Fiber Resin Research Articles

Enhanced Interfacial Properties of Carbon Fiber/Polymerization of Monomers Reactants Method Polyimide Composite by Polyimide Sizing.

Carbon fiber (CF)-reinforced polyimide (PI) resin matrix composites have great application potential in areas such as rail transport, medical devices, and aerospace due to their excellent thermal stability, dielectric properties, solvent resistance, and mechanical properties. However, the epoxy sizing agent used for traditional carbon fiber cannot withstand the processing temperature of polyimide resin, of up to 350 °C, resulting in the formation of pores or defects at the interface between the fiber and the resin matrix, leading to the degradation of the overall composite properties. To overcome this problem, in this study, a low-molecular-weight thermosetting polyimide sizing agent was prepared and the processability of the sized carbon fiber was optimized by a thermoplastic polyimide. Compared with the unsized carbon fiber polyimide composites, the interfacial properties of the composites after the polyimide sizing treatment were significantly improved, with the interfacial shear strength (IFSS) increasing from 82.08 MPa to 136.27 MPa, the interlaminar shear strength (ILSS) increasing from 103.7 to 124.9 MPa, and the bending strength increasing from 2262.2 MPa to 2562.1 MPa. The sizing agent acts as a bridge between the carbon fiber and polyimide resin, with anchorage and bonding at the interface between the fiber and resin, which are beneficial for enhancing the interface performance of composites.

Mechanical, machinability and water absorption properties of novel kenaf fiber, glass fiber and graphene composites reinforced with epoxy

This paper aims to fabricate a novel kenaf fiber, glass fiber, graphene composite reinforced with epoxy, and to study its water absorption, mechanical and machining properties. Natural fiber composites seek numerous applications nowadays due to its high strength is to weight ratio, high impact resistance, thermal stability, and recyclability. The literature study on natural fiber composites indicates lack of research on Kenaf fibers reinforced with E-glass fibers in conjunction with 0.5% and 1.0% of graphene. Hence, this research focuses on Kenaf fiber with percentage composition of graphene was varied as 0.5%, and 1.0%, by weight of the holding matrix and with/without incorporation of glass fiber. Suitable surface modifications were done by treating natural fibres by 0.5% NaOH for better adhesion of fibre and epoxy resin. Sonication and Cetyl trimethyl ammonium bromide (CTAB) treatments were also done to realize the fine scattering of graphene in the epoxy matrix in order to achieve better mechanical behaviour. Moulds were prepared as per D-638 ASTM standards. The treated fibres were then arranged in the mould by the conventional hand layup technique. The main objectives of this study are to conduct tensile, flexural, Impact, water absorption, machinability, and FTIR test. Result shows that the incorporation of graphene in natural fiber composites showed an increase in tensile strength, flexural strength, and water absorption properties by 27.7%, 53%, and 15% on average, respectively. The composites used in this research find their use in potential applications such as defence, biomedical aids, automobiles, packaging, actuators, etc. These often generate great interest, whenever there is a demand for fabricating lightweight and high strength material.

NiCo2O4/reduced graphene oxide composite coated on modified commercial carbon cloth for long-cycle-life structural supercapacitors

Structural supercapacitors (SSCs) based on commercial carbon fiber cloth (CC) and resin can combine high specific capacitance with mechanical strength to achieve lightweight, making it an attractive option for portable devices, electric vehicles, and aerospace industries. Herein, a dually activated carbon cloth (ACC) is designed as the functional current collector, and then NiCo2O4/rGO (NCG) composite is synthesized and coated on the former to fabricate into the positive electrode. In the typical SSC, a positive electrode (NCG@ACC), a separator (glass fabric), and a negative electrode (AC@ACC) are bonded together by a particular ion-modified epoxy resin. The SSC (NCG-40@ACC) exhibits the specific capacitance of 10.8 F g−1, the highest energy density of 4.8 Wh kg−1 at the power density of 50 W kg−1, and the excellent cycle stability (the capacitance retention is 93.5 % after 4500 cycles). Mechano-electrochemical tests are also performed to verify the stable electrochemical behavior under bending (from 0° to 120°) and the good mechanical performance (tensile strength of 57.4 MPa and tensile modulus of 10.4 Gpa), respectively. The competitive mechano-electrochemical properties of NCG-40@ACC makes it a promising candidate for the development of structural supercapacitors.

