Properties Of Carbon Fibers Research Articles

Improved interfacial properties of carbon fiber reinforced epoxy resin composite by in‐situ self‐assembled mental‐phenolic networks

AbstractThe chemical modification of carbon fiber surface often uses toxic reagents and harsh reaction conditions, while the preparation process of metal‐phenol networks (MPNs) is simple, rapid, non‐toxic and harmless, which provides a direction for alleviating environmental problems. In this study, tannic acid (TA) was coordinated with Fe3+ to form MPNs, which was coated on the surface of carbon fibers through π‐π interaction. The results indicated that oxygen functionalities on the surface of the MPN coating can facilitate better adhesion between the carbon fiber and the epoxy resin, when the molar ratio of TA to Fe3+ is 1:3 and the pH is 4, the interlaminar shear strength (ILSS) performance of the composite material reaches its optimal level. In addition, a green and non‐destructive method is provided for the surface modification of carbon fiber, which can effectively optimize the interfacial properties of carbon fiber reinforced polymer (CFRP) composites.

Effect of surface treatment on interface properties of carbon fiber reinforced PA6 composites during overmolding

AbstractCarbon fiber‐reinforced thermoplastic composites have the advantages of lightweight and high strength and have broad application prospects in automotive lightweighting. This study uses the Overmolding process to mold carbon fiber‐reinforced nylon 6 composite materials. By using laser surface treatment and preheating technology, the interfacial bonding performance of the composite material is emphasized. By optimizing the embedding temperature, it was observed that the in‐plane shear strength increased by 13 times to 70 MPa, and the tensile strength increased by 10 times to 44 MPa. Similarly, by adjusting the melting temperature, the in‐plane shear strength was significantly improved, and the mechanical interlock and interfacial bonding were effectively enhanced by laser surface treatment, achieving the same effect as embedding preheating. By establishing a finite element model, the in‐plane tensile and in‐plane shear at the interface were accurately simulated, and the progressive failure process of the interface layer was successfully predicted.Highlights Laser energy density strengthens the overmolding interface. Optimizing insert, mold, and melt temperatures enhances interface bonding. Shear and tensile tests reveal differences in interface failure behavior. Finite element model accurately simulates overmolding interface failure. Laser treatment and temperature control are key to stronger interfaces.

Research progress on high-temperature properties of carbon fiber reinforced polymer composites for cables

Carbon fiber reinforced polymer composites (CFRP) cable has advantages of lightweight, high strength, and excellent durability, providing a new materials for cables and bringing out potential breakthrough in spanning capacity of structures. At present, CFRP cable has already been applied in some engineering bridges. The fire resistance performance of CFRP cable is critical for ensuring structure safety when suffering accidental fire disaster, and clarifying mechanical performance deterioration and failure mechanism of CFRP cable at elevated temperature is fundamental for research of its fire resistance. This paper summarizes current research progress on high-temperature properties of CFRP cable from two levels, including epoxy resin matrix and CFRP composites. Firstly, at resin matrix level, mechanical properties of epoxy resin and its degradation at elevated temperatures are reviewed and analysed, and potential ways to improve high-temperature performance of epoxy resin are suggested. Secondly, at CFRP composites level, high-temperature properties test methods and mechanical performance of CFRP composites in longitudinal direction and transverse direction at elevated temperatures are summarized and discussed. In addition, research shortage of high-temperature properties of CFRP cable is summarized, and corresponding further research is recommended.

CFRTP single-lap adhesive bonding and its mechanical performance enhanced by laser surface treatment: Finite element simulation and experimental validation

