Carbon Fiber Surface Research Articles

Research on Microwave Pyrolysis Recovery and Reuse Performance of Carbon Fiber Composites.

Carbon fiber-reinforced resin matrix composites find extensive applications across various industries. However, their widespread use also generates significant waste, leading to resource depletion and environmental concerns. Studying the production of composite materials using recovered carbon fiber is imperative to mitigate the environmental impact associated with waste from carbon fiber-reinforced resin matrix composites and optimize resource utilization. In this study, carbon fiber was reclaimed using the microwave pyrolysis-oxidation process. The reclaimed carbon fiber underwent a cutting process to produce shorter carbon fibers tailored to specific requirements, which were then used to fabricate composite plates reinforced with epoxy resin. The mechanical characteristics of the composite were analyzed, along with SEM, XPS, infrared, Raman, and contact angle analyses conducted on the recovered carbon fiber. The test findings suggested minimal variation in the surface morphology of the recovered carbon fiber materials. Post-recovery, an increase in the quantity of oxygen-containing functional groups was observed on the carbon fiber surface. Additionally, the contact angle between the carbon fiber surface and the epoxy adhesive decreased. The mechanical properties of the composite produced from the recovered carbon fiber decreased, including the impact strength, tensile strength, and bending strength, with the impact strength dropping by 24.14%, tensile strength by 15.94%, and bending strength by 8.24%, while maintaining overall reusability, thus paving the way for the comprehensive utilization of carbon fiber resources.

Multiscale enhancement of carbon/carbon composite performance by self-assembly of sulfonated graphene with silane-treated carbon fibers

The application prospects of carbon/carbon composites are greatly limited by interfacial cracks and pores caused by binder pitch displacement and cracking during high-temperature carbonization. In this study, silane coupling agent was coated on the surface of oxygen plasma-treated carbon fibers (CFs) and subsequently electrostatically self-assembled with sulfonated graphene (SG) to improve the interfacial bonding between filler and CTP. The results indicate that the tensile strength of carbon fiber treated with silane coupling agent increased by 19 % compared to untreated CF. This increase in strength may be related to the layer of silane coupling agent that repaired the grooves and imperfections on the CF surface. The addition of SG not only improves the distribution characteristics of the fibers, allowing the silane-treated CF to play a greater role in the matrix, but also creates a three-dimensional hydrogen-bonded cross-linking between the SG and the coal tar pitch (CTP) on the surface of the fibers. This inhibits CTP displacement and pyrolysis, achieving a tight bonding of the fiber to the matrix. The composites' structural integrity and mechanical properties were significantly improved due to the synergistic effect of silane-treated CF and SG. The compressive strength was 216.98 MPa, with a flexural strength of 54.78 MPa, 250 % higher than the untreated carbon fiber-reinforced composites. Additionally, the porosity decreased by 31.5 %, and the antioxidant properties increased. The study presents a potential solution to improve the performance of carbon/carbon composites by using the silane-treated CF-SG multiscale reinforced phase.

Pd/TiO2 decorated carbon fibers as an efficient anode catalyst for methanol electro‐oxidation

AbstractIn this study, Pd/TiO2 decorated carbon nanofibers (Pd/TiO2@CNFs) and Pd@CNFs were prepared by the impregnation method for application in direct methanol fuel cells (DMFCs). Pd and TiO2 particles were supported on the surface of carbon fibers. Noticeably, When the mass fraction of PdCl2 added is 4%, the Pd@CNFs catalyst (Pd‐4@CNFs) showed higher electrocatalytic activity and stability, which were about 28.4 and 13.2 times higher than those of commercial Pd/C catalyst, respectively. On the basis of Pd‐4@CNFs catalyst, TiO2 with a mass fraction of 10% was added to produce Pd/TiO2@CNFs catalyst (Pd‐4/TiO2‐10@CNFs). The electrocatalytic activity of Pd‐4/TiO2‐10@CNFs increased to 3,850.4 A·g−1, which was 31.9 times higher than that of commercial Pd/C catalysts. These results demonstrated that the novel Pd/TiO2@CNFs catalyst is expected to be an efficient and durable catalyst for DMFC.

