Carbon fiber reinforced epoxy (CFRE) laminate structures have emerged as futuristic materials having surpassed metals in strength and durability. The interfacial chemistry determines the mechanical ...performance of such laminates. In this study, a unique approach was adopted wherein the alternate layers of the carbon fiber (CF) mat were grown
with ZnO nano-rods and modified with bis-maleimide (BMI), and epoxy resin containing 0.2 or 0.5 wt% graphene oxide (GO) was infused using conventional VARTM technology to enhance the mechanical interlocking of epoxy with the fiber as well as to impart self-healing properties to the laminate. While ZnO rods offer surface roughness thereby facilitating better wetting of epoxy, the Diels-Alder thermo-reversible bonds between BMI and GO facilitate self-healing properties besides improving the interfacial adhesion between epoxy and CF. The rationale behind this work is to synergistically improve the interface-dominated mechanical properties like interlaminar shear strength (ILSS) while maintaining or even improving fiber-dominated properties like flexural strength (FS) as well as imparting considerable recovery in strength post the self-healing cycle. The laminates after this treatment (having 0.5 wt% GO) indeed exhibited 46% improvement in FS and 33% improvement in ILSS properties as well as an ILSS recovery of 70%. The surface analysis suggests that ZnO nano-rods offer surface roughness that helps in the wettability of the matrix on the fibers. In addition, the 2D and 3D representative volume analysis (RVE) model was established to identify the load transfer behaviour in the ZnO-CF-epoxy interface in the microscale reference region. The fractographic analysis confirmed that rigid ZnO nano-rods allowed better matrix adhesion resulting in improved mechanical performance.
Herein, inspired by
Acacia auriculiformis
fruit, the shish-kebab-like growth of ZnO on carbon urchin (ZnO@CU) was designed using microwave radiation, thus leading to a hierarchal 3D structure that ...can promote multiple internal reflections through polarization centers. This hierarchal structure was then dispersed in a designer polyetherimide (PEI) matrix containing dynamic covalent bonds that can undergo metathesis, triggered by temperature, to harness self-healing properties in the composite. Such key attributes are required for their potential use in EMI shielding applications where frequent repairs are indispensable. Morphological investigation revealed that the ZnO flower was periodically nucleated like shish-kebab structures on CU surfaces. CU was designed from short carbon fibers using a facile modified method. The EMI shielding performance of the resulting composites was investigated in the X-band, illustrating a shielding effectiveness of 40.6 dB for 2 wt% of ZnO@CU loading, and the composite can be preserved after the self-healing procedure. The ZnO 'kebabs' on CU shish' facilitated multiple scattering and numerous polarization centers to improve the EMI shielding performances at extremely low filler contents. In addition, the mechanical and thermal properties of the composite showed improved structural integrity and superior resistance to extreme temperatures, respectively. Overall, the proposed ZnO@CU/PEI composite has great potential to fulfill the increasing demands for lightweight EMI shielding materials in many fields.
Herein, inspired by
Acacia auriculiformis
fruit, the shish-kebab-like growth of ZnO on carbon urchin (ZnO@CU) was designed using microwave radiation, thus leading to a hierarchal 3D structure that can promote multiple internal reflections through polarization centers.
Advanced hierarchical carbon fiber epoxy laminates with an engineered interface using in situ-grown ZnO nanorods on carbon fiber resulted in strong mechanical interlocking with the matrix. To further ...strengthen the interface, “site-specific” modification was realized by modifying the ZnO nanorods with bismaleimide (BMI), which facilitates “thermo-reversible” bonds with graphene oxide (GO) present in the matrix. The resulting laminates exhibited an improvement in flexural strength by 20% and in interlaminar shear strength (ILSS) by 28%. In order to gain a mechanistic insight, few laminates were prepared by “nonselectively” modifying the ZnO-grown carbon fiber (CF) with BMI. The “nonselectively” modified laminates showed flexural strength and ILSS improvement by 43 and 39%, respectively. The “nonselective” modification resulted in a strong improvement in mechanical properties; however, the “site-specific” modification yielded a higher self-healing efficiency (81%). Raman spectroscopy, scanning electron microscopy (SEM) micrographs, atomic force microscope (AFM) analysis, and contact angle analysis indicated a strong interaction of the modified CFs with the resin. Enhanced surface area and energy, along with a decrease in segmental molecular mobility observed from dynamic mechanical analysis, confirmed the mechanism for a better performance. Microscopic images revealed an improved interfacial behavior of the fractured samples, indicating a higher interfacial adhesion in the modified laminates. Besides mechanical properties, these laminates also showed excellent electromagnetic interference (EMI) shielding performance. The laminates with only ZnO-modified CF showed a high shielding effectiveness of −47 dB.
Polymer nanocomposites with exceptionally high mechanical properties owing to strong interfacial attraction have garnered tremendous interest in the research community. In general, tough and robust ...polymer nanocomposites are usually obtained via dispersing a nano‐flaky filler in the polymer matrix, although the strategy is only sometimes practically viable. To this end, in this work, a facile strategy has been adopted to achieve a strong and tough polymer nanocomposite. A novel mussel‐inspired full interpenetrating polymeric network (IPN) consisting of polyvinylalcohol and polydopamine was prepared. This technique helped integrate the advantages of dopamine chemistry with forming a full IPN using Borax as a common crosslinker. The infusion of 1 wt% acid‐modified carbon nanotubes (ACNT) in the IPN matrix helped greatly improve the current state‐of‐the‐art. The synergistic effect of nano‐reinforcement and formation of ester linkage through a substantial amount of di‐diol complexation dominated and accounted for the significant enhancement of mechanical properties. This is further supported by decreased intensity of free OH groups in the FTIR investigations, viscosity enhancement from rheological behavior, and temperature‐dependent dynamic mechanical property analysis. Such an IPN structure is a promising way to enhance mechanical properties.
