their microstructure and electromagnetic properties were adjusted by annealing treatment and different phosphorus (P) content in the NiP coating. The C/NiP microfibers composites with 6 wt % P content in the NiP coating annealed at 300 °C remarkably owns −46.7 dB strong reflection loss at 10.0 GHz with the thickness of 2.0 mm, and the effective bandwidth (RL ≤ −10 dB) reaches 8.1 GHz (3.1–11.2 GHz). This work shows that the annealing conditions and different P concentrations in the coating layers for C/NiP microfibers composites are the effective way to optimize the electromagnetic wave absorption performance.