Understanding the Interface Enhancement Mechanisms of CFRP with the Polydopamine-Polyetheramine Interphase at the Molecular Level.

In this work, polydopamine (PDA) and polyetheramine D230 were selected to construct the PDA-D230 interphase between the carbon fiber (CF) and epoxy matrix. Density functional theory (DFT) and molecular dynamics (MD) simulations were performed to explore the interface enhancement mechanisms of a carbon fiber reinforced polymer (CFRP) with the PDA-D230 interphase from the molecular level. The adsorption characteristics of a PDA molecule on the CF surface were investigated using the DFT method. The results show that stronger π-π stacking interactions are formed due to the structure and orientation preference of the PDA molecule. The interfacial structures and properties of CFRP with the PDA-D230 interphase are derived from MD simulations. The PDA-D230 interphase on the CF surface induces stronger interfacial interaction energy, leading to the better load transfer between the CF and epoxy matrix. The existence of the PDA-D230 interphase on the CF surface can decrease the mean-square displacement (MSD) value and the free volume fraction of CFRP, which restricts the movement of epoxy atoms and inhibits the translational and rotational motion of epoxy chains. Compared with the epoxy using pristine CFs as reinforcement, the interfacial shear stress (ISS) of CFRP with the PDA-D230 interphase is improved by 13.1%. Our results provide valuable insights into the interface characteristics of CFRP with the PDA-D230 interphase, which are of great significance for exploring the strengthening mechanisms for CFRPs with the PDA-D230 interphase.

Mechanical improvement of carbon fiber/epoxy composites by sizing functionalized carbon nanotubes on fibers

AbstractA sizing agent mainly consisting of polyethersulfone and acidified multi‐walled carbon nanotubes (MWCNT) was developed for surface modification of carbon fibers (CF) to enhance the interfacial bond and to form carbon fiber‐carbon nanotube (CF‐MWCNT) multiscale reinforcements. To prepare the modified carbon fiber/epoxy resin composites (CFRP), a vacuum molding technique was used in this study. The effects of the MWCNT‐containing sizing agent on the morphology and chemical structure of the CF surface were observed by scanning electron microscopy and Fourier transform infrared spectroscopy. The influence of MWCNT length and content on the mechanical properties of CFRP were also studied. The experimental results showed that the strength of the CFRP decreased with the increase of MWCNT length, and the MWCNT with a content of 0.05 wt% had a good reinforced effect on the CFRP. After the sizing treatment, the interlaminar shear strength (ILSS) of the CFRP is increased. These enhancements are attributed to the improved mechanical bonding and chemical bonding between CF and resin matrix. The MWCNT provides nanosized rough surface to CF and these acidified MWCNTs attached to the surface of CF with polar oxygen‐containing functional groups improve the compatibility with reinforcement and resin matrix.Highlights Carbon fiber was modified by a sizing agent mainly consisting of polyethersulfone and acidified carbon nanotube (CNT). CNTs enhance the interfacial chemical bonding and mechanical bonding. The CNT length affects the mechanical properties of the carbon fiber/epoxy resin composites (CFRP). The modified carbon fiber has enhanced the mechanical properties of the CFRP.

Synergistic cooperation of a Magnolol-based waterborne cross-linkable PEEK sizing agent and click chemistry to construct exceptional solvent-resistance and interfacial properties of CF/PEEK composites