Interfacial crystallization behavior and properties of T1100-grade carbon fiber reinforced PEEK composites

As a semi-crystalline resin, the crystallization behavior of Polyether ether ketone at the interface between carbon fiber and resin matrix profoundly affects the interfacial properties of carbon fiber-reinforced PEEK composite. Therefore, the research on the interfacial crystallization behavior of CF/PEEK composite is of great significance. Aiming at Chinese-made T1100-grade carbon fiber and PEEK resin matrix, the effects of cooling rate and sizing agent on the interfacial crystallization behavior of T1100-grade carbon fiber/PEEK were studied by POM and DSC, and the IFSS was tested by microdebond. The experimental results show that the increase of the cooling rate and the removal of the sizing agent can improve the nucleation ability of PEEK and promote the interfacial crystallization of PEEK. PEEK starts to form transcrystallization, when the nucleus density is increased to about 0.07/μm. The interfacial crystallization behavior has an effect on the interfacial properties. The IFSS increases with increasing cooling rate and removal of sizing agent.

Analysis of SAR mitigation implementing millimeter wave antenna with FSS-based absorber for 5 G application

In this article, an FSS-based absorber has been developed and utilized to mitigate the specific absorption rate of a millimeter-wave antenna loaded with an inter-digital capacitor (IDC) for 5 G applications. SAR mitigation of millimeter-wave antennas is one of the aspects to be considered for next-generation applications. The addition of a triple-band absorber operating at 28, 60, and 73 GHz reduces the SAR value by blocking radiation on the antenna's backside. This approach lowered the value of the SAR by 75 % and more through the targeted operating bands, diminished significantly the SAR distribution, and increased the antenna gain. In accordance with the Federal Communications Commission and International Commission on Non-Ionizing Radiation Protection (ICNIRP) regulations, a decrease in SAR values signify a decrement in radiation absorption by human tissue, thereby lowering the likelihood of health risks from electromagnetic radiation. Rogers RT-Duroid 5880 serves as the antenna's substrate, while epoxy resin fiber (FR-4) is used for the absorber. The investigation's findings in the constructed antenna sample with the incorporated absorber demonstrate that the modeled and observed results correspond well, demonstrating the viability and effectiveness of the unique design in SAR mitigation in millimeter wave bands.

Pengaruh Penambahan Serat Pohon Bambu Ampel (Bambusa Vulgaris) pada Komposit Hybrid untuk Material Bumper Kendaraan Bermotor

Technological developments continue to increase in line with the times, producing various innovations that provide benefits to society, especially in the material sector. The use of a mixture of natural and synthetic fibers in composites (hybrid) has produced a stronger material, which can function as an alternative material for car bumpers. This research was carried out with the aim of determining the values ​​of impact toughness, tensile strength, and failure patterns that occur in the fracture cross section of the specimen through macro photographs. In this research, a hybrid composite was formed by combining ampelous bamboo fiber, fiberglass, and polyester resin. Variations in volume fraction applied include: 5%:25%:70%, 10%:25%:65%, and 15%:25%:60%. The specimens were formed according to ASTM E23 standards for impact tests and ASTM D638 for tensile tests. The results of the impact and tensile tests showed that the lowest value of impact toughness was 0.0744 J/mm² and tensile stress was 120.29 MPa. Meanwhile, the highest value for impact toughness was 0.0986 J/mm² and the tensile stress value was 147.65 MPa. Macro photo analysis of the fracture cross section is categorized as splitting in multiple areas and the fracture cross section also shows debonding and fiber pull out after the fracture occurred.

