Tensile and compression behavior of woven glass/epoxy nano composites based on spraying methodology

Nano composites have been utilized increasingly because of their high strength, stiffness, toughness, and through-thickness properties. The incorporation of carbon nano fibers with a high aspect ratio and extremely large surface area into glass/epoxy polymer composites improve their tensile and compression properties significantly. Although a number of efforts have been made to improve various properties by mixing nano particles directly into resin, however, it could lead to high viscosities which create problems during processing. In this particular study, an attempt has been made to investigate tensile and compression behavior of nano composites by using, state of the art, a different technique i.e spraying the Carbon Nano Fibers (CNF) on dry woven glass pre-form before infusion. The nano composite samples were prepared using a spraying methodology i.e dispersing the 2.0 weight percent CNF solution on glass fabric, and evaporating the solvent such that only nano fibers remain on perform, followed by Vacuum Assisted Resin Transfer Molding (VARTM). Tensile and compression tests were performed to evaluate the effectiveness and behavior of CNF addition on these mechanical properties. Results indicated simultaneous improvement in tensile and compression properties by incorporating a very small amount of carbon nano fibers into the matrix system. 18-21 percent improvement in tensile strength and 6-9 percent in compressive strength, with respect to the neat composite. The rise in their modulus has also been discussed in detail and part of this study. For in-depth analysis, microscopic approaches were also carried out to investigate the fracture behavior and mechanism of material. Scanning electron microscopy of fractured surfaces revealed improved primary fiber-matrix adhesion and indications of CNF-induced matrix toughening due to the presence of CNFs. SEM evaluation also revealed relatively less damage