Despite the impressive strides on waterborne cross-linkable sizing agents for carbon fiber (CF)-reinforced polyether ether ketone (PEEK) composites, the vast majority of polymer precursors employed for sizing agents in existing researches are derived from petroleum resources. On the other hand, the notable influence of the adhesive strength between sizing agent and CF on the interfacial properties of composites has been consistently disregarded. Herein, a waterborne cross-linkable sizing agent was prepared capitalizing on naturally existing magnolol. Meanwhile, sulfhydryl groups were chemical-grafted on the surface of CF via click reaction, setting stages for subsequent interaction with magnolol units via a second click reaction to effectively enrich the force between CF and sizing layer. As a unique feature of the system, the inherent mechanism of the sizing coating layer comprises self-crosslinking of the orchestrated propenyl groups toward sturdy structures during hot-pressing, contributing to unrivalled solvent-resistance and unorthodox interfacial robustness. As a result, the bending strength, interlaminar and interfacial shear strength of the derived composites were promoted by 35.48 %, 47.87 % and 61.03 %, respectively. Noteworthy, the mechanical properties of Sized-CF composites were well-preserved after solvent aging treatment. Therefore, this protocol developed a novel bio-based waterborne cross-linkable sizing agents of PEEK derivative, laying a good foundation for advanced CF/PEEK composites with excellent interfacial performance.

Precisely adjusting the interface adhesion of carbon fiber/epoxy composites by regulating the micro-configuration of graphene oxide nanosheets on the fiber surface

Different micro-configurations of graphene oxide (GO) nanosheets on the carbon fiber (CF) surface, including the distribution and size, endow CF-GO enhanced microstructure and physiochemical characteristics of the CF/epoxy (CF/EP) composites. In order to investigate the relationship between the GO micro-configuration and the interfacial adhesion of the CF/EP, here, polyether imide (PEI)-GO heterogeneous reinforcement was grafted onto the CF surface (CF-PEI-GO) by precisely modulating the mass ratio of CFs to GO. The micro-configuration and properties of the CF-PEI-GO hybrids, together with the thickness and modulus variation of the interface layer are investigated, in order to make certain on the enhancement mechanisms of both interfacial and mechanical performances. Optimal performances of the CF-PEI-GO/EP composites are achieved with a CF/GO mass ratio of 40:1. The uniformly “upright” distribution of moderate-size GO on the CF surface induces a synergistic effect of improved mechanical interlocking, chemical bonding, high wettability, and effective interface adhesion, which are stemmed from higher surface roughness, more active functional groups, higher surface energy, and wider interface thickness with gradient descent modulus. This work presents a valid, practical strategy to precisely control the interfacial adhesion of the CF/EP composites by adjusting the micro-configuration of 2D materials on the fiber surface.

Optimized Fabrication of Carbon-Fiber Microbiosensors for Codetection of Glucose and Dopamine in Brain Tissue.

Dopamine (DA) signaling is critically important in striatal function, and this metabolically demanding process is fueled largely by glucose. However, DA and glucose are typically studied independently and, as such, the precise relationship between DA release and glucose availability remains unclear. Fast-scan cyclic voltammetry (FSCV) is commonly coupled with carbon-fiber microelectrodes to study DA transients. These microelectrodes can be modified with glucose oxidase (GOx) to generate microbiosensors capable of simultaneously quantifying real-time and physiologically relevant fluctuations of glucose, a nonelectrochemically active substrate, and DA, which is readily oxidized and reduced at the electrode surface. A chitosan hydrogel can be electrodeposited to entrap the oxidase enzyme on the sensor surface for stable, sensitive, and selective codetection of glucose and DA using FSCV. This strategy can also be used to entrap lactate oxidase on the carbon-fiber surface for codetection of lactate and DA. However, these custom probes are individually fabricated by hand, and performance is variable. This study characterizes the physical nature of the hydrogel and its effects on the acquired electrochemical data in the detection of glucose (2.6 mM) and DA (1 μM). The results demonstrate that the electrodeposition of the hydrogel membrane is improved using a linear potential sweep rather than a direct step to the target potential. Electrochemical impedance spectroscopy data relate information on the physical nature of the electrode/solution interface to the electrochemical performance of bare and enzyme-modified carbon-fiber microelectrodes. The electrodeposition waveform and scan rate were characterized for optimal membrane formation and performance. Finally, codetection of both DA/glucose and DA/lactate was demonstrated in intact rat striatum using probes fabricated according to the optimized protocol. Overall, this work improves the reliable fabrication of carbon-fiber microbiosensors for codetection of DA and important energetic substrates that are locally delivered to the recording site to meet metabolic demand.

