Fiber Surface Research Articles

Regulation of fiber surface nucleation kinetics via ordered nitrogen-rich carbon dots

Three dimensional (3D) carbon-based current collectors have attracted much attentions as host for Li metal anodes (LMAs) owing to their lightweight, flexible, and wide sources etc. However, the lithiophobic nature of carbon makes it difficult to achieve low nucleation overpotential and dendrite-free Li deposition. Herein, carbon dots (CDs) with nitrogen (N)-rich were introduced to modify carbonized cotton fiber (CCF) coated by reduced graphene oxide (CD@RGCCF). Coating graphene oxide (GO) increases the active site of cotton fiber (CF), which facilitates the growth of CDs on the surface of CF fiber. The introduction of ordered structure CDs drives fast migration of Li+ in the “highway-like” channels and induces the uniform nucleation of Li in the initial stage. As a result, the obtained CD@RGCCF decreases the nucleation overpotential of Li, and achieves dendrite-free Li deposition. the CD@RGCCF|Li half cells exhibit extending cycling life over 5000 h with a voltage hysteresis of 10.5 mV at 2 mA cm−2. As coupled with the LiFePO4 (LFP), the Li@CD@RGCCF||LFP composite anode enables a high reversible specific capacity and improved cycle stability. This work provides a low-cost modification method for carbon substrate to realize dendritic-free LMAs.

Construction of PDMS@ZIF-8 composite membrane on PVDF hollow fiber inner surface for ultrafast ethanol/water separation

Construction of ultra-thin and defect-free separation membrane on inner surface of hollow fiber supports is significant but challenging for molecular separation. In this study, the highly permeable PDMS@ZIF-8/PVDF composite membranes were successfully fabricated upon the inner-surface of polyvinylidene fluoride (PVDF) hollow fiber membrane for pervaporation (PV) ethanol/water separation. The efficient preparation of hierarchical PDMS@ZIF-8/PVDF composite membranes benefited from the precise regulation of ZIF-8 layer through interfacial synthesis and sequential coating of PDMS matrix. The thickness of the PDMS layer was only 16±2 nm, which admirably eliminated the non-selective defects in ZIF-8 layer. Owning to the optimal combination of MOF layer and ultra-thin polymer layer, the as-prepared membrane exhibited the excellent ethanol flux of 1.34 kg m-2 h-1 with an ethanol concentration in permeate of 31.3 wt.% for separating 5 wt.% ethanol aqueous solution at 40°C. The separation performance of the resultant membrane was superior to that of the other ethanol selective PV membranes. These findings herein provided a new way for preparing high-performance hollow fiber composite membranes for PV separation.

The fabrication of Ni@Luffa nanocomposite as green catalyst for water pollutants Thymus vulgaris-assisted growth of nickel nanoparticles onto Luffa fibers: A robust and recyclable catalyst for the reduction of organic pollutants

A green and efficient synthetic pathway was developed to prepare nickel@Luffa nanocomposite. Thymus vulgaris extract was used to functionalize the surface of Luffa fibers with hydroxyl, carbonyl, and amide groups, which assisted in the adsorption of nickel ions. The scanning electron microscope images revealed that nickel nanoparticles grew as aggregates of semi-spherical particles and randomly dispersed on the Luffa fibers. The X-ray diffraction pattern of the nickel@Luffa nanocomposite showed the diffraction pattern of a face-centered cubic Ni crystal. XPS spectrum indicated the formation of metallic Ni at the Luffa surface. The prepared nickel@Luffa was used to catalyze the degradation of 4-nitrophenol, methyl orange, bromophenol blue and a mixture of both. The reaction rate constant for nickel@Luffa nanocomposite was calculated as 15.47×10-3 sec-1 at pH=10 and even after ten cycles its conversion was about 90%. The nickel nanoparticles could be recycled/ reused for ten catalytic cycles with adequate catalytic activity. Such synthetic pathways encourage the application of renewable natural resources to fabricate separable/recyclable heterogeneous catalyst for many important reactions. The proposed nanocomposite is industrially applicable and environmentally-benign, fulfilling the requirements for the sustainable development.