Role of stable‐structural yarns and fabrics on the tensile and bending performance of carbon fiber resin composites

AbstractThe component yarns and fabrics effected the formability and stability of preforms, and finally determined the performance of corresponding composites. In this research, four typical fabric structures of carbon fiber resin composites (CFRC) were introduced to conduct the comparative investigation. The stability of component yarns in natural state and in fabrics have been discussed at mesoscopic scale, and the main methods to improve the structural stability of preforms were proposed. Composites with and without stable‐structural fibers and fabrics were manufactured by the modified curing process, and the yarn cross‐sections in specimens were analyzed. The tensile and bending performance of these composite specimens was comparatively conducted to discuss the influence of stable preforms on the elastic properties. The fracture mode and mechanism of specimens were illustrated in meso‐scale. The results depicted that yarns and fabrics with stable‐structural cross‐section could ensure a high fiber volume fraction, reducing the curvature of load‐bearing yarns, and effectively reduce the yarn curvature along bearing direction. The high interfacial bonding strength of composites with stable geometrical fabrics exhibited the excellent in‐plane mechanical properties, and presented the obvious brittle fracture characteristics when the fibers fully exert their load‐bearing capacity.Highlights Stable‐structural fibers result in the prominent performance of composites. Performance of composites with stable preforms show the low dispersion. Stable cross‐section of component yarns can enhance the stability of preforms. Low curvature yarns lead to brittle fracture characteristics of composites.

Exceptional damping of CFRPs: Unveiling the impact of carbon fiber surface treatments

A significant body of research has concentrated on augmenting the interfacial slippage between carbon fiber (CF) fabrics and resin to improve the damping properties of CF reinforced plastics (CFRPs). However, a critical but commonly overlooked issue lies in the fact that a higher number of mutual slippage interfaces may lead to potential debonding at the interface. This, in turn, not only influences mechanical properties but also escalates the risk of structural damage. In this study, three distinct modification methods are proposed to alter the surface characteristics of CFs, achieving simultaneous enhancement of the damping and mechanical properties of CFRPs. Specifically, the polymerization of dopamine on the CF surface results in CFRPs with a loss factor of 0.227 at 1 Hz, which is 180 % higher than the 0.081 of referenced CFRP. Additionally, using this modification method, the tensile modulus and strength of the CFRP are increased by about 11.3 % and 6.7 %, respectively. More importantly, the subtle relationships within the CFRPs interface are explored through the different surface modification methods. The interactions between surface wettability, specific surface area, roughness, and interfacial chemical bonding on the mechanical and damping properties are redefined and elucidated. This study demonstrates that surface modification can simultaneously enhance both the damping and mechanical properties of CFRPs, and a satisfactory balance of multiple enhancement effects can be achieved by adjusting the surface modification factors.

A Quad‐Port MIMO Antenna With Improved Isolation Developed by Colored Resin Fiber Material for Wideband Applications

ABSTRACTThe article explores a quad‐port compact (56 × 56 × 1.5 mm3) multiple‐input multiple‐output (MIMO) antenna developed on a colored resin fiber material encompassing enhanced isolation for wideband applications. The design antenna configuration incorporates four ground stubs positioned among antenna pairs on the upper section of the substrate and eight rectangular‐shaped ground slots to enhance antenna isolation. The antenna functions over a broad spectral range from 4.21 to 10.95 GHz, providing coverage for WLAN (5.15–5.35 GHz/5.725–5.825 GHz), C band uplink (5.925–6.425 GHz), downlink defense (7.2–7.7 GHz), and ITU band (8–8.5 GHz), with 88.91% fractional bandwidth. The antenna design ensures exceptional isolation, exceeding 21 dB among orthogonal antennas and 25 dB between oppositely placed antennas across the entire functioning bandwidth. Across the working band, the antenna showcases favorable diversity characteristics, including a lower envelope correlation coefficient (ECC < 0.085), higher diversity gain (DG > 9.95 dB), minimal channel capacity loss (< 0.39 bits/s/Hz), and negligible magnitude variation in mean effective gain among the antenna ports (< 0.1 dB). The acquired total active reflection (TARC) curve exhibits the antenna's robust resonance features over the application band and commendable time domain properties in the active spectral region. The findings of the simulation and measurements revealed a close alignment.

