Showing papers on "Fiber published in 2021"

A review on natural fibers for development of eco-friendly bio-composite: characteristics, and utilizations

Abstract: Understanding the basic properties of natural fibers is important to determine the optimal intended uses for instance as high-quality bio-composite raw material. This review describes the characteristics, and potential uses of some natural fibers in order to improve their sustainability and economic values. The natural fibers have low density and high strength to weight ratio and reduction make them potential as light weight composite and reinforcement materials. The microstructure and chemical compositions of fibers affect the mechanical properties with the fiber cross-sectional area is the most variable influencing the fiber strength. Natural fibers are easy to absorb water due to the presence of hemicellulose that give hydrophilic properties make them less compatible in the interaction with matrix with hydrophobicity properties. Higher cellulose content and crystallinity tend to result better strength properties of fiber while lignin is since versa. Besides that, fiber anatomical characteristics vary between different and same species that affect on the density and mechanical properties. The other factors namely environmental conditions, method of transportation, storage time and conditions, and fiber extraction affect the size and quality of the natural fibers.

Flexible and Stretchable Fiber-Shaped Triboelectric Nanogenerators for Biomechanical Monitoring and Human-Interactive Sensing

Abstract: Wearable, flexible, and even stretchable tactile sensors, such as various types of electronic skin, have attracted extensive attention, which can adapt to complex and irregular surfaces, maximize the matching of wearable devices, and conformally apply onto human organs. However, it is a great challenge to simultaneously achieve breathability, permeability, and comfortability for their development. Herein, mitigating the problem by miniaturizing and integrating the sensors is tried. Highly flexible and stretchable coaxial structure fiber-shaped triboelectric nanogenerators (F-TENGs) with a diameter of 0.63 mm are created by orderly depositing conductive material of silver nanowires/carbon nanotubes and encapsulated polydimethylsiloxane onto the stretchable spandex fiber. As a self-powered multifunctional sensor, the resulting composite fiber can convert mechanical stimuli into electrical signals without affecting the normal human body. Moreover, the F-TENGs can be easily integrated into traditional textiles to form tactile sensor arrays. Through the tactile sensor arrays, the real-time tactile trajectory and pressure distribution can be precisely mapped. This work may provide a new method to fabricate fiber-based pressure sensors with high sensitivity and stretchability, which have great application prospects in personal healthcare monitoring and human–machine interactions.

Fiber-based thermoelectrics for solid, portable, and wearable electronics

Abstract: With the growing demand for solid, portable, and wearable electronics, exploring recyclable and stable charging and cooling techniques is of significance. Fiber-based thermoelectrics, enabling sustainable power generation driven by the temperature difference or refrigeration without noise and freon, exhibit great potentials for applying in advanced electronics. In this work, we review significant advances in fiber-based thermoelectrics, including inorganic fibers, organic fibers, inorganic/organic hybrid fibers, and fiber-based fabrics and devices. Fundamentals, synthesis, characterizations, property evaluation, and applications of thermoelectric fibers are comprehensively discussed with carefully selected cases, and corresponding thermoelectric devices based on these advanced fibers are introduced for both power generation and refrigeration. Further, we point out the challenges and future directions toward developments of fiber-based thermoelectrics.

High Concentration of Ti3C2Tx MXene in Organic Solvent.

