Additive manufacturing has new revolutionary potential for carbon fiber‐reinforced polymers (CFRPs). Additive manufacturing of CFRPs combines the advantages of additive manufacturing such as ...customization, minimal wastage, low cost, fast prototyping and rapid manufacturing with high specific strength of carbon fiber. This article delivers a comprehensive review of additive manufacturing of short and continuous CFRPs. The article presents insight into different additive manufacturing techniques with an overview of commercially available methods for manufacturing short and continuous CFRPs. This review also includes mechanical characterization and analytical techniques discussed in the literature for CFRPs. The robust applications of short and continuous CFRPs in biomedical, electronics, and aerospace would highlight the importance of research and development in this field. In the end, drawbacks, recent innovations, and the future research directions underline the gap between research and commercialization of additive manufacturing of short and continuous CFRPs.
The tailor-folding method is proposed to make an all-composite sandwich panel with a carbon fiber reinforced polymer (CFRP) hexagon honeycomb core. Using this method, a CFRP honeycomb core with ...continuous fibers is fabricated automatically from a continuous plain woven prepreg to reinforce the constraints between adjacent cell walls. The analytical expressions were derived for predicting the stiffness and strength of the CFRP hexagon honeycomb sandwich panels for out-of-plane compression and shear loadings. The corresponding failure mechanism maps were also constructed for estimating the dominant failure mode of the honeycomb core, including elastic buckling and fracture under out-of-plane compressive and shear loadings. Selected geometries of the sandwich panels were tested to illustrate these failure modes, with a reasonable agreement between the analytical predictions and experiments. It was observed that the CFRP hexagon honeycomb exhibit good specific energy absorption ability. The tailor-folding method has the potential to provide new opportunities for lightweight multifunctional honeycombs.
Carbon fiber is an oft-referenced material that serves as a means to remove mass from large transport infrastructure. Carbon fiber composites, typically plastics reinforced with the carbon fibers, ...are key materials in the 21st century and have already had a significant impact on reducing CO2 emissions. Though, as with any composite material, the interface where each component meets, in this case the fiber and plastic, is critical to the overall performance. This text summarizes recent efforts to manipulate and optimize the interfacial interaction between these dissimilar materials to improve overall performance.
An effective method for bonding carbon nanotubes (CNTs) onto carbon fibers (CFs) surface via layer-by-layer (LBL) grafting method is reported here. The CNTs have been chemically grafted as confirmed ...by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) indicates that this LBL method can increase the dispersion quality of the CNTs on CF surface. The polarity, wettability and roughness of the CFs have been significantly increased after the CNTs modifying. The interfacial shear strength (IFSS) and impact strength test suggest that the hierarchical structure can result in a remarkable improvement for the interfacial properties. The results also indicate that this LBL method is a promising technique to modify CFs with the high interfacial performance.
Machining of carbon fiber-reinforced polymer (CFRP) with less damage remains to be a challenge because of anisotropy and inhomogeneity issues. Flood cooling will reduce the mechanical properties of ...CFRPs due to its hygroscopicity, however, dry grinding will result in thermal damage and deterioration of surface integrity, which cause it not suitable in aeroengine and aerostructure applications. Aiming to resolve the above gaps, the grinding mechanics for a single grain of CFRPs involving CNT nano-lubricant minimum quantity lubrication (MQL) is explored. To reveal the various fundamental mechanisms in machining CFRP of special transversal grinding and lubrication conditions, four sub-models were developed based on the unique geometries of grain and fiber in contact due to the random fiber arrangements and grain edge shapes under different undeformed chip thicknesses. Specifically, the models account ⅰ) the contact force model between the grain tip and fibers, ⅱ) the local contact stress model of elliptical region between the spherical grain edge and cylindrical fiber, ⅲ) the tensile fracture force model of single fiber regarded as an bending beam fixed at both ends and constrained on the elastic foundation, and ⅳ) the extrusion and shearing force model on the cut fiber section at the grinding groove. Furthermore, the grinding force model is obtained by integrating these sub-models, in which the grain-fiber friction coefficient and grinding mechanics are accurately introduced. Finally, the model is numerically simulated and the trend of force along the entire grinding arc length is obtained. Experimental verifications demonstrate the approach for predicting the grinding force have acceptable accuracy and can successfully capture the mechanics of CFRPs. The model reveals that the tensile fracture force of single fiber has the most contributions to the grinding force.