Influence of Polyetheretherketone radicals on interfacial interaction with carbon fiber and crystal formation of Polyetheretherketone at the interphase

This study investigates the impact of free radicals present in polyetheretherketone (PEEK) on its interfacial adhesion with reinforcing fibers and the resulting crystal formation at the interphase. Microdroplet tests revealed that the interfacial shear strength between PEEK and carbon fiber (CF) was enhanced under increased preparation temperatures or prolonged holding times in the molten state, corresponding to an upsurge in PEEK radicals, elucidated by electron spin resonance and melt rheological behavior analyses. The post-microdroplet testing fracture surface and PEEK crystal structure near the fiber were investigated through micro-Raman spectroscopy under varying reinforcing fiber types and functional group concentrations (e.g., -OH and -COOH) on the CF surface. The results revealed that PEEK crystal formation along the CF axis at the interphase is driven by noncovalent interfacial interactions, such as π interactions and hydrogen bonds. Conversely, covalent interfacial interactions suppress crystal formation.

Interfacial enhancement by constructing a “flexible-rigid” structure between high-modulus fillers and low-modulus matrix in carbon fiber/silicone rubber composites

Silicone rubber (SR) has excellent resistance to high temperatures, and carbon fiber (CF) is a commonly reinforced material. However, the application of carbon fiber in SR composites is limited by the large difference in modulus between the two materials. In order to improve the interfacial bonding of the composites and to exert the reinforcement of carbon fibers, a modulus transition interface, a “flexible-rigid” structure was constructed between CF and SR by coating polydopamine-polyethyleneimine@silica (PDA-PEI@SiO2) on the carbon fiber surface. The results show that the “flexible-rigid” structure of the PDA-PEI@SiO2 layer not only enhanced the mechanical properties but also improved the thermal resistance and wave-transmission properties of the CF/SR composites. Surface microscopy and structural analysis showed that the “flexible-rigid” structure was successfully coated on the fiber surface, and significantly improved the roughness of the fiber surface. It provided the mechanical meshing between the fiber and matrix when the CF/SR composites were subjected to the tensile loads. The tensile strength and elongation of the SR composite with CF-A-E@8SiO2 were 37.16 % and 27.46 % higher than that with unmodified CF, respectively. The electrical test showed that the “flexible-rigid” structure could reduce the dielectric constant and dielectric loss of CF/SR composites, thereby improving the wave-transmission properties. Further mechanism analysis of the interfacial bonding showed that abundant hydrogen bonds in the “flexible-rigid” structure at the interface promoted stress dissipation and avoided stress concentration. Meanwhile, the formation of Si-O-Si with high bonding energy also protected the interface from destruction. The thermogravimetric analysis (TGA) found that the introduction of Si-O-Si bonds could significantly improve the thermal resistance of the CF/SR composites at 350 °C for 2 h. It provides guidance for the improvement of the interface bonding in the fiber/rubber composite as well as its functionality.

Constructing a Novel Moderately Modulus "Rigid-Flexible" Structure with Synergistic Reinforcement on the Carbon Fiber Surface to Enhance the Mechanical Properties of Carbon Fiber/Epoxy Composites at Elevated Temperatures.