High-performance hybrid glass fibre epoxy composites reinforced with amine functionalised graphene oxide for structural applications

Glass fibre-reinforced epoxy (GFRE) composites have had limited use as structural components in industrial applications (e.g., oil and gas, aerospace and civil infrastructure). The use of nanomaterials, such as graphene, has been explored recently to enhance the mechanical and long-term properties of GFRE to realise their full potential and increase their usage. This study evaluated the tensile, creep, and fatigue behaviour of amine-functionalised graphene oxide (fGO) modified glass fibre/epoxy laminate composites. A spray coating technique was used to coat the fGO particles onto the glass fibre surface, and epoxy composite laminates were manufactured using the vacuum resin infusion method. Creep and fatigue testing were performed under a load-controlled mode in the tension direction. Adding fGO within the composites significantly improves the static, creep, and fatigue properties of the fGO-GFRE composites at both room and elevated temperatures. It is shown that adding fGO acts as a barrier to microcrack initiation and restrains the macrocrack propagation during cyclic loading under elevated temperatures in the GFRE composites. These factors, therefore, prevent the early delamination of the matrix and fibre interface during cyclic loading, which explains the fatigue life extension observed in the fGO-modified composites. With 0.05 wt% fGO, the fatigue life of the fGO-GFRE composites was extended by 8× and 30× at a maximum stress of 124–151 MPa, in a 90 °C environment compared to the control GFRE composites. While the creep life compared to the control increased by 63×, 103× and 159× with 0.25 wt%, 0.5 wt% and 1 wt% fGO, respectively. These enhancements are attributed to the large surface area, high stiffness, and functional groups present, which provide a stronger bond between the composite phases. These features help restrict the mobility of the polymer chain during the creeping load and act as barriers to fatigue crack propagation, enhancing the composite’s durability. The nanocomposites produced display attractive properties for many possible industrial applications where improved performance is needed while maintaining a minimum cost.

Multiscale analysis of hierarchical flax-epoxy biocomposites with nanostructured interphase by xyloglucan and cellulose nanocrystals

Natural biological systems feature hierarchical nanostructured architectures achieving high strength and toughness. In this work, the spontaneous adsorption of xyloglucan (XG) and cellulose nanocrystals (CNC) onto flax fabrics is considered to develop hierarchical interphases with improved interfacial adhesion in epoxy-based biocomposites. A multi-scale analysis is carried out, from the nano & micrometric scale with the characterization of fibre surface topography, work of adhesion and interfacial shear strength (IFSS) between flax fibres and epoxy resin, to the macroscopic scale with the transverse mechanical properties of biocomposites. At the fibre scale, XG and CNC increase the surface roughness of flax fibres, as well as their adhesion to epoxy resin with IFSS improved by 60 %, up to 22.3 MPa. At the composite scale, the treatments have a major influence on the cohesion of flax cell walls and microstructure of the biocomposites. Transverse tensile tests reveal both cohesive and adhesive interfacial failure.

Enhanced Copper Ion Adsorption by Rice Husk and Sugarcane Bagasse-based Magnetic Nanoparticles Biocomposites

Rice husk and sugarcane bagasse are biomass waste by-products of agriculture activities. High cellulose content makes them a potential material to develop. Biomass utilization is more interesting to develop due to its high cellulose content and nature abundance. Cellulose from rice husk and sugarcane bagasse is utilized as fiber in producing magnetic biocomposites. The Biocomposites can adsorb Cu(II) ions in aqueous solutions. A one-step solvothermal reaction was used to synthesize biocomposites. The amine functionalization on biocomposites was also studied for adsorption performance. The magnetic particle was generated on the surface of fiber and verified by XRD as Fe3O4. Amine group on biocomposites is also found on 570 cm-1 and 1636 cm−1 peaks for Fe-O bonds and N-H bending, respectively. Batch isothermal adsorption employing magnetic biocomposites has optimal conditions for Cu(II) ions adsorption at pH 5 for 60 minutes, with an adsorption capacity of 118.26 mg/g. The reusability of biocomposites for the next run showed a good performance at 3rd repetitions with only a decrease in adsorption capacity of 8.81%. The rice husk and sugarcane bagasse-based magnetic nanoparticles biocomposites can adsorb Cu(II) ions and potential material to develop for wastewater treatment.