Environmental economics is accelerating the urgency to develop recycling technologies for the ever-growing quantity of discarded carbon fiber reinforced polymer composites (CFRCs). Herein, an ...imine-containing epoxy hardener (ICH) was synthesized by condensation of lignin-derived vanillin and methylcyclohexanediamine. The epoxy resin (vitrimer) cured by ICH has sufficient glass transition temperature (≥131 °C), tensile strength (≥82 MPa) and solvent resistance. The incorporated dynamic imine bonds allow the epoxy resin to be reprocessable and degradable. The reprocessed resin has slightly increased glass transition temperature (Tg) and around 90% retention rate of tensile strength. Besides, the imine-containing epoxy resin can be chemically recycled in a closed-loop manner by two different methods. Among them, one recycled epoxy resin almost obtains a full recovery in terms of tensile strength and Tg. The CFRCs based on the ICH cured epoxy resin exhibit comparable flexural properties compared to those based on conventional epoxy resins. The vitrimer feature of the ICH cured epoxy resin enables the CFRCs to be repairable. Especially, 92% strength recovery is achieved for the repaired CFRCs after interlaminar shear failure. Furthermore, nondestructive carbon fibers are recovered from CFRCs by degrading the matrix resin in an amine solvent, and the degradation products can be re-used to prepare new epoxy resins, thus achieving a full recycling process for CFRCs. We believe the findings in this work would provide a promising solution for the recycling of CFRCs.
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•An imine-containing epoxy resin with high performance and versatile recyclability.•The recycled epoxy resins show high performance retention rate.•Closed-loop recycling of carbon fiber reinforced epoxy composites.
The lack of ductility is the main concern in the use of carbon fiber-reinforced polymer (CFRP) reinforcement as prestressing tendon in concrete members. To address this concern, a partially bonded ...concept has been proposed. In this approach, CFRP tendons are intentionally debondedfrom the concrete in the middle region of the prestressed concrete beam, -while remaining bonded at each end. In this study, eight post-tensioned beams, including five beams -with CFRP tendons and three beams with steel tendons, are tested under cyclic loading. Three bond conditions, including fully bonded, partially bonded, and fully unbonded, are considered. The results indicate that increasing the unbonded length of the tendon changed the failure mode from CFRP rupture to concrete crushing. There is a trend that the flexural capacity decreased with the increase of the unbonded length. The displacement ductility (micro) of partially bonded CFRP prestressed beams ranged from 5.38 to 5.70, which is significantly higher than that of the fully bonded beam (micro = 2.83) and slightly lower than that of the fully unbonded beam (micro = 6.10). Finally, by introducing a relative bond length coefficient into the ultimate tensile stress equation for internally unbonded tendons, a modified design approach for estimating flexural capacities of the partially bonded beams is proposed. The experimental flexural capacities are in close agreement with the values predicted using the modified design approach. Keywords: carbon fiber-reinforced polymer (CFRP); cyclic behavior; ductility; partially bonded; prestressed concrete beam.
Increasing the utilization efficiency of sulfur electrodes and suppressing the “shuttle effect” of intermediate polysulfides are the key challenge for high‐performance lithium–sulfur batteries ...(LSBs). Herein a facile combined strategy is reported to fabricate novel porous carbon fibers/vanadium nitride arrays (PCF/VN) composite scaffold for the storage of sulfur via a facile chemical etching united solvothermal–supercritical fluid method. More active sulfur can be stored in the PCF/VN backbone and dual blocking effects associated with “physical block and chemical absorption” for polysulfides are achieved in the PCF/VN/S integrated electrode. The PCF with highly porous structure provides large space to accommodate active sulfur and possesses cross‐linked maze channels to physically immobilize the polysulfide species. The VN nanobelt arrays demonstrate strong ability for chemically anchoring the polysulfides, thus retarding the shuttle effect. Due to the unique structure and dual confining effect, the designed PCF/VN/S electrode shows a high reversible capacity of 1310.8 mA h g−1 at 0.1 C, an extended cycle life (1052.5 mA h g−1 after 250 cycles) as well as enhanced rate capability, much better than other counterparts (CF/VN/S, PCF/S, and CF/S). This work opens a new door for fabricating high‐performance integrated electrodes for LSBs.