The outstanding mechanical properties of carbon fiber reinforced thermoplastic polymer (CFRTP) have led to its widespread application in many industrial sectors. In response to the engineering challenge of repairing large non-critical CFRTP structural components in situ, an infrared fiber laser surface cleaning technology is proposed to treat the bonding interface and enhance the tensile strength of polypropylene (PP)-based CFRTP single-lap bonded joints. Specifically, through single-factor and orthogonal experiments, the impact of different process parameters on the properties of the bonded joints was identified first. Then, online temperature monitoring was performed to elucidate the laser treatment mechanism of the CFRTP sample interface. Surface morphology of the laser-treated samples further indicates that when the temperature of the sample surface surpasses the resin decomposition temperature with extended holding time, the resin could be removed from the surface more thoroughly. Additionally, a novel three-dimensional woven finite element (FE) model, accounting for anisotropic heat transfer, was established to predict the surface temperature and cleaning quality of CFRTP. The FE model incorporates the anisotropic heat transfer characteristics of carbon fibers, thus accurately simulating the heat transfer behaviors between carbon fibers and the resin matrix. The laser ablation mechanism is elucidated by examining the surface ablation morphologies and peak surface temperatures. A comparison between experimental results and FE simulations demonstrated a notable coherence in the trend of surface morphology variations, with discrepancies in peak surface temperatures ranging from 3.29 % to 24.63 %. The experimental tests proved that the shear strength of single-lap bonded joints reaches its maximum value when the laser power is 35 W, the scanning speed is 2500 mm/s, and the number of scans is four. The enhancement of the mechanical properties of bonded joints can be attributed to the improved wettability and higher surface free energy of the laser-treated samples.

Comprehensive evaluation of interfacial interactions optimization for CF reinforced high-performance thermoplastic composites by electrochemical deposition of conjugated polymers

The mechanical properties of carbon fiber (CF) reinforced high-performance thermoplastic composites are significantly compromised due to inadequate interface bonding between CF and matrix. In this study, electrochemical polymerization techniques were employed to modify CFs with polypyrrole (PPy), poly-aniline (PANI), and poly-o-phenylenediamine (PoPd), to systematically investigate the impact of conjugated polymers on the interfacial properties of CF/copoly (phthalazinone ether sulfone ketone)s (PPESK) composites through a combination of experimental and molecular dynamics (MD) approaches. The findings revealed distinct differences among these conjugated polymers in terms of their effects on both IFSS and ILSS for CF/PPESK composites. Among all tested laminates, PoPd@CF-60s/PPESK exhibited the highest IFSS, ILSS and flexural strength values of 39.8 MPa, 75.6 MPa, and 1494 MPa, respectively, 94.1 %, 20.6 %, and 47.6 % higher than those of CF-desized/PPESK, without compromising CFs strength and thermal resistance of CF/PPESK composites. MD simulations combined with fracture morphology analysis confirmed that compatibility between conjugated polymers and matrix played a pivotal role in enhancing interface properties for CF/PPESK composites. Furthermore, the AFM outcomes demonstrated that the PoPd layer could serve as the modulus transition layer between the CF phase and the PPESK phase, which effectively enhancing the load transfer efficiency between the two phases under external forces. To summarize, this work presents a straightforward yet non-destructive approach that effectively enhances the interface strength within advanced CF reinforced high performance thermoplastic polymer composites (CFRHPTPs).

Effect of fiber surface treatment with silane coupling agents and carbon nanotubes on mechanical properties of carbon fiber reinforced polyamide 6 composites

Effect of fiber surface treatment with silane coupling agents and carbon nanotubes on mechanical properties of carbon fiber reinforced polyamide 6 composites

Carbon fibres: Effect of various thermo-oxidative environments on structural and performance damage, both alone and in composites

This study examines the effects of heat and fire on the physical, mechanical and electrical properties of carbon fibre and those in carbon fibre reinforced composites (CFRCs). Carbon fibres were exposed to controlled heating (thermogravimetric analysis (TGA) and a tube furnace) in inert and air (oxygenated) environments and simulated fire (cone calorimetry at 35–75 kW m−2 and jet fire (propane burner) of 116 kW m−2) atmospheres. In inert atmospheres there was a minimal effect on the properties of carbon fibres, but in an oxygenated environment, significant oxidation began at temperatures ≥550 °C, resulting in a reduction in fibre diameter, which reduced further with increasing temperature and exposure duration. Tensile strength and electrical conductivity of carbon fibre decreased with reduction in fibre diameter. CFRCs exposed to 75 kW m−2 in a cone calorimeter and direct flame in a propane burner (116 kW m−2) showed varying degrees of oxidation in CFRC plies, with surface ply fibres experiencing more oxidation and consequent reductions in fibre diameter and tensile properties compared to fibres in underlying plies, where oxidation was limited due to restricted oxygen availability. Fibres exposed to the propane burner exhibited notable damage, including pitting and internal oxidation. Despite this, the overall electrical properties of residual carbon fibres did not significantly decrease, indicating that they still pose an electrical hazard if exposed during a high heat or fire event.