Ensuring Photocatalyst Properties on Cellulosic Fabric by Using Citric Acid Modified with TiO2 Degussa P25 Nanoparticles

Citric acid, which is a type of polycarboxylic acid, is environmentally friendly, and non-harmful and it can be used as a cross-linker. Titanium dioxide (TiO2) nanoparticle is a catalyst that provides many properties for textile products with its large surface area. Present study, a mixture was prepared with different concentrations of citric acid and commercial TiO2 Degussa P25 nanopowder suspensions. Two different curing temperatures (120°C and 140°C) were applied to the cotton fabrics in the pad-dry-cure method. The adhesion of the chemicals to the fiber surface was confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometer (FT/IR) analysis. The yellowing effect caused by citric acid on cotton fabrics was eliminated with white TiO2 nanoparticles. Methylene blue was used for staining the samples. Color analyses were performed with a spectrophotometer to determine photocatalytic properties of the samples. It was determined that the samples treated with a mixture of 30 g/L citric acid and TiO2 suspensions were the most discolored samples after exposure to solar light. The photocatalyst properties of the samples were further improved by removing the aggregation of TiO2 NPs on the fiber surface with the washing procedure.

Operando Decoding of Surface Chemical and Thermal Events in Photoelectrocatalysis via a Lab-Around-Microfiber Sensor.

Operando decoding of the key parameters of photo-electric catalysis provides reliable information for catalytic effect evaluation and catalytic mechanism exploration. However, to capture the details of surface-localized and rapid chemical and thermal events at the nanoscale in real-time is highly challenging. A promising approach based on a lab-around-microfiber sensor capable of simulating photo-electric catalytic reactions on the surface of optical fibers as well as monitoring reactant concentration changes and catalytic heat generation processes is demonstrated. Due to the penetration depth of submicron size and the fast response ability of the evanescent field, the lab-around-microfiber sensor overcame the difficulty of reading instantaneous surface parameters in the submicron range. This sensor operando dismantled the changes in reactant concentration and temperature on the catalyst surface induced by light and voltage, respectively. It also decoded the impact of catalyst composition on the adsorption efficiency and catalytic efficiency across various wavelengths and determined the synchronized occurrence of pollutant degradation and catalytic thermal effects. Stable correlations between the real-time parameters and catalytic activities are obtained, helping to provide a basic understanding of the catalytic process and mechanism. This approach fills an important gap in the current monitoring methods of catalytic processes and heat production.

Characterization of Al2O3 coating of Nb fiber-reinforced TiAl composite

The Al2O3 coating was synthesized on surface of the Nb fiber via cathodic plasma electrolytic deposition (CPED) method. The microstructure and composition of the coating were elaborately analyzed. The results revealed that compact and uniform Al2O3 is fully contact with TiAl matrix and Nb fiber, which was composed of κ-Al2O3 and α-Al2O3 and successfully hold back the oxidation reactions at the juncture and refrain from formation of detrimental phases. Especially, three-dimensional characterization information can be obtained from two-dimensional converging beam electron diffraction (CBED) pattern, from which the crystal constants of Al2O3 can be obtained directly under only one applicable zone axis.