A comparison between the flexural strength of milled, conventional, and carbon fiber PMMA for interim implant supported fixed complete dentures: An In vitro study

Objectives: to investigate the flexural strength of three materials commonly used for interim implant-supported fixed complete dentures (ISFCDs): conventional heat cure PMMA, CAD/CAM milled PMMA, and carbon fiber-reinforced PMMA. Methods: Sixty specimens (n=60) divided equally into three groups (heat cure, milled, carbon fiber) were prepared. Samples were inspected to ensure absence of voids or irregularities and when required, minor adjustments were made to adjust the dimensions. The samples underwent thermocycling (5-55°C for 2500 cycles) and were then tested using a three-point bend test. Results: There was a statistically significant difference between heat cure PMMA and carbon fiber PMMA (p<0.001), between CAD-CAM resin and carbon fiber resin (p<0.001). There was no significant difference between CAD-CAM and conventional PMMA resin (p>0.05). Conclusions: as clinical implications, using carbon fiber is a viable treatment option for interim ISFCDs. Veneering the material with pink and white resin would improve the overall esthetics.

Comprehensive analysis of the effect of braiding angle on the wettability and mechanical properties of 3D braided carbon fiber fabric-reinforced composites

Fiber-reinforced composites are designed to enhance strength, stiffness, and lightweight properties. However, while the use of continuous fibers offer substantial performance benefits it presents challenges in achieving complex configurations. This study focused on evaluating the effects of different braiding angles on the mechanical properties of braided fabric-reinforced composites (B-CFRP). Continuous fiber tows were braided around a mandrel, with meticulous control over the key process parameters to ensure consistency. The composites were then processed using the Vacuum Assisted Resin Transfer Molding (VARTM) technique to achieve optimal impregnation of the resin. Mechanical properties, including tensile, flexural, compressive strength, interlaminar shear strength (ILSS), and impact strength, were performed to establish the relationship between resin impregnation and mechanical properties with different braid angles. Additionally, resin flow experiments and scanning electron microscopy (SEM) analysis were conducted to investigate how variations in braiding angle influence fiber arrangement, resin distribution, and fracture behavior. These insights aim to guide the design and manufacturing of high-performance composites.

Flexible and lightweight carbon fiber/silicone resin composites with the “soft-rigid” structural interface for thermostable and antistatic applications

To avoid a large difference in modulus between carbon fiber (CF) and silicone resin (SR) and unstable thermal properties, the “soft-rigid” structural interface is constructed by coating polydopamine-polyethyleneimine@octaphenyl-silsesquioxane (PDA-PEI@octaphenyl-POSS) on the fiber surface. The tensile strength of the CF-AE@3P/SR composite was 24.35 % higher than that of the unmodified CF/SR. The mechanism of mechanical enhancement revealed that the rigid layer with nanoparticles effectively deflected the crack and prolonged the path, and the hydrogen bonds and van der Waals forces helped disperse the stress concentration at the interface. The defects in the soft–rigid structural interface were reduced, and the decomposition of the fibers and composites was effectively inhibited, thereby increasing the heat transmission in the composites. After heating for 20 s on the heating plate at 200 °C, the surface temperature of the CF-AE@3P/SR composite was 155.4 °C, which is higher than that of the unmodified CF/SR (131.4 °C). Therefore, the thermal stability of the CF-AE@3P/SR composites was significantly improved compared to that of unmodified CF/SR after holding at 350 °C for 3 h. Surface resistance analysis showed that the soft–rigid modification maintained the antistatic properties of the composites at room and high temperatures. It was also found that the CF-AE@P/SR composites exhibited good flexibility, lightweight, and hardness for application in sealing and electronic components. This work provides ideas for forming a seamless transition and effective bonding between high-modulus carbon fibers and a low-modulus elastomer matrix, increasing the thermal stability and mechanical properties, and maintaining the flexibility, stiffness, lightweight, and antistatic properties of composites at high temperatures.

Post-Buckling Response of Carbon/Epoxy Laminates with Delamination under Quasi-Static Compression: Experiments and Numerical Simulations.