In this article, Mode I interlaminar fracture toughness, flexural and interlaminar shear strength (ILSS) properties of graphene oxides (GOs) coated carbon fibre reinforced epoxy composites have been ...studied. Here, a simple electrophoretic deposition technique was employed to coat the GO and reduced graphene oxide (rEGO) fillers onto the carbon fibre (CF) surfaces. To partially reduce the coated GOs, the GOs coated CFs were thermally annealed at 200 °C for 2 h. Vacuum assisted resin transfer moulding (VARTM) technique was employed to fabricate hybrid epoxy composites with three variants of GOs (namely, GO, rEGO, TrGO) coated CFs. The modified composite laminates have demonstrated substantial improvement in ILSS properties, where composites based on GOs coated CFs exhibited the highest enhancement of 47%. Similarly, flexural and Mode I fracture properties of composites also delivered significant improvements in their values, gaining at 25% and 14% respectively. Interesting observations were made from the fracture surface images of double cantilever beam (DCB) test specimens of composites. Through-thickness electrical conductivity of thermally reduced GOs coated and rEGOs coated CF composites have shown a substantial increment of 127% and 90% compared to uncoated composites.
Fiber-reinforced polymer composites as a structural material have garnered tremendous interest over the past few decades. In particular, carbon fiber-reinforced epoxy (CFRE) laminates have seen ...extensive use in the aircraft and aerospace industry. The role of the interface between the matrix and fiber is critical and dictates the overall structural properties of the CFRE laminate. Herein, we attempt to use a commercially viable, green, and facile approach, electrophoretic deposition (EPD), to deposit covalently coupled multiscale graphene oxide (GO)/carbon nanotube (CNT) nanoconstructs onto carbon fiber (CF) fabric. The rationale behind using these hybrid conjugates is to exploit the positive synergistic effect of combining two-dimensional (2D) GO and one-dimensional (1D) CNT nanoparticles, which provide strengthening through different mechanisms resulting in a stronger matrix/fiber interface. The modified laminate with just 0.1 wt % GO/CNT content exhibited an improvement in flexural strength (FS) by 24% and interlaminar shear strength (ILSS) by 30% compared to the neat CFRE. Scanning electron microscope (SEM) micrographs confirmed uniform and homogeneous GO and GO/CNT deposition on CF. Raman, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses validate the successful functionalization of CNT and covalent coupling of GO and CNT. Atomic force microscope (AFM) and contact angle analyses indicate improved interaction between the CF and matrix. The deposition of the GO/CNT nanoconstruct on the CF improved the performance of CFREs owing to enhanced wettability, surface free energy, and surface roughness, leading to increased mechanical interlocking between the epoxy and CF at the interface. Dynamic mechanical analysis showed decreased segmental motion of epoxy chains due to improved interfacial adhesion following modification. Interesting observations were made in SEM fractography, which showed considerably different failure mechanisms in the modified CFREs. Electromagnetic interference (EMI) shielding effectiveness of −45 dB was achieved in the case of the GO/CNT-CFRE system. Electrothermal heating and de-icing performance of the modified system were also explored in this study. This versatile approach can open up new avenues for CFRE modification leading to considerably improved performance.
Carbon fiber reinforced epoxy (CFRE) laminate structures have emerged as futuristic materials having surpassed metals in strength and durability. The interfacial chemistry determines the mechanical ...performance of such laminates. In this study, a unique approach was adopted wherein the alternate layers of the carbon fiber (CF) mat were grown
in situ
with ZnO nano-rods and modified with bis-maleimide (BMI), and epoxy resin containing 0.2 or 0.5 wt% graphene oxide (GO) was infused using conventional VARTM technology to enhance the mechanical interlocking of epoxy with the fiber as well as to impart self-healing properties to the laminate. While ZnO rods offer surface roughness thereby facilitating better wetting of epoxy, the Diels-Alder thermo-reversible bonds between BMI and GO facilitate self-healing properties besides improving the interfacial adhesion between epoxy and CF. The rationale behind this work is to synergistically improve the interface-dominated mechanical properties like interlaminar shear strength (ILSS) while maintaining or even improving fiber-dominated properties like flexural strength (FS) as well as imparting considerable recovery in strength post the self-healing cycle. The laminates after this treatment (having 0.5 wt% GO) indeed exhibited 46% improvement in FS and 33% improvement in ILSS properties as well as an ILSS recovery of 70%. The surface analysis suggests that ZnO nano-rods offer surface roughness that helps in the wettability of the matrix on the fibers. In addition, the 2D and 3D representative volume analysis (RVE) model was established to identify the load transfer behaviour in the ZnO-CF-epoxy interface in the microscale reference region. The fractographic analysis confirmed that rigid ZnO nano-rods allowed better matrix adhesion resulting in improved mechanical performance.
ZnO nano-rods modified hybrid CFRE laminates for superior mechanical strength.
Smart and Functional Textiles is an application-oriented book covering a wide range of areas from multifunctional nanofinished textiles, coated and laminated textiles, wearable e-textiles, ...textile-based sensors and actuators, thermoregulating textiles, to smart medical textiles and stimuli-responsive textiles. It also includes chapters on 3D printed smart textiles, automotive smart textiles, smart textiles in military and defense, as well as functional textiles used in care and diagnosis of Covid-19.