Enhanced mechanical property, high-temperature oxidation and ablation resistance of carbon fiber/phenolic composites reinforced by attapulgite

To meet the thermal protection and load-bearing requirements of ultra-high-speed vehicles, it is urgent to improve the ablation resistance, high-temperature oxidation resistance and mechanical properties of carbon fiber/ boron phenolic resin (CF/BPR) composites simultaneously. Herein, polyhedral oligomeric silsesquioxane-modified attapulgite (ASP) with abundant porous structure was successfully introduced into the CF/BPR (CF/ASPBPR). The co-effect of ceramization, high infrared emissivity, and low thermal conductivity endowed the CF/ASPBPR with desirable ablation resistance, where the linear ablation rate and mass ablation rate reduced to 0.038 mm/s and 0.035 g/s, respectively. Meanwhile, due to the high thermal stability and energy dissipation of ASP, the CF/ASPBPR also presented the interlaminar shear strength of 35.40 and 9.79 MPa before and after high-temperature treatment, which were 24 % and 63 % higher than that of CF/BPR, respectively. This study provides a promising pathway for preparing advanced thermal protection materials that can adapt to severe mechanical spalling and thermochemical erosion environments.

Increasing softening point of isotropic spinnable asphalt by two-step preparation from ethylene tar residue modified with bio tar residue

Carbon fiber prepared from asphalt may be a critical type of low-weight chemical material of excellent mechanical performances. Here, an isotropic spinnable asphalt (EBA) was prepared from ethylene tar residue (ETR) by a two-step method of bio tar residue (BTR) through co-polymerization-air blowing, and isotropic asphalt carbon fibers were prepared from the product asphalt. The main types of molecules contained in the two feedstocks were determined by 1H NMR and LDI-TOF MS analyses. The co-polymerization behavior and thermal stability of the asphalt blends were analyzed using polarized light microscopy and thermogravimetric analyzer, respectively. Finally, the morphology and mechanical properties of carbon fibers made from EBA were evaluated by scanning electron microscope and universal testing machine. The results show that BTR contains much more oxygen-containing functional groups and unique long-chain sawtooth molecular structure; the former can promote the reactivity of the co-polymerization reaction, and the latter can limit the formation of large-plane cyclic aromatic hydrocarbon polymers due to the spatial resistance effect to greatly reduce the content of the mesophase. The softening point of the product asphalt shows a tendency of increasing and then decreasing with the increase of the proportion of BTR in the raw material mixture, and a reaction mechanism based on linear and bulky molecules is proposed to explain it by analogy with the structure of macromolecules. Consequently, the EBA made from a mixture of ETR and BTR at ideal moderate proportions has excellent performance in terms of softening point and mesophase content than ETRO made from ETR alone, and the carbon fiber made has a high tensile strength of 1.82 GPa with an elastic modulus of 38.9 GPa, which has reached the level of high tensile strength carbon fiber. Therefore, the use of inexpensive renewable energy bio-asphalt in the modification of heavy oil to obtain high softening point isotropic asphalt for preparing isotropic carbon fiber with excellent properties is achievable.

Influence of stacking sequence on flexural properties of hybrid carbon fibre reinforced polymer laminates

This paper presents a numerical investigation of the influence of the stacking sequence and fibre variation of the plies on the flexural properties of carbon fibre-reinforced polymer laminates. The numerical approach utilised a three-point flexural test to evaluate different quasi-isotropic stacking sequences. It also analysed attempts to reinforce failure-prone plies only using a stronger prepreg material to reduce the cost of the laminate. The results were validated by conducting a cantilever bending test and compared with calculations based on classical lamination theory. The beam deflection, normal stress per ply, and the Puck failure criterion inverse reverse factor per ply were used for evaluation and result comparison. The results showed that the quasi-isotropic stacking sequence [0/90/+45/−45]s is the most suitable for beam applications. Replacement of the outer plies of the composite laminate by a stronger ply material made the hybrid laminate performance almost identical to a pure composite laminate consisting of stronger material only.