To improve the mechanical performance of carbon fiber (CF)/epoxy composites in high-temperature environments, a moderately modulus gradient modulus interlayer was constructed at the interface phase region of composites. This involved the design of a "rigid-flexible" synergistic reinforcement structure, incorporating rigid nanoparticle GO@CNTs and a flexible polymer polynaphthyl ether nitrile ketone onto the CF surface. Notably, at 180 °C, compared to commercial CF composites, the CF-GO@CNTs-PPENK composites displayed a remarkable improvement in their mechanical characteristics (interfacial shear, interlaminar shear, flexural strength, and modulus), achieving enhancements of 173.0, 91.5, 225.7, and 376.4%, respectively. The principal reason for this the moderately modulus interface phase composed of GO@CNTs-PPENK (where GO and CNTs predominantly consist of carbon atoms with sp2-hybridized orbitals, forming highly stable C-C structures, while PPENK possesses a "twisted non-coplanar" structure), which exhibited resistance to deformation at high temperatures. Moreover, it greatly improved the mechanical interlocking, wettability, and chemical compatibility between CF and the epoxy. It also played a crucial role in balancing and buffering the modulus disparity. The interface failure behavior and reinforcement mechanisms of the CF composites were analyzed. Furthermore, validation of the presence of a moderately modulus gradient interlayer at the interface phase region of CF-GO@CNTs-PPENK composites was performed by using atomic force microscopy. This study has established a theoretical foundation for the development of high-performance CF composites for use in high-temperature fields.

Studies toward Morphological Changes of Silver/Carbon Fiber Composites and Their Optimization for High-Performance Electrochemical Electrodes

The integration of micro/nanostructured metal/metal oxides with carbon-based materials has emerged as a promising approach for developing electrochemical electrodes. However, the fabrication of such hybrids entails complex and multistep procedures involving the grain boundaries and interfaces between the constituent materials, thus, degrading the overall performance. Herein, we report a facile electrothermal process (ETP) for the scalable fabrication of hybrid carbon fiber (CF) sheets integrated with tunable morphology of silver micro/nanoparticles. The application of an electric field across the layered film, consisting of AgNO3 and CF, enabled the rapid dissipation of thermochemical energy in an open-air environment via ETP. The ETP facilitated ultrafast heat dissipation within a few milliseconds, leading to the rapid decomposition of AgNO3, which resulted in the formation of liquefied Ag on the CF surface affording a reduced Ag-CF composite with adjustable structures through input power. The capability of ETP driven by controlling duration and number of electrical pulses was demonstrated by examining the corresponding physiochemical and electrochemical characteristics of the resulting composite. The Ag-CF composite fabricated using three cycles of a screened ETP pulse (1500 W and 75 ms for power and duration) acted as a supercapacitor electrode demonstrating excellent area capacitance (13 F/cm2) and exceptional capacitance retention (98% after 10,000 cycles). Thus, the utilization of ETP can provide manufacturing strategies enabling scalable synthesis of functional hybrids in vacuum-free ambient environments within milliseconds. These hybrids possess unique interfaces and particle boundaries, exhibiting considerable potential for diverse electrochemical applications.

Construction of multilayer carbon magnetic heterostructures on the surface of carbon fibers to improve the absorption performance

AbstractThis study utilizes the strong complexation effect of polydopamine on metal ions and constructs multilayer carbon magnetic heterostructures on the surface of carbon fibers through the in situ reduction method, thereby obtaining a new type of multilayer carbon‐based composite absorbing material. The absorption properties at different layers were analyzed and compared through various characterization methods. Finally, the double‐layer structure demonstrated outstanding electromagnetic wave absorption characteristics, exhibiting a wide effective absorption bandwidth of 7.24 GHz and robust absorption of −44.48 dB, all within a mere thickness of 3.5 mm. Therefore, excellent market prospects for this material are anticipated.Highlights A multilayer carbon magnetic heterostructure absorbing material was constructed on micrometer‐scale carbon fibers. The test results show that a wide effective absorbing bandwidth of 7.24 GHz and a minimum reflection loss of −44.48 dB are obtained when the composite thickness is 3.5 mm. The prepared multilayer absorbing composites can adapt to a variety of application scenarios and have excellent application prospects in the industry. The self‐polymerization of dopamine and complexation of metal ions were used to construct multilayer absorbing materials, and the dielectric loss and magnetic loss capacity of the carbon fibers improved.