Flexible nanofiber composite solar evaporator for simultaneous interfacial evaporation and heavy metal ion adsorption

Solar driven interfacial evaporation (SDIE) is promising in harvesting fresh water because of its low cost, environmental friendless and sustainability; however, it is desirable but still difficult to achieve high efficiency heavy metal ion removal during SDIE. Here, we develop a superhydrophilic and stretchable nanofiber composite solar evaporator via carbon nanofiber (CNF) assembly on polymer fiber surface and then polydopamine (PDA) modification. The evaporation rate reaches as high as 1.456 kg m−2 h−1 with the evaporation efficiency of 91.40 %. The functional groups of PDA endow the nanofiber composite with good heavy metal ion adsorption performance that is proved to be an endothermic process, and SDIE can induce the increase of interface temperature and localized ion concentration and hence promote the Cr (VI) adsorption. One the other hand, NaCl ions are able to diffuse into body water without salt precipitation by virtue of powerful water transportation capability of the evaporation device. The dual Cr (VI) adsorption and NaCl ion diffusion channels ensure simultaneous and high efficiency Cr (VI) removal and seawater interface evaporation. SDIE accelerated heavy metal ion adsorption and the dual ion channel model provide inspiration to design multifunctional solar evaporator materials for waste water purification.

In-situ forming ultra-mechanically sensitive materials for high-sensitivity stretchable fiber strain sensors

Abstract Fiber electronics with flexible and weavable features can be easily integrated into textiles for wearable applications. However, due to small sizes and curved surfaces of fiber materials, it remains challenging to load robust active layers, thus hindering production of high-sensitivity fiber strain sensors. Herein, functional sensing materials are firmly anchored on the fiber surface in-situ through a hydrolytic condensation process. The anchoring sensing layer with robust interfacial adhesion is ultra-mechanically sensitive, which significantly improves the sensitivity of strain sensors due to the easy generation of microcracks during stretching. The resulting stretchable fiber sensors simultaneously possess an ultra-low strain detection limit of 0.05%, a high stretchability of 100%, and a high gauge factor of 433.6, giving 254-folds enhancement in sensitivity. Additionally, these fiber sensors are soft and lightweight, enabling them to be attached onto skins or woven into clothes for recording physiological signals, e.g. pulse wave velocity has been effectively obtained by them. As a demonstration, a fiber sensor-based wearable smart healthcare system is designed to monitor and transmit health status for timely intervention. This work presents an effective strategy for developing high-performance fiber strain sensors as well as other stretchable electronic devices.

Fabrication and property characterization of biocomposite based on polyamide 11 and AP1 green ramie fiber modified with epoxy

AbstractIn this article, Vietnam ramie fiber from Moc Chau, Son La province was chosen as a reinforcement for polyamide 11 (PA11) to prepare full–biocomposites. To enhance the compatibility and adhesion with the matrix, the original ramie fiber (oRF) was treated with Ca(OH)2 solution (tRF) and then modified by epoxy (mRF). Properties and structure of these fibers were characterized by tensile test, chemical composition, Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The obtained results showed the removal of hemicellulose and lignin after treatment improved the morphology and mechanical properties of the fiber. Rheology in melting state indicated the increase in the torque of PA11 matrix by adding tRF and mRF. The improvement in mechanical properties was observed for both PA11/tRF and PA11/mRF composites. After modification, epoxy on the fiber surface enhanced the adhesion and compatibility with the matrix. This led to a strong increase in Young's modulus, tensile strength and flexural strength of about 37%, 57%, and 33%, respectively. tRF and mRF also improved thermal stability of the composite as shown in TGA and DSC analysis. Finally, mRF showed a better compatibility with PA11 than tRF by observation of SEM images.

