In this article, modification of carbon fiber surface by carbon based nanofillers (multi‐walled carbon nanotubes [CNT], carbon nanofibers, and multi‐layered graphene) has been achieved by electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in‐situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter‐laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in‐situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites.

The exceptional and distinctive properties of the allotropes of carbonaceous nanomaterials like carbon nanotubes and graphene have attracted many researchers and engineers to enhance the performance of fibrous polymeric composites. This article extrapolates the synergetic impact of carbon nanotube (CNT) and multi-layered graphene (MLG) reinforcement onto the mechanical performance of glass fiber/epoxy composites. Magnetic stirring and ultra-sonication process have been carried out under optimized parameters for incorporation of CNT-MLG into the epoxy polymer. Incorporation of 0.1wt% of carbon nanotube to the glass fiber/epoxy composites enhances a flexural strength of 10% and addition of 0.1 wt. % of multi layered graphene to the glass fiber/ epoxy composites enhances a flexural strength of 6% when differentiated with neat GE. Embodiment of 0.1 wt. % CNT and MLG to the glass fiber/epoxy composites in three different ratios like 1:1, 1:2 and 2:1 showcases a 13%, 12.25% and 14.7% enhancement in the flexural strength respectively with respect to the neat glass fiber/epoxy composites when tested at room temperature. Among them, the ratio 2:1(CNT: MLG) contributes higher strength due to the combined action of high aspect ratio of CNT and higher specific surface area of multi-layered graphene thus, facilitating efficient stress transfer from matrix to the reinforcements. Thermal characterizations have been carried out using differential scanning calorimetry (DSC). The fractography of the samples is examined through the scanning electron microscope.

Fiber reinforced polymeric (FRP) composite materials are currently used in numerous structural and materials related applications. But, during their in-service period these composites were exposed to different changing environmental conditions. Present investigation is planned to explore the effect of thermal shock exposure on the mechanical properties of nanoTiO2 enhanced glass fiber reinforced polymeric (GFRP) composites. The samples were conditioned at +70°C temperature for 36 h followed by further conditioning at – 60°C temperature for the similar interval of time. In order to estimate the thermal shock influence on the mechanical properties, tensile tests of the conditioned samples were carried out at 1 mm/min loading rate. The polymer phase i.e. epoxy was modified with different nanoTiO2 content (i.e. 0.1, 0.3 and 0.5 wt. %). The tensile strength of 0.1 wt.% nanoTiO2 GFRP filled composites exhibited higher ultimate tensile strength (UTS) among all other composites. The possible reason may be attributed to the good dispersion of nanoparticles in polymer matrix corresponds to proper stress transfer during thermal shock conditioning. In order to access the variations in the viscoelastic behavior and glass transition temperature due to the addition of nanoTiO2 in GFRP composite and also due to the thermal shock conditioning, dynamic mechanical thermal analysis (DMTA) measurements were carried out. Different modes of failures and strengthening morphology in the composites were analyzed under scanning electron microscope (SEM).

In this article, alteration in the mechanical performance of glass fiber/epoxy (GE) composite due to individual and simultaneous incorporation of multi‐walled carbon nanotubes (CNT) and multi‐layered graphene sheets (MLG) in both their pristine and oxidized forms are discussed. Further, the effect of two different nanofiller concentrations (0.1 and 0.3 wt%) were also studied to optimize the performance. Flexural testing of these composites was performed at room temperature (RT), 70 and 110°C in‐situ temperatures to understand their temperature dependence behavior. From all considered composites, GE composite with 0.1 wt% of oxidized CNT and MLG mixture (O‐(CNT‐MLG)) (1:1) showed best flexural performance at all the in‐situ temperatures. The presence of oxidized CNTs and MLGs in the GE composite provided a synergetic strengthening effect like CNT pull‐outs and crack bridging confirmed through SEM imaging. Besides, oxidation helped in the dispersion of CNT and MLG in the composite. Glass transition temperature (Tg) of all the considered composites was evaluated using Differential Scanning Calorimetry (DSC). Fourier Transformed Infra‐red Spectroscopy (FTIR) was also conducted to confirm the functionalization of CNT and MLG after oxidation. During the fractography study, these composites showed variation in fiber/matrix interfacial bonding, matrix deformation, dispersion of nanofillers and fiber imprints, which helped to understand different failure modes responsible for the gross failure of the composites.