Abstract: MXenes are currently one of the most widely studied two-dimensional materials due to their properties. However, obtaining highly dispersed MXene materials in organic solvent remains a significant challenge for current research. Here, we have developed a method called the tuned microenvironment method (TMM) to prepare a highly concentrated Ti3C2Tx organic solvent dispersion by tuning the microenvironment of Ti3C2Tx. The as-proposed TMM is a simple and efficient approach, as Ti3C2Tx can be dispersed in N,N-dimethylformamide and other solvents by stirring and shaking for a short time, without the need for a sonication step. The delaminated single-layer MXene yield can reach 90% or greater, and a large-scale synthesis has also been demonstrated with TMM by delaminating 30 g of multilayer Ti3C2Tx raw powder in a one-pot synthesis. The synthesized Ti3C2Tx nanosheets dispersed in an organic solvent possess a clean surface, uniform thickness, and large size. The Ti3C2Tx dispersed in an organic solvent exhibits excellent oxidation resistance even under aerobic conditions at room temperature. Through the experimental investigation, the successful preparation of a highly concentrated Ti3C2Tx organic solvent dispersion via TMM can be attributed to the following factors: (1) the intercalation of the cation can lead to the change in the hydrophobicity and surface functionalization of the material; (2) proper solvent properties are required in order to disperse MXene nanosheets well. To demonstrate the applicability of the highly concentrated Ti3C2Tx organic solvent dispersion, a composite fiber with excellent electrical conductivity is prepared via the wet-spinning of a Ti3C2Tx (dispersed in DMF) and polyacrylonitrile mixture. Finally, various types of MXenes, such as Nb2CTx, Nb4C3Tx, and Mo2Ti2C3Tx, can also be prepared as highly concentrated MXene organic solvent dispersions via TMM, which proves the universality of this method. Thus, it is expected that this work demonstrates promising potential in the research of the MXene material family.

Cellulose-Based Hybrid Structural Material for Radiative Cooling

Abstract: Structural materials with excellent mechanical properties are vitally important for architectural application. However, the traditional structural materials with complex manufacturing processes cannot effectively regulate heat flow, causing a large impact on global energy consumption. Here, we processed a high-performance and inexpensive cooling structural material by bottom-up assembling delignified biomass cellulose fiber and inorganic microspheres into a 3D network bulk followed by a hot-pressing process; we constructed a cooling lignocellulosic bulk that exhibits strong mechanical strength more than eight times that of the pure wood fiber bulk and greater specific strength than the majority of structural materials. The cellulose acts as a photonic solar reflector and thermal emitter, enabling a material that can accomplish 24-h continuous cooling with an average dT of 6 and 8 °C during day and night, respectively. Combined with excellent fire-retardant and outdoor antibacterial performance, it will pave the way for the design of high-performance cooling structural materials.

Carbon hollow fiber membranes for a molecular sieve with precise-cutoff ultramicropores for superior hydrogen separation.

Abstract: Carbon molecular sieve (CMS) membranes with rigid and uniform pore structures are ideal candidates for high temperature- and pressure-demanded separations, such as hydrogen purification from the steam methane reforming process. Here, we report a facile and scalable method for the fabrication of cellulose-based asymmetric carbon hollow fiber membranes (CHFMs) with ultramicropores of 3–4 A for superior H2 separation. The membrane fabrication process does not require complex pretreatments to avoid pore collapse before the carbonization of cellulose precursors. A H2/CO2 selectivity of 83.9 at 130 °C (H2/N2 selectivity of >800, H2/CH4 selectivity of >5700) demonstrates that the membrane provides a precise cutoff to discriminate between small gas molecules (H2) and larger gas molecules. In addition, the membrane exhibits superior mixed gas separation performances combined with water vapor- and high pressure-resistant stability. The present approach for the fabrication of high-performance CMS membranes derived from cellulose precursors opens a new avenue for H2-related separations. Energy-efficient hydrogen purification technologies are needed for the hydrogen economy. Here the authors report facile and scalable fabrication of asymmetric carbon molecular sieve membranes for the separation of hydrogen and carbon dioxide.

Thermogravimetric Analysis Properties of Cellulosic Natural Fiber Polymer Composites: A Review on Influence of Chemical Treatments.

Abstract: Natural fiber such as bamboo fiber, oil palm empty fruit bunch (OPEFB) fiber, kenaf fiber, and sugar palm fiber-reinforced polymer composites are being increasingly developed for lightweight structures with high specific strength in the automotive, marine, aerospace, and construction industries with significant economic benefits, sustainability, and environmental benefits. The plant-based natural fibers are hydrophilic, which is incompatible with hydrophobic polymer matrices. This leads to a reduction of their interfacial bonding and to the poor thermal stability performance of the resulting fiber-reinforced polymer composite. Based on the literature, the effect of chemical treatment of natural fiber-reinforced polymer composites had significantly influenced the thermogravimetric analysis (TGA) together with the thermal stability performance of the composite structure. In this review, the effect of chemical treatments used on cellulose natural fiber-reinforced thermoplastic and thermosetting polymer composites has been reviewed. From the present review, the TGA data are useful as guidance in determining the purity and composition of the composites’ structures, drying, and the ignition temperatures of materials. Knowing the stability temperatures of compounds based on their weight, changes in the temperature dependence is another factor to consider regarding the effectiveness of chemical treatments for the purpose of synergizing the chemical bonding between the natural fiber with polymer matrix or with the synthetic fibers.