Analysis of polydisperse polymer adsorption on porous cellulose fibers

Abstract The adsorption of cationic water-soluble polymers onto negatively charged porous wood pulp fibers is an essential aspect of papermaking. Adsorption data can be displayed as a direct plot of the amount adsorbed, Γ, versus the amount of polymer added or as an isotherm plot showing the amount adsorbed versus the residual unadsorbed polymer. In either data presentation, the analysis is more transparent if the units of each axis are the same (e.g., mg/g or meq/g), giving dimensionless slopes. Values for Γmax, ΓI, f I , and Γme can be extracted from many isotherms where: Γmax is the maximum capacity of the fibers to adsorb polymer; ΓI is the y-axis isotherm intercept and gives the maximum dose that can be fully adsorbed; f I is the slope of the direct plot at ΓI, and f I is the mass fraction of the added polymer that can access interior (pore) surfaces; and, Γme is the saturated amount of polymer adsorbed on exterior surfaces. Additionally, the molecular weight distribution of the adsorbing polymer in conjunction with the adsorption isotherm can be used to estimate the molecular weight distributions of adsorbed polymer on interior and exterior fiber surfaces as functions of the polymer dose.

Performance comparison of different filters based on fibre optic lighting systems and evaluation of architectural lighting effects

Plastic optical fiber lighting is a feasible green lighting method for buildings. This study first derives a mathematical model for the focused light energy absorbed by optical fibers. Based on the variable relationships in the mathematical model, the cooling mechanism of plastic optical fibers was obtained. Secondly, a dual-axis automatic sun-tracking concentrating lighting equipment capable of carrying nine Fresnel lenses was designed. The equipment was used to compare the filtering and cooling effects of two types of filter devices: infrared filters and heat-insulating film. The cooling and lighting effects of these two types of filter devices were also evaluated. Subsequently, the impact of fiber loops on lighting was discussed. Finally, the b2 and b3 modules of the dual-axis automatic sun-tracking concentrating lighting equipment were applied in dark stairwells. The results indicate that the temperature of optical fibers can be reduced by using filtering devices and enhancing heat radiation and convection on the surface of optical fibers. Infrared filters exhibit better cooling and lighting effects than heat-insulating film. Looping the fiber cable reduces the effect of fiber lighting, and the higher the number of loops, the higher the loss of fiber lighting. The dual-axis automatic sun-tracking concentrating lighting equipment increased the illuminance value in the stairwells to over 50 lux, showing great application potential in architectural lighting.

Protecting against micropollutants in water storage tanks using in-situ TiO2 coated quartz optical fibers

Photocatalyst-coated optical fibers (P-OFs) using UV-A LEDs offer a highly promising solution for the degradation of micropollutants within municipal, reuse, industrial or home distribution systems, by integrating P-OFs into water storage tanks. P-OFs have photocatalysts attached to bundles of optical fibers, enabling their direct deployment within tanks. This eliminates the necessity for photocatalyst slurries, which would require additional membrane or separation systems. However, a current limitation of P-OFs is light management, specifically light oversaturation of the coated photocatalysts and short light transmission distances along fibers. This study overcomes this limitation and reveals strategies to improve the light dissipation uniformity along P-OFs, and demonstrates the performance of P-OFs on degrading a model micropollutant, carbamazepine (CBZ). Key tunable variables of fibers and light emission conditions, including photocatalyst coating patchiness (p), minimum light incident angles (θm), radiant flux launched to fibers (Φi), and fiber diameters (D), were modeled to establish their relationships with the light dissipation uniformity in TiO2-coated quartz optical fibers (TiO2-QOFs). We then validated modeling insights by conducting experiments to examine how these variables influence the generation of evanescent waves which are localized energy on fiber surfaces, leading to either photocatalyst activation or the recapture of unused light back into fibers. We observed substantial enhancements in evanescent waves generation by decreasing p and increasing θm, resulting in uniform light dissipation which reduces light oversaturation and improves light transmission distances. Moreover, these optimizations led to a remarkable three-fold improvement in CBZ degradation rates and a 65% reduction in energy consumption. Such improvement substantially reduces the capital and operational cost and enhances practicality of energy-efficient photocatalysis without additional chemical oxidants for micropollutant degradation in water storage tanks.

