A point of major concern in carbon fiber reinforced polymer (CFRP) composites is the interface between the carbon fibers (CFs) and the polymer matrix, which acts as the weakest link. Researchers have tried to work around this drawback by modifying the fiber or the matrix via the addition of nanofillers or using chemical treatment methods. In this review, the progress made in the last decade for enhancing the mechanical performance of CFRP composites by applying the aforementioned methods has been covered. Another aspect of CFRP composites that has limited their adaptability is their susceptibility both at sub-zero and at elevated temperatures. In the later part of this review, the co-relation between different service temperatures and the various mechanical properties of CFRP composites and has been elaborated upon. A better understanding of temperature dependent mechanical response would empower us to tailor the properties of CFRP composites depending on the in-service temperature conditions.

Two methods of enhancing the mechanical performance of glass fiber reinforced polymer (GFRP) composites, namely the formation of an interpenetrating polymer network (IPN) of two thermoset polymers (epoxy and vinyl ester) and the addition of nanofillers (nano Al2O3) have been implemented simultaneously. The content of nano Al2O3 (0.1, 0.4, and 0.7 wt% of the polymer matrix) in the glass fiber reinforced epoxy‐vinyl ester IPN (GEVIPN) composite significantly affected its mechanical performance. Incorporation of 0.1 wt% nano Al2O3 in GEVIPN composite exhibited 17.69% and 27.64% improvement in flexural strength and toughness, respectively. Additionally, when the composites were subjected to elevated temperature testing, their mechanical performance was drastically affected. However, the test results revealed that nano Al2O3/GEVIPN composites possessed significantly improved mechanical degradation resistance at elevated temperatures. This new composite material could be utilized as structural materials in the civil, automotive, and marine industries. Dynamic mechanical thermal analysis was performed to assess the composites' thermomechanical behavior. Fractography analysis of tested samples revealed the underlying phenomena, which dictate the mechanical performance at each testing temperature. A constitutive deformation model assessed the reliability of this new material at ambient and elevated test temperatures.

Herein, a solution-based route is presented to fabricate Cu­(OH)2/Co­(OH)2 heterostructures directly on copper foil (CF) as a potential electrode material for supercapacitor application. First a CF is etched to form uniform Cu­(OH)2 nanobelt-like structures on its surface. Using the same CF as the substrate, Co­(OH)2 nanosheets are electrochemically grown on Cu­(OH)2 nanobelts to form a Cu­(OH)2/Co­(OH)2 heterostructure at room temperature. The electrodeposition duration determines the density of Co­(OH)2 nanosheets on the substrate. With an electrodeposition duration of 900 s, a maximum areal capacitance is achieved and thus the same duration is used for forming the heterostructure for device fabrication. An areal capacitance of 413 mF cm–2 is obtained for CF/Cu­(OH)2/Co­(OH)2, which is higher than those for CF/Co­(OH)2 (344 mF cm–2) and CF/Cu­(OH)2 (44 mF cm–2) at 5 mA cm–2. This demonstrates the direct use of a surface-modified binder-free electrode in supercapacitor applications. A more detailed analysis following Trasatti and Dunn’s method reveals the primary charge storage through the diffusion-controlled process. Additionally, the performance of an asymmetric supercapacitor device is demonstrated with CF/Cu­(OH)2/Co­(OH)2 as a positive electrode, activated carbon on CF as a negative electrode, and polyvinyl alcohol–KOH gel as the solid-state electrolyte. An areal capacitance of 113 mF cm–2 at 2.5 mA cm–2 is achieved with an energy density of 3.5 × 10–2 mW h cm–2 at a power density of 1.87 mW cm–2 with a 1.5 V voltage window. A capacitance retention of 81% is measured after 12,000 galvanostatic charge–discharge cycles.

The study aims at investigating the mechanical behavior of carbon fiber reinforced polymer (CFRP) composites modified with graphene carboxyl at elevated temperature (ET-110 C) and understanding the effect of electrophoretic deposition bath concentration (0.5 g/L, 1.0 g/L, and 1.5 g/L) on their mechanical behavior at ET. The 1.5 g/L composite has revealed a maximum improvement in energy absorbed before failure of 33.25% at RT and 22.54% at ET for flexural testing and $35% at RT for short beam shear testing, over neat CFRP composite. The modified composites have shown an improved flexural strain to failure at both RT and ET, with 1.5 g/L composite exhibiting maximum enhancement of 12.41% at RT and 26.52% at ET over neat composite. However, at ET, modified composites exhibited lower flexural strength and interlaminar shear strength values in comparison to that of neat. Viscoelastic behavior of all composites was studied to understand bath concentration's effect on thermal behavior via dynamic mechanical thermal analysis. Differential scanning calorimetry was employed for governing the glass transition temperature of composites.Fractography of tested samples (both ET and RT) was performed utilizing a scanning electron microscope to determine the prominent failure mode.

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