A review on recycling and reuse methods for carbon fiber/glass fiber composites waste from wind turbine blades

Abstract: The development of novel strategies for recycling and reusing fiber composites is driven by various environmental and economic factors. Recycling materials mean that materials are processed with feasible processing methods or environment-friendly methods without deterioration of mechanical or physical performance enabling their reuse. Recycling end-of-life (EOL) waste of wind turbine (WT) blade composites is a critical challenge for renewable energy sector. This paper reviews various recycling methods (mechanical, thermal, chemical, and hybrid) and reuse of reclaimed fiber composites of carbon and glass fibers. Physical, mechanical, and chemical properties of recovered fibers and new composites (made of recovered fibers) have been discussed in detail. This paper aims to find out the optimum recycling process from existing recycling methods to recycle EOL waste of WT blades. Glass fibers (GFs) and carbon fibers (CFs) are energy-intensive to manufacture, which means these have high recycling capability in terms of the environment as well as an economic perspective. Challenges in the recycling of fibers have been identified from the available literature; future research possibilities with promising values of recovered fibers to reuse in some high-value structural applications have been highlighted.

The Interfacial Shear Strength of Carbon Nanotube Sheet Modified Carbon Fiber Composites

Abstract: Carbon fiber reinforced polymer composites have low density and high tensile strengths. However, their compressive strengths are much lower than their corresponding tensile strengths due to fiber micro-buckling and interface failure between fiber and matrix. To address this issue, we report a method for fabricating carbon nanotube (CNT) sheet scrolled carbon fibers or fiber tows to improve the interfacial shear strengths. A CNT sheet is drawn from a drawable carbon nanotube forest grown on a silicon substrate, it is used to wrap around individual carbon fibers. The CNT wrapped carbon fiber is subsequently impregnated into a polymer to form a composite. Scanning electron micrograph shows that the wettability of CNT wrapped carbon fiber composite increases drastically in comparison with the composite without CNT, indicating significantly increased bonding between carbon fiber and polymer due to the addition of aligned CNT at the interphase. Fiber push-out and push-in nanoindentation characterization indicates increased interfacial shear strengths, consistently at over 80% with the use of wrapped aligned CNT sheet. The results from scrolling CNT sheet around individual carbon fibers to enhance compressive strengths indicate the potential performance enhancement of composites when this approach is scaled up.

Influence of Stacking Sequence and Fiber Content on the Mechanical Properties of Natural and Synthetic Fibers Reinforced Penta-Layered Hybrid Composites

Abstract: The objective of this work is to find the influence of fiber content, stacking pattern, and their sequence on the mechanical properties of hybrid composites Hybrid composites in four varieties wit

Developing a hybrid model of salp swarm algorithm-based support vector machine to predict the strength of fiber-reinforced cemented paste backfill

Abstract: To test the impact of different mixture ratios on backfilling strength in Fankou lead–zinc mine, various mixture ratio designs have been conducted. Meanwhile, to improve the strength of ultra-fine tailings-based cement paste backfill (CPB), two kinds of fibers were utilized in this study, namely polypropylene (PP) fibers and straw fibers. To achieve these, a total of 144 CPB backfilling scenarios with different combinations of influenced factors were tested by uniaxial compressive tests. The test results indicated that polypropylene fibers improve the strength of CPB, while in some scenarios the addition of straw fibers decreases the strength of CPB. In this research, the support vector machine (SVM) technique coupled with three heuristic algorithms, namely genetic algorithms, particle swarm optimization and salp swarm algorithm (SSA), was developed to predict the strength of fiber-reinforced CPB. Also, the optimal performance of metaheuristic algorithms was compared with one fundamental search method, i.e., grid search (GS). The overall performance of four optimal algorithms was calculated by the ranking system. It can be found that these four approaches all presented satisfactory predictive capability. But the metaheuristic algorithms can capture better hyper-parameters for SVM prediction models compared with GS-SVM method. The robustness and generalization of SSA-SVM methods were the most prominent with the R2 values of 0.9245 and 0.9475 for training sets and testing sets. Therefore, SSA-SVM will be recommended to model the complexity of interactions for fiber-reinforced CPB and predict fiber-reinforced CPB strength.