Facile physical entrapment of halochromic dye via UV-photografting for the fabrication of colorimetric cotton sensors to detect toxic ammonia gas

Textile-based halochromic gas sensors are useful for detecting volatile organic compounds (VOCs) such as ammonia, because they undergo changes that are distinguishable to the naked eye. Herein, we report the UV photografting system we developed for the fabrication of halochromic cotton sensors with reduced amounts of salt, resources, and effluents. First, 4-hydroxycoumarin-based dye (HD) was synthesized as a halochromic indicator, where after the synthesized dye, monomer, and photoinitiators were introduced to a dye bath to fabricate the UV photografting system. This system was produced by grafting monomers on a fiber surface under UV light irradiation to formulate a polymer network that entraps dye molecules. A series of different monomer concentrations and photoinitiators were introduced to the dye bath. Subsequently, the dyeability and gas detection performance of the fabricated cotton sensors were evaluated. In addition, fastness and reusability tests were performed to ensure the fabricated cotton sensors were durable and sustainable. The dyeability of the fabricated cotton sensors increased as the monomer concentration increased and the color change upon exposure to ammonia gas followed the same tendency. The fabricated cotton sensor prepared with the highest monomer concentration underwent a distinctive color change upon exposure to ammonia gas for 300 s (ΔE > 15). Furthermore, the cotton sensor exhibited remarkable durability to washing (wash fastness level: 5, ΔE maintenance rate after washing: ∼85 %) and rubbing (rubbing fastness level: 4/5, ΔE maintenance rate after rubbing: ∼95 %). Reusability testing of the fabricated cotton sensors showed that the halochromic property was retained after repeated washing (10 cycles). The results confirmed that the UV-induced photografting performance had been optimized and suggested that UV-induced photografting offered an eco-friendly alternative to conventional dyeing for the fabrication of halochromic textile sensors.

Effects of cellulose diameter on the formation and rheological properties of edible walnut oleogels structured by cellulose nanofiber

Oleogel of edible vegetable oils structured by cellulose nanofiber (CNF) via emulsion-templated method has attracted many interests due to its potential substitute of saturated or trans-fats in food industry. The gelation mechanism of liquid oil is dominated by different intermolecular non-covalent interactions, while the type and strength of these interactions are greatly influenced by the structure and properties of the gelator factors. Here, the effect of different CNF diameter ranges (5–10 nm, 10–20 nm and 20–60 nm) was investigated for CNF-based walnut oil oleogels, under the same fiber length and surface carboxyl content of CNFs. The results showed that CNFs with diameters of <20 nm exhibited better emulsification properties, and effectively restrained droplet size increasing and aggregation, compared to CNF with diameter of 20–60 nm. The resultant oleogels with smaller CNF diameter exhibited higher oil-binding capacity (OBC, ∼85%) and better thermal stability of the resultant oleogels. More compact structure and stronger mechanical strength of oleogels were achieved with CNF diameters of <20 nm, which was verified by stronger textural hardness of the oleogels (0.46 N), as well as higher storage modulus (up to 1.1 × 105 Pa) and apparent viscosity in rheological measurement. The enhanced OBC and structure strength of oleogels with smaller CNF diameter could be attributed to the enhanced hydrogen bonding interactions between CNF molecules and CNFs with oil molecules during oleogelation, as the rigorously fibrillation exposed more surface hydroxyl groups as accessible hydrogen bonding sites during CNF preparation. This study improved the understanding about gelling properties of CNFs with different fiber diameters and provided an empirical basis for the construction of CNF-based oleogels with tunable hydrogen bonding interactions.

Effect of nanosilica and fiber on mechanical properties and microstructure of recycled coarse aggregates road concrete