Effect of polyphenylene sulfide sulfone sizing agent on interfacial, thermal, and mechanical properties of carbon fiber

AbstractPolyphenylene sulfide sulfone (PPSS) was synthesized by one‐step method and utilized as a sizing agent for carbon fibers. The effects of various monomer ratios, reaction time, and reaction temperature were investigated on the molecular weight of PPSS. The thermal analysis revealed that the product PPSS exhibited a glass transition temperature exceeding 215.5°C, indicating exceptional thermal stability. After PPSS sizing treatment, the grooves on the surface of carbon fibers were filled, resulting in a substantial enhancement of the microinterface properties. The surface energy was increased by 8.2%, while the maximum weight loss temperature was 27.8% higher than that of the commercial carbon fiber. The tensile strength of the carbon fiber after heat treatment reached 2196 MPa, representing a 45.9% increase over that of the commercial carbon fiber.

Sustainable and Low-Cost Electrodes for Photocatalytic Fuel Cells.

Water pollutants harm ecosystems and degrade water quality. At the same time, many pollutants carry potentially valuable chemical energy, measured by chemical oxygen demand (COD). This study highlights the potential for energy harvesting during remediation using photocatalytic fuel cells (PCFCs), stressing the importance of economically viable and sustainable materials. To achieve this, this research explores alternatives to platinum cathodes in photocathodes and aims to develop durable, cost-effective photoanode materials. Here, zinc oxide nanorods of high density are fabricated on carbon fiber surfaces using a low-temperature aqueous chemical growth method that is simple, cost-efficient, and readily scalable. Alternatives to the Pt cathodes frequently used in PCFC research are explored in comparison with screen-printed PEDOT:PSS cathodes. The fabricated ZnO/carbon anode (1.5 × 2 cm2) is used to remove the model pollutant used here and salicylic acid from water (30 mL, 70 μM) is placed under simulated sunlight (0.225 Sun). It was observed that salicylic acid was degraded by 23 ±0.46% at open voltage (OV) and 43.2 ± 0.86% at 1 V with Pt as the counter electrode, degradation was 18.5 ± 0.37% at open voltage (OV) and 44.1 ± 0.88% at 1 V, while PEDOT:PSS was used as the counter electrode over 120 min. This shows that the PEDOT:PSS exhibits an excellent performance with the full potential to provide low-environmental-impact electrodes for PCFCs.

Carbon Fiber Reinforced Recycled Polypropylene/Polyolefin Elastomer Composites with High Mechanical Properties.

The treatment of waste plastics has gradually become a hot topic in the current scientific community. In response to the needs for high-impact performance R-PP-based composites, carbon fiber (CF)-reinforced polyolefin elastomer (POE)/recycled polypropylene (R-PP) composite (CF/POE/R-PP) was prepared by the mechanical blending method, and its mechanical and thermal properties were systematically studied. It was found that the CF could effectively improve the bending and notch impact strength as well as enhance the thermal stability of POE/R-PP. Furthermore, a stable and dispersed composite interface formed by the combination of maleic anhydride-grafted polypropylene (PP-g-MAH) with the surface of CF and the fusion alkyl chains in R-PP and POE further enhanced the CF's reinforcing effect. As a result, the addition of 9 wt.% CF successfully improved the heat resistance of the composite material, and the residual carbon content increased by 97.84% after sintering. The composite toughening of POE and CF effectively improved the impact strength of the composite material, with a maximum increase of over 1000%. This study ultimately resulted in a high-impact-resistant composite material.

Improving the thermal conductivity of an epoxy composite with chemically boron nitride-grafted carbon fiber

The rapid progress of electronic devices like electric vehicles, smartphones, and IoT systems has fueled the demand for compact, high-performance batteries. However, a critical challenge arises from heat accumulation within these devices, leading to malfunctions and reduced efficiency. To address this, efficient heat dissipation is crucial, with thermal interface materials (TIMs) widely used for heat transfer. While polymers are favored for TIMs due to their ease of processing and electrical insulation, their low thermal conductivity poses limitations. In this study, a solution is proposed by chemically grafting boron nitride (BN), a ceramic-based filler, onto carbon fiber (CF) surfaces. This BN-g-CF hybrid filler, formed through a reaction between acyl chlorides and amine groups, exhibits superior compatibility with polymer matrix. Characterization confirms successful treatment, and thermal conductivity measurements show a remarkable enhancement, positioning the BN-g-CF/epoxy resin composite as a promising solution for efficient thermal management in various electronic industries.