Constructing Mesoporous Adsorption Channels and MOF-Polymer Interfaces in Electrospun Composite Fibers for Effective Removal of Emerging Organic Contaminants.

Abstract: Recently, metal-organic framework (MOF)-based electrospun fibers have attracted considerable attention as adsorbents for organic contaminant removal from water. To prepare these fibers, two common strategies including blending electrospinning and surface coating are employed. However, fibers obtained from the two strategies still have some disadvantages, such as adsorption site blockage and unstable loading. Here, we constructed interconnected mesopores in the electrospun zeolitic imidazolate framework-8 (ZIF-8)/polyacrylonitrile (PAN) fibers with the assistance of poly(vinylpyrrolidone) to expose more adsorption sites of ZIF-8 and make ZIF-8 more stable. Moreover, the mesopores could also enhance the diffusion of contaminant molecules and create MOF-polymer interfaces in the fiber, which improve the adsorption rate and adsorption capacity, respectively. The obtained fibers were used to adsorb antibiotic tetracycline from water. Benefiting from the mesoporous adsorption channels and the MOF-polymer interface, porous ZIF-8/PAN fibers showed faster adsorption kinetics than ZIF-8/PAN blending fibers and larger adsorption capacity than ZIF-8-coated PAN fibers and ZIF-8/PAN blending fibers. The maximum adsorption capacity of porous ZIF-8/PAN fibers was 885.24 mg/g, which is close to that of pure ZIF-8. After 10 adsorption-desorption cycles, the removal efficiency was still above 97%. In addition, porous ZIF-8/PAN fibers could act as the membrane adsorbents to dynamically separate tetracycline with a treated capacity of 9.93 × 103 bed volumes. These results demonstrate that our prepared porous ZIF-8/PAN fibers have great potential in antibiotic drug removal.

Polyimide Aerogel Fibers with Superior Flame Resistance, Strength, Hydrophobicity, and Flexibility Made via a Universal Sol-Gel Confined Transition Strategy.

Abstract: Aerogel fibers with ultrahigh porosity, large specific surface area, and ultralow density have shown increasing interest due to being considered as the next generation thermal insulation fibers. However, it is still a great challenge to fabricate arbitrary aerogel fibers via the traditional wet-spinning approach due to the obvious conflict between the static sol-gel transition of the aerogel bulks and the dynamic wet-spinning process of aerogel fibers. Herein, a sol-gel confined transition (SGCT) strategy was developed for fabricating various mesoporous aerogel fibers, in which the aerogel precursor solution was first driven by the surface tension into the capillary tubes, then the gel fibers were easily formed in the confined space after static sol-gel process, and finally the mesoporous aerogel fibers were obtained via the supercritical CO2 drying process. As a typical case, the polyimide (PI) aerogel fiber prepared via the SGCT approach has exhibited a large specific surface area (up to 364 m2/g), outstanding mechanical property (with elastic modulus of 123 MPa), superior hydrophobicity (with contact angle of 153°), and excellent flexibility (with curvature radius of 200 μm). Therefore, the aerogel woven fabric made from PI aerogel fibers has possessed an excellent thermal insulation performance in a wide temperature window, even under the harsh environment. Besides, arbitrary kinds of aerogel fibers, including organic aerogel fibers, inorganic aerogel fibers, and organic-inorganic hybrid aerogel fibers, have been fabricated successfully, suggesting the universality of the SGCT strategy, which not only provides a way for developing aerogel fibers with different components but also plays an irreplaceable role in promoting the upgrading of the fiber fields.

