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Hybrid graphene filled glass/sisal fiber-reinforced epoxy nanocomposites were successfully synthesized with different weight percentages (0%, 0.25%, 0.5%, 0.75% and 1%) of graphene nanoplatelets. The objective of this study was to investigate the effect of weight fraction of graphene on the mechanical and physical properties of the hybrid glass/sisal fiber-reinforced epoxy nanocomposites such as tensile, flexural, hardness, density, void content, flammability, water absorption and thickness swelling. The hybrid nanocomposites were fabricated using the vacuum bag-assisted hand lay-up technique. Different layup sequences were achieved by changing the position of the glass/sisal fiber layers, maintaining a total of five layers in each composite. The obtained results suggested that the addition of 1% graphene nano filler into the sisal/glass hybrid composite enhanced the tensile strength by 49.7% and Young's modulus by 60%. Among GNP reinforced hybrid composites, highest value of toughness (16 J) was found in case of the composite containing 1 wt.% GNP. However, when 0.5% of GNPs were added in the composite, the flexural strength and modulus reached a maximum of 306 MPa and 25 GPa, respectively, which are 228% and 362% greater than sisal/glass hybrid composites. The water absorption of the composite sample containing 0.5% GNPs was 4.62% lower than those of other hybrid glass/sisal fiber reinforced epoxy composite. Furthermore, addition of 0.5 wt% GNP resulted in a decrease in the burning rate of the hybrid composite from 11.22 mm/min to 7.6 mm/min and from 23.13 mm/min to 20.18 mm/min, respectively. [ABSTRACT FROM AUTHOR]

In the present study, the bending analysis of multi walled carbon nanotubes (MWCNTs) reinforced laminated tapered spherical composite panels subjected to transverse loading conditions is carried out using the finite element method (FEM) with displacement fields derived from high order shear deformation theory. In this regard, the elastic properties of the polymeric nanocomposite, considering the MWCNTs agglomeration, waviness and interphase thickness between the MWCNTs and polymer matrix were computed by employing various micromechanical approaches. Subsequently, glass-fiber were introduced as a reinforcement phase, and the overall elastic properties of a three-phase MWCNT/fiber/polymer hybrid nanocomposite material were obtained using Chamis model. The accuracy of the developed FE formulation were verified using the experimental and numerical data available in the open literature. After verification, the deflection and stresses of the panel are numerically determined for various taper configurations. Further, detailed parametric analysis is carried out to explore the influence of various parameters such as CNT content, agglomeration, waviness, interphase area, thickness ratio, curvature ratio and taper configurations on the bending results of laminated tapered spherical panels. It was observed that an increase in the weight fraction of CNTs, an equal number of agglomeration parameter and the thickness of the interphase have a positive effect in minimizing the deflection and stresses. It was also observed that the TC-2 and TC-3 taper configurations results the highest and lowest deflection. Finally, it can be concluded the current work can serve as a guide for the effective design and development of CNT reinforced composite structures. [ABSTRACT FROM AUTHOR]

The current study focuses on the investigation of the synergetic effect of graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) on the flexural properties, hardness and water absorption characteristics of glass fiber reinforced polymer (GFRP) laminated composite materials. The laminated composite materials were fabricated with various configuration of filler reinforcements using vacuum assisted hand lay-up technique. Further, micromechanical analysis was performed using Halpin-Tsai model to investigate the synergistic effect of CNT/GNP hybrid glass fiber reinforced epoxy nanocomposites. It was observed that the CNT and GNP reinforced hybrid composite exhibited highest value of flexural strength and hardness; the respective values being 38% and 29% higher in comparison to the neat epoxy composite. Furthermore, among GNP and CNT, the composite containing former reinforcement exhibited better mechanical properties. The composites containing nanoparticles also exhibited better water uptake characteristic, where the weight gain for hybrid composite was 1.004%, whereas, for neat epoxy composite, the weight gain was 1.210%. This was attributed to the ability of nanofillers to restrict the intermolecular movement of the surrounding GFRP composites, which delays the relaxation of polymer chains, thereby reducing the diffusion of tiny molecules through the composites. It was also observed that the addition of GNPs has a strong effect on the elastic properties of the hybrid glass fiber reinforced epoxy nanocomposite than the addition of CNTs. [ABSTRACT FROM AUTHOR]