Recycled coarse aggregate has its own characteristics of large porosity, high water absorption and high crushing index, which adversely affects the mechanical strength and durability of recycled aggregate concrete. In this study, the mechanical properties, durability and microstructure of recycled aggregate concrete (RAC) modified with nano-SiO2 (NS) and fibres were investigated to prepare road RAC, using NS polypropylene fibres (PPF) and basalt fibres (BF) as test variables. Compared with RAC only incorporating NS, NS and fibre synergism can significantly enhance the mechanical properties of recycled concrete, compressive strength increased by 27–51 %, flexural strength increased by 12 %, and abrasion resistance increased by 25–72 %. The synergistic effect of NS and PPF significantly improves the frost resistance of recycled concrete. NS has a volcanic ash effect which can react with calcium hydroxide to produce a large number of C-S-H in the secondary hydration reaction, making the internal structure of the cement matrix denser. Interfacial transition zone microstructure is more compact, thus interfacial transition zone porosity is effectively reduced. The hydration products are attached to the fibre surface, which enhances the bonding ability between the fibers and matrix. Therefore, the fibres effectively inhibit the generation and development of internal micro-cracks. NS optimises the internal pore structure of recycled aggregate concrete and enhances the interfacial transition zone, and NS synergistically with PPF can improve the strength and durability of various mechanical properties of recycled concrete. The research results provide the scientific basis for the application of road RAC.

Spider silk-inspired heterogeneous interphase featuring hybrid interaction for simultaneously improving the interfacial strength and fracture toughness between carbon fiber and epoxy by regulating hydrogen bond density

Designing advanced fiber-reinforced polymer composites through biological inspiration proved to be a crucial strategy for overcoming limitations in simultaneously enhancing the strength and toughness of composites. To achieve simultaneous improvement in the interfacial strength and toughness between carbon fiber (CF) and epoxy, a spider silk-inspired interphase featuring hybrid interaction was constructed by introducing hyperbranched polyamide-amine (HPAA) and graphene oxide (GO) onto the surface of CF. The results suggested that manipulating the feed ratio to adjust the branching degree of HPAA allowed for the attainment of various hydrogen bond densities. The fiber surface with high hydrogen bond density provided more hydrogen bond interaction sites to promote the deposition of GO. Benefitting from the ameliorative interfacial adhesion force, surface energy and interface thickness, impressive improvements of 94.5 % and 110.0 % in respective interfacial strength and fracture toughness over those of untreated CF/EP composites were achieved for functionalized CF/EP composites. The enhancement mechanism of interfacial performance was attributed to the formation of a “nano-fishnet” structure, which improved the stress transformation efficiency and consumption of external energy absorbed by hydrogen bonds. The method of regulating the branching degree of hyperbranched polymers and hydrogen bond density has opened an advanced way for surface modification of high-performance fibers.

Effects of surface modification on mechanical properties and electromagnetic interference shielding properties of carbon fiber/silk fiber hybrid composites

AbstractIn this paper, a hybrid approach was employed by integrating a high‐modulus, high‐tensile‐strength carbon fiber fabric (CFF) with a low‐density, high‐toughness silk nonwoven fabric (SNWF) to fabricate CFF‐SNWF reinforced epoxy (CFF‐SNWF/EP) hybrid composites. Through the surface freeze‐induced self‐assembly process, the multiscale hybrid modified layers were successfully constructed on the surfaces of both CFF and SNWF. This novel approach effectively enhanced the interfacial strength of the hybrid fibers (HFs). Comparing the performance of the modified composites with unmodified CFF reinforced epoxy (CFF/EP), significant improvements in both tensile strength and interlaminar shear strength were observed. Specifically, the tensile strength and interlaminar shear strength of the modified composites reached 626.7 and 39.16 MPa, a rise scope of 17.1% and 14.8%, respectively. In addition, the hybrid fibers reinforced polymers (HFRPs) exhibited a superior electromagnetic interference (EMI) shielding capabilities. For insistence, the modified CFF/EP with a thickness of 2.0 mm showed an impressive EMI shielding effectiveness value of 50 dB. These findings underscore the promising application potential of CFF‐SNWF/EP hybrid composites, particularly in the field of consumer electronics.Highlights The surface of hybrid fiber was modified by PDA‐GO‐OCNTs‐WPU. Multi‐scale structure contributes a lot in composite performance. Hybrid effect before and after interfacial modification is performed. The hybrid interface modification and hybrid structure were analyzed.