Bio-Inspired Lotus-Fiber-like Spiral Hydrogel Bacterial Cellulose Fibers

Abstract: Hydrogel materials with high water content and good biocompatibility are drawing more and more attention now, especially for biomedical use. However, it still remains a challenge to construct hydrogel fibers with enough strength and toughness for practical applications. Herein, we report a bio-inspired lotus-fiber-mimetic spiral structure hydrogel bacterial cellulose fiber with high strength, high toughness, high stretchability, and energy dissipation, named biomimetic hydrogel fiber (BHF). The spiral-like structure endows BHF with excellent stretchability through plastic deformation and local failure, assisted by the breaking-reforming nature of the hydrogen bonding network among cellulose nanofibers. With the high strength, high stretchability, high energy dissipation, high hydrophilicity, porous structure, and excellent biocompatibility, BHF is a promising hydrogel fiber for biomedicine. The outstanding stretchability and energy dissipation of BHF allow it to absorb energy from the tissue deformation around a wound and effectively protect the wound from rupture, which makes BHF an ideal surgical suture.

Photonic smart bandage for wound healing assessment

Abstract: Chronic wounds affect around 2% of the world population with an annual multi-billion dollar cost to the healthcare system. This background pushes the development of new therapies and procedures for wound healing and its assessment. Among them, the potential of hydrogen (pH) assessment is an important indicator of the wound healing stage and condition. This paper presents the development of the first optical fiber-embedded smart wound dressing for pH assessment. An intrinsically pH-sensitive optical fiber is fabricated using a polydimethylsiloxane (PDMS) precursor doped with rhodamine B dye. Raman and Fourier transform infrared (FTIR) spectroscopies are performed in order to verify the presence of rhodamine B and PDMS in the fiber samples. Then, the fiber is embedded in gauze fabric and hydrocolloid wound dressing. In addition, such low Young’s modulus of PDMS fiber enables its use as a highly sensitive pressure sensor, where the results show that the fiber-embedded bandage can measure pressures as low as 0.1 kPa with a high linearity in the range of 0 to 0.3 kPa. The smart bandage is subjected to different pH, which resulted in a wavelength shift of 0.67 nm/pH when the absorption peak at 515 nm was analyzed. Furthermore, pH increase leads to linear decrease of the transmitted optical power (R2 of 0.998), with rise and fall times below 20 s and 30 s, respectively. Therefore, the proposed optical fiber-embedded smart bandage enables the simultaneous assessment of pressure and pH on the wound region.

Nano-Fe3O4/bamboo bundles/phenolic resin oriented recombination ternary composite with enhanced multiple functions

Abstract: High-performance bamboo-/wood-based structural or building materials have attracted more and more attention as a kind of renewable carbon cycle materials. However, biomass materials are prone to mildew, poor surface hydrophobicity and bad dimensional stability when used outdoors, which seriously restricts their applications. In this work, nano-Fe3O4/bamboo bundles/phenolic resin oriented recombination ternary composite boards are successfully fabricated by directional recombination and hot-pressing of nano-Fe3O4 decorated bamboo bundles. Through the combination of iron/alkali liquid step-by-step impregnation and nanocrystalline in-situ crystallization, nano-Fe3O4 particles are pre-modified on bamboo bundle surface with characteristics of directional arrangement along the fiber direction. The obtained samples which are named as T1, T2 and T3 with increasing nano-Fe3O4 loading content, exhibit enhanced hydrophobicity along with varied physico-mechanical properties. Among them, T2 possesses the best compressive properties, dimensional stability, and mildew resistance, being attributed to the role from nano-Fe3O4 in bridging and enhancing the interactions between bamboo bundles and phenolic resin through ion-dipole interaction between iron atoms and electron-rich oxygen atoms. Furthermore, on the basis of maintaining the unique pore-line staggered structural characteristics of bamboo, the construction of micro continuous equivalent circuit network of the ternary composites is realized, endowing their efficient electromagnetic dissipation capacity. Our work provides systematic experimental and theoretical support for the application of high-performance outdoor recombinant bamboo board in specific scenes.