A novel porous carbon fibers/vanadium nitride arrays (PCF/VN) composite scaffold is demonstrated as the promising sulfur host for high‐performance Li‐S batteries. A dual polysulfides blocking strategy associated with “physical block and chemical absorption” is successfully verified in the designed PCF/VN/S electrode, which shows more effective sulfur utilization, prolonged cycling life, and enhanced high‐rate performance.
The shape memory polymers (SMPs) have an interesting capability of keeping a temporary shape and then recovering the original shape when subject to a particular external stimulus. However, due to ...SMP's relatively low mechanical properties, the use of SMP in a wider range of engineering applications is limited. As such SMPs need to be reinforced before use in engineering applications. This paper presents the mechanical properties, thermomechanical characteristics, photothermal behaviour and light activation of 0/90 woven carbon fibre reinforced shape memory epoxy composite (SMPC) made out of prepreg material. Prepreg is a widely used manufacturing technique for large-scale engineering applications. The experimental results have demonstrated that the structural performance of the SMPC has increased significantly due to carbon fibre reinforcement as anticipated. According to ASTM standard D 3039/D 3039M-00, the mode of tensile failure was identified as “XMV”, where the failure is an explosive type. The dynamic mechanical analysis has revealed that the shape fixity and recovery ratios of the SMPC are 100% and 86% respectively. Under the constrained condition, the stress has been recovered up to 5.24 MPa. The SMPC was exposed to five different power densities of 808 nm and the resultant activation has been systematically investigated. Interestingly, the SMPC has been heated over its glass transition temperature, once it is exposed to a power density of 1.0 W/cm2. Furthermore, the applicability of carbon fibre reinforced SMPC for a deployable solar panel array, intended for remote and localized activation is demonstrated. The SMPC will be a potential candidate for space engineering applications, because of its enhanced mechanical properties and ability of photothermal activation.
Lithium (Li) metal‐based battery is among the most promising candidates for next‐generation rechargeable high‐energy‐density batteries. Carbon materials are strongly considered as the host of Li ...metal to relieve the powdery/dendritic Li formation and large volume change during repeated cycles. Herein, we describe the formation of a thin lithiophilic LiC6 layer between carbon fibers (CFs) and metallic Li in Li/CF composite anode obtained through a one‐step rolling method. An electron deviation from Li to carbon elevates the negativity of carbon atoms after Li intercalation as LiC6, which renders stronger binding between carbon framework and Li ions. The Li/CF | Li/CF batteries can operate for more than 90 h with a small polarization voltage of 120 mV at 50% discharge depth. The Li/CF | sulfur pouch cell exhibits a high discharge capacity of 3.25 mAh cm−2 and a large capacity retention rate of 98% after 100 cycles at 0.1 C. It is demonstrated that the as‐obtained Li/CF composite anode with lithiophilic LiC6 layers can effectively alleviate volume expansion and hinder dendritic and powdery morphology of Li deposits. This work sheds fresh light on the role of interfacial layers between host structure and Li metal in composite anode for long‐lifespan working batteries.
Lithiophilic LiC6 layers are in situ formed on the surface of a carbon fiber (CF) host due to the spontaneous reactions of carbon and lithium, which benefit the uniform deposition of Li ions. A Li/CF composite anode with lithiophilic LiC6 layers can effectively alleviate volume expansion and hinder dendritic/powdery morphology of Li deposits, exhibiting ultrahigh cycle stability in working lithium metal pouch batteries.