Preparation of biomimetic reinforced modified carbon fiber composites and study of their friction properties

Because aluminum-based parts cannot be used for long-term applications in large load-wear environments, nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composites were successfully prepared in this study for that purpose. By adjusting the plating solution ratio, nickel–tungsten was used as a carrier to introduce molybdenum disulfide nanoparticles, forming a nickel–tungsten/molybdenum disulfide composite coating on the surface of carbon fibers. To enhance the interfacial bonding strength between the carbon fiber and aluminum matrix, a laser was employed to induce the formation of a honeycomb-like structure on the surface of the aluminum base. This increased the contact area between the carbon fiber, aluminum matrix, and epoxy resin adhesives, forming a nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composite material. The performance of this composite material was tested and analyzed. The results demonstrated that compared with the carbon fiber/aluminum composite material, the shear strength of the nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composite material was increased by 129.7 %, and the friction coefficient and wear rate were reduced by 54.8 % and 83 %, respectively. Next, investigation of the mechanism underlying the honeycomb structure's contribution to the adhesive strength of the composites and their resistance to shear load revealed that the wear-resistant mechanism of molybdenum disulfide nanoparticles reinforced the nickel–tungsten composite coatings. The preparation and study of nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composites provide a reference for expanding the applications of aluminum-based composite materials to meet the service requirements of complex environments.

Collaboration of Fenton reaction with a tannin acid-based hyperbranched waterborne polyurethane sizing agent for synergistic enhancement of the CF/PA6 composite interfacial properties

The adhesive strength between the sizing agent and carbon fiber (CF) plays a pivotal role in determining the interfacial properties of composites. Unfortunately, this critical aspect has been consistently overlooked. In this study, a hyperbranched waterborne polyurethane (HWPU) sizing agent was prepared by biogenetic derived raw materials including gallic acid as well as tannic acid. Meanwhile, iron ion was introduced onto the surface of CF by Fenton reaction, forming a heterogeneous structure to elevate the mechanical interlocking between the CF and resin. Chelation of TA with iron ion on the fiber surface effectively enhanced the adhesion between sizing agent and CF. The mechanical properties of the newly designed composites were systematically investigated. The results showcase a significant enhancement in both flexural strength and interlaminar shear strength (ILSS) compared to untreated CF, marking improvements of 54.3% and 60.0%, respectively. Furthermore, the interfacial shear strength (IFSS) test exhibited a 71.2% augment. In conclusion, this approach presented a highly promising concept aimed at improving the interfacial performance of CF composite materials.

Mitigating Crack Propagation in Hybrid Composites: An Experimental and Computational Study

The exceptional properties of carbon nanotubes (CNTs) make them ideal nanofillers for various composite materials. In carbon fiber-reinforced polymer (CFRP) composites. CNTs can be grown on the carbon fiber surface to act as a third interface between the fiber and the matrix. However, it was established that the uncontrolled random growth of CNTs could exacerbate delamination in composite structures. Thick nanofiller films could hinder the epoxy from seeping into the carbon fiber, resulting in insufficient interlaminar strength. Hence, the density and distribution of nanofillers play a crucial role in determining the hybrid composite fracture mechanisms. In this investigation, CNTs were grown using the low-temperature technique into specific patterns over carbon fibers to discern their derived composites’ fracture properties. The composite fracture energy release was probed using a double cantilever beam (DCB) test setup and digital image correlation (DIC) to monitor interlaminar crack propagation. A standard finite element simulation model based on the cohesive zone method (CZM) was also utilized to delineate fracture behaviors of the various composite configurations. Results conclude that a coarser pattern of CNT growth enhances resistance to crack propagation, thus improving the interlaminar fracture toughness of a composite structure.