Effect of acid soak treatment of the precursor on the structure and properties of polypropylene-based carbon fibers

Polyolefin fibers have received wide attention as the precursor for low-cost carbon fiber, and cross-linking of linear polyolefin by strong acid has been proven to be an effective way to stabilize the precursor fiber prior to carbonization. However, the conventional temperature used in sulfonation process is too high and could result in severe decomposition of the linear chain of the polymer, which further deteriorated the mechanical properties of the as-prepared carbon fiber. Thus, reducing the duration of sulfonation process operated at high temperature may alleviate the degradation behavior, conferring the polyolefin-based carbon fibers with better performance. In this paper, polypropylene (PP) fibers were soaked in sulfuric acid at 50 °C–90 °C, before the conventional preparation protocol of PP-based carbon fiber. The structural evolution from PP to carbon fiber were characterized by Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Raman spectroscopy. The mechanical and conductive properties of carbonized fibers where further measured. The results showed that the soak in sulfuric acid resulted in swelling of PP fibers in diameter direction, as well as reducing the crystallinity of the fibers, both of which were physical transformation, and could be easily controlled by soak temperature. The subsequent sulfonation at conventional temperature was fastened for the soaked PP fibers, and the duration of sufficient sulfonation were almost reduced by half. The obtained carbon fibers exhibited better thermal conductivity and mechanical properties, which were enhanced by 25 % and 40 %, respectively, compared with that without soak pretreatment.

Development of a novel characterization model for innovative bionic helical carbon fiber tows

The design of bionic helical structures significantly enhances load-bearing capacity and impact resistance, demonstrating great potential for mechanical property improvement. However, there is still a lack of precise characterization models for the helical structures of carbon fibers, which constrains their potential in engineering applications. This paper successfully fabricated helical carbon fiber tows using a carbon fiber twisting technique and introduced a novel intersecting circular cross-section model to thoroughly investigate the influence of the helical structure on the mechanical properties of carbon fiber tows. Tensile test results show that at a twist angle of 5°, the helical structure increases the tensile strength and fracture toughness of carbon fiber tows by 13.6% and 34.3%, respectively. Additionally, the introduction of complex structures such as helices significantly influences the material’s modulus, and precise modulus prediction is crucial for material optimization and practical application. Based on the newly proposed model, a modulus prediction model is developed, demonstrating higher predictive accuracy than traditional models with a prediction error of 2.8%. Finite element simulations further validate the practicality and superiority of the intersecting circular cross-section model. Compared to traditional models, the predictions of the novel model are closer to experimental data, with a prediction error below 2%, emphasizing the significant impact of microstructures on macroscopic properties and offering a new perspective for modeling complex material systems. These findings provide crucial theoretical and methodological support for the design and performance optimization of carbon fiber materials.

Effect of hollow glass microspheres on transverse properties of carbon fiber reinforced epoxy composites

AbstractHollow glass microsphere (HGM)—based composites are gaining popularity in materials research due to their ability in altering material characteristics drastically. The current study investigates HGMs filled carbon fiber reinforced epoxy (CE) composites on transverse properties, aiming for aerospace and defense applications mainly in composite pressure vessels. Unidirectional laminates of Carbon/Epoxy with varying HGM percentages (0.2, 0.4, 0.6, 0.8, 1.0 wt. %) were wounded onto a flat‐plate mandrel using a 4‐axis filament winder, along with a baseline sample without HGM for comparison. The glass transition temperature (Tg) and thermal stability were analyzed by carrying out dynamic mechanical analysis and thermogravimetric analysis. The fracture mechanism of the samples loaded under tension was investigated using FESEM. Experimental results indicate reduction in density with increase in HGM content, up to 0.4% HGM there is increase in transverse tensile strength of 25% compared to baseline and further increase in HGM content, decrease trend is observed. 30% decrease in transverse compressive strength is observed compared from baseline to 1.0 wt. % of HGM. No significant change was noticed in the thermal stability and Tg on introduction of HGM. Microscopy images of fractured samples revealed effective physical interaction and dispersion of the HGM within the matrix.Highlights Transverse mechanical properties are tested to know the influence of HGM filler on filament wound composites. Density of the composite decreases with increase in HGM content. Thermal stability and Tg shows less change on introduction of HGM in composites.