Delamination is a common type of damage in composite laminates that can significantly affect the integrity and stability of structural components. This study investigates the post-buckling behavior of carbon fiber-reinforced epoxy composite laminates with embedded delamination under quasi-static compression. Experimental tests were conducted using an electronic universal material testing machine to measure deformation and load-bearing capacity in the post-buckling stage. The specimens, prepared from T300 carbon fiber and TDE-85 epoxy resin prepreg, were subjected to axial compressive loads with delamination simulated by embedding Teflon films. Finite element analysis (FEA) was performed using ABAQUS software, incorporating a four-part model to simulate delaminated structures, with results validated against experimental data through comprehensive convergence analysis. The findings reveal that increasing delamination depth and length decrease overall stiffness, leading to an earlier onset of buckling. Structural instability was observed to vary with the size of delamination, while the post-buckling deformation mode consistently exhibited a half-wave pattern. This research underscores the critical impact of delamination on the structural integrity and load-bearing performance of composite laminates, providing essential insights for developing more effective design strategies and reliability assessments in engineering applications.

Fatigue analysis on flax-epoxy composites: insights and implications

This study investigates the performance of flax fiber and epoxy resin composites, focusing on fatigue testing, which is scarcely reported in the literature. Fatigue behavior is evaluated under full reverse bending loading conditions: R = −1. Apart of the definition of the classic S-N curve, the analysis deeply investigated the evolution of the hysteresis leaf generated during each cycle over the entire fatigue life. This approach allows evaluating interesting parameters such as the evolution of the loss factor and the apparent modulus over life, being these informations fundamental for practical application of natural-fiber composites in engineering applications.

4D printing of liquid crystal elastomer composites with continuous fiber reinforcement

Multifunctional composites have been continuously developed for a myriad of applications with remarkable adaptability to external stimuli and dynamic responsiveness. This study introduces a 4D printing method for liquid crystal elastomer (LCE) composites with continuous fibers and unveils their multifunctional actuation and exciting mechanical responses. During the printing process, the relative motion between the continuous fiber and LCE resin generates shear force to align mesogens and enable the monodomain state of the matrix materials. The printed composite lamina exhibits reversible folding deformations that are programmable by controlling printing parameters. With the incorporation of fiber reinforcement, the LCE composites not only demonstrate high actuation forces but also improved energy absorption and protection capabilities. Diverse shape-changing configurations of 4D composite structures can be achieved by tuning the printing pathway. Moreover, the incorporation of conductive fibers into the LCE matrix enables electrically induced shape morphing in the printed composites. Overall, this cost-effective 4D printing method is poised to serve as an accessible and influential approach when designing diverse applications of LCE composites, particularly in the realms of soft robotics, wearable electronics, artificial muscles, and beyond.

Mechanical Properties of Natural Composites: Hemp Fiber and Polypropylene Resin

Mechanical Properties of Natural Composites: Hemp Fiber and Polypropylene Resin

Comparison of Experimental and Numerical Investigation of Mono-Composite and Metal Leaf Spring

The automotive industry is increasingly focused on reducing vehicle weight, leading to the widespread adoption of composite materials with high strength-to-weight ratios in both aviation and automotive sectors. These materials are gradually replacing traditional options like steel. Leaf springs, one of the oldest and most common suspension components, continue to be widely used in vehicles. This study aims to replace conventional multi-leaf steel springs with mono-composite leaf springs while preserving the same load-carrying capacity and stiffness. Composite materials, such as glass fiber and epoxy resin, provide advantages including higher elastic strain energy storage, superior strength-to-weight ratios, and enhanced corrosion resistance compared to steel. Consequently, the weight of leaf springs can be reduced without sacrificing performance. The steel and mono-composite leaf springs were modeled using Catia software, and their performance was evaluated using ANSYS 15.0 software.