Effect of aromatization degree of mesophase pitch on cracks and mechanical properties of mesophase pitch-based carbon fibers

The aromatization degree of MP is closely related to the orientation of carbon fibers, which determines their properties. To investigate the effect of the aromatization degree of MP on the properties of carbon fibers, this study prepared MP with varying aromatization degrees using the self-pressurization/N2-blowing two-stage thermal condensation method with refined coal tar pitch as raw material. Mesophase pitch-based carbon fibers (MPCFs) were obtained through melt spinning, pre-oxidation, and carbonization processes. Results show that the C/H atomic ratio rises from 2.067 to 2.318 as the aromatization degree of MP increases. After carbonization at 1300 ℃, the microcrystalline structure of MPCFs becomes ordered, with obvious axial radiation in the cross-section. The carbon layers in MPCFs are tightly stacked in parallel, significantly improving tensile strength and modulus. When the C/H atomic ratio of MP exceeds 2.262, the resulting MPCFs exhibit a maximum tensile strength of 1389 MPa and a maximum tensile modulus of 167 GPa. However, when the C/H atomic ratio of MP exceeds 2.318, the excessive aromatization degree makes the MPCFs structure prone to cracking due to circumferential volume shrinkage, and the appearance of cracks reduces the tensile strength of MPCFs.

Impact of plasma-modified pretreatment on the tensile properties of carbon fiber-reinforced epoxy composites

Abstract Low-temperature jet plasma modification technology is a surface treatment method designed to enhance the surface properties of materials without causing severe thermal damage. This technique modifies surface characteristics by creating plasma and utilizing ions and reactive groups within the plasma to chemically interact with the material’s surface. In this study, surface modification of carbon fibers was carried out by using low-temperature jet mixed oxygen plasma technology at treatment speeds of 25 mm/s, 50 mm/s, 100 mm/s, and 200 mm/s. Following the modification process, carbon fiber-reinforced epoxy composites were fabricated by using a hand-lay-up technique. Subsequently, the tensile properties of the carbon fiber composites were tested to evaluate the impact of the plasma treatment on their mechanical performance. The experimental results demonstrated a significant enhancement in the tensile properties of the composites when the carbon fibers were pretreated at a rate of 50 mm/s. This enhancement was evidenced by an impressive increase of 82.38% in tensile strength and 30.96% in tensile modulus compared to untreated samples. This signifies that low-temperature plasma treatment has a beneficial effect on enhancing the surface properties of carbon fibers and improving the performance of composites. This finding provides substantial support for the extensive application of carbon fiber composites.

Effect of halloysite addition on the dynamic mechanical and tribological properties of carbon and glass fiber reinforced hybrid composites

Composite materials have become prominent in the aerospace, automotive, wind energy, biomedical, and machine tool industries. This has demanded the evaluation of the dynamic mechanical and tribological behaviour of composites to understand their performance and ensure their reliability and safety in varied operating conditions. In this study, the effect of halloysite nano-clay addition on the dynamic mechanical and tribological properties of the carbon/glass hybrid composites was investigated. The composites were produced with the vacuum assisted resin infusion process. by varying the content of halloysite nano-clay (1, 3, and 5 wt%). The dynamic mechanical properties of the manufactured composites were examined at temperatures ranging from 30 °C to 180 °C. The tribological properties of the specimens were assessed by varying the applied load (10, 20, and 30 N), sliding speed (1.5, 3, and 4.5 m/s) and sliding distance (500, 1000, and 1500 m). Box-Behnken design was utilized to optimize the number of experiments. The results showed that the halloysite-added samples had better dynamic mechanical and tribological properties than the carbon/glass hybrid composites. Especially, hybrid composites containing 3 wt% halloysite outperformed the other composites investigated. A scanning electron microscope (SEM) was used to examine the worn surface and wreckage in the investigated composite specimens.

Simulation analysis of cryogenic mechanical properties of carbon fiber reinforced silicon-containing epoxy resin composite

The use of carbon fiber-reinforced resin matrix composites instead of metals to manufacture cryogenic propellant tanks for spacecrafts is a development trend in the world aerospace industry. Cryogenic mechanical properties of the composites should be investigated in detail due to that the ultra-low temperature environment may cause micro cracks in the composites, leading to propellant leakage. In the present study, cryogenic tensile properties of a carbon fiber reinforced silicon-containing epoxy resin aomposite are investigated using experimental and numerical simulation methods. A silicon-containing epoxy resin with excellent cryogenic mechanical properties is developed by introducing a synthesized organic silicon polymer epoxidized polysiloxane and Nano-SiO2 into bisphenol F type epoxy resin. The tensile strength and modulus of the silicon-containing epoxy resin at −180 °C are 202.63 MPa and 7.81 GPa, which are 16.71% and 3.03% higher than those of bisphenol F type epoxy resin. The tensile strength of the silicon-containing epoxy resin at −180 °C is increased by 107.7% compared to that at room temperature, and the modulus at −180 °C is nearly twice that at room temperature. The carbon fiber reinforced silicon-containing epoxy resin composite is prepared by vacuum injection molding. The finite element model for the representative volume element of the composite unidirectional plate is established. The random sequence expansion method is used to randomly distribute the carbon fibers and simulate the thermal residual stress, the elastic performance, and the damage of the composite at cryogenic environments. Through comparison, it is found that the simulation results are in good agreement with the experimental results. The simulation reliability for cryogenic mechanical properties of carbon fiber reinforced resin matrix composites is verified. It is expected to provide a reference for the analysis and evaluation of cryogenic mechanical properties of composite tanks.

Mechanical Properties of Carbon Fiber Reinforced Materials for 3D Printing of Ankle Foot Orthoses

Mechanical Properties of Carbon Fiber Reinforced Materials for 3D Printing of Ankle Foot Orthoses

Study on the mechanical and electrical conductivity properties of waste short carbon fibers concrete and the establishment of conductivity models

The properties of waste short carbon fibers (WSCFs) were firstly characterized in this paper, and the effects of WSCFs with different lengths and contents on the mechanical properties and electrical conductivity of concrete were mainly investigated. Conductive model for WSCFs concrete was established based on the core-shell structure. The results revealed that, in comparison to virgin carbon fibers, WSCFs contained a small amount of resin, and the microscopic surface of WSCFs was smoother, but the content of C elements was low, the wettability and graphitization were poorer. The compressive strength of concrete did not significantly change after being mixed with WSCFs. Compared with the control group (0 %), only when the WSCFs content was 1 %, the compressive strength was slightly improved. The splitting tensile strength decreased as the length of WSCFs increased at the same content. When the length of WSCFs was 10 mm or 20 mm, the resistivity of concrete decreased by 86.0 % and 90.3 %, respectively, at 0.5 % content (28 d). As curing age increased, the free water inside the concrete decreased, and fibers were wrapped by hydration products, resulting in an increase of resistivity. Increasing the length of WSCFs from 10 mm to 20 mm effectively increased the probability of fiber overlap, constructing a more connected conductive network and reducing the conductive threshold of concrete from 0.5 % to 0.4 %. The established conductivity model for WSCFs concrete exhibited high calculation accuracy. The calculation results showed that for WSCFs with a length ranging from 10 mm to 50 mm, the concrete resistivity was very close and fluctuated less for the WSCFs content greater than 0.5 %.

Effects of carbon nanomaterials on the interfacial properties of carbon fiber reinforced epoxy resin composite

AbstractThe surface of carbon fiber is treated with sizing agent containing hydroxylated carbon nanotubes, fullerenols, and graphene oxide, respectively. The effects of carbon nanomaterials and their structures on the surface properties of carbon fiber, the interfacial properties and the mechanical properties of carbon fiber/epoxy composites are investigated. All three types of carbon nanomaterial can improve the interfacial bonding strength and modulus, thereby enhancing the interlaminar shear strength (ILSS) of composites. Moreover, the ILSS increases with the increase of interfacial bonding strength, due to the roughness and the number of active groups. Compared with the composite without carbon nanomaterials, the interfacial bonding strength of the three nanoparticle‐modified composites increased by 14%, 5% and 4%, the modulus increased by 10%, 26%, and 9%, and the ILSS increased by 14%, 8%, and 7%, respectively. The interfacial bonding strength has a more significant impact on the ILSS than the interfacial modulus.Highlights CNTs, graphene oxide and fullerenols regulate the surface characteristics of carbon fibers. The influence of carbon nanomaterials on the interfacial properties of composites. The relationship between the fiber surface, the interface and the composites.