Surface modification of carbon fibres via plasma-activated water for mitigating burnout risk from direct plasma treatment

This study presents a novel plasma jet discharge device designed to indirectly treat carbon fibre materials with plasma-activated water. This innovative method effectively mitigates issues related to carbon fibre conduction and combustion, which are common challenges encountered when directly modifying fibres using a plasma jet. Specifically, the atmospheric composition is adjusted to modulate the active particles in the liquid phase. The experimental results demonstrate that this technique significantly increases the surface wettability of carbon fibres without damaging their structure. Under the conditions of argon/oxygen cascade discharge, oxygen-containing substances generate ionomers that activate the water, which in turn introduces oxygen-containing groups (e.g., C−O, C=O, O−C=O) onto the carbon fibre surface. These groups catalyse monomer polymerisation on the material surface, which increases the wettability of the carbon fibres, as evidenced by a significant reduction in the water contact angle from 80.12° to 55.31°. This in turn improves the bonding strength with epoxy resin and slightly increases the monofilament strength. Furthermore, composites produced by this method exhibit 21% higher interlaminar shear strength than the untreated sample and an increased O/C ratio of up to 24.55%. In summary, these findings provide a valuable theoretical basis for enhancing the surface properties of carbon fibre composites through plasma–liquid interactions and open new possibilities for high-performance carbon fibre–resin matrix composites.

Damage characterisation of GFRP composites based on clustering acoustic emission events utilizing single-failure-cause tests as reference

A new method to identify causes of fracture in composites based on acoustic emission (AE) and clusterization of AE data based on reference datasets is presented within the manuscript. Acoustic Emission (AE) is a widely used non-destructive method for fracture analysis, but data due to their multidimensionality are not easy to analyze especially if the acoustic events appear simultaneously and have similar parameters even if they are an effect of different failure mechanisms. In this research, we utilize an unsupervised learning algorithm besides the simplest K-means, through fuzzy c-means to Gaussian Mixture Model (GMM) and spectral clustering to investigate the dataset obtained from the three-point bending test manufactured by us composite. The analysis is preceded by data curation, feature determination (Laplacian score) and the best number of cluster investigations (DB index, Caliński-Harabasz score, and Silhouette method) To enable interpretation of the clustering we run an additional three groups of tests covering fibre breakage (two methods), resin fracture (in tension and in compression) and delamination (DCB test) creating reference datasets. These datasets were statistically analyzed and kernel density estimators were generated for each AE feature as well as amplitude-frequency characteristics. Clusters obtained for the main dataset were then assigned to particular causes of failure by comparing them with the reference dataset. It was found that clusters generated using spectral clustering were the most realistic ones, as it was possible to assign the cause of failure to them.

Rehabilitation and reinforcement of cracked pavements using crack sealers and composite patches

Cracking is a significant concern for pavements and should be appropriately treated during road, highway, and runway rehabilitation. This study investigates the behavior of asphaltic materials under tensile and shear loading modes in intact, fractured, and repaired conditions. With this aim, several methods and materials are utilized for repairs, such as poring adhesive into the crack (using bitumen, neat epoxy resin, and polymer concrete adhesives) and patching the crack with textile (by glass fiber and epoxy resin or bitumen). These tests were conducted at +10 °C, with a three-point bending loading configuration, the same as the actual loading configuration of pavements. Criteria such as failure load, failure work, and post-failure work, as well as failure patterns, were assessed to assess the effectiveness of repairs. Numerical analysis was also performed, and a constitutive model was presented. The ultimate tensile capacity of the cracked specimen is measured at 63 % lower than the intact condition (778 N). The ultimate tensile load of the bitumen-repaired specimen is higher than that of the cracked specimen, but it is still 11 % lower than that of the intact condition. The ultimate tensile capacity of epoxy resin repaired and polymer concrete repaired specimens are 88 % and 79 % higher than the intact specimen (about 1400 N). The ultimate tensile load of the fabric patch reinforced specimen that used bitumen as the adhesive is 38 % higher than the intact specimen (1075 N), while for the case of using the epoxy resin adhesive, this value is 258 % (2788 N). Observations of tensile failure patterns show that, because bitumen is viscoelastic, failure in bitumen-repaired specimens happens in bitumen necking mode and starts at the repaired crack tip. In other cases, the failure occurred far from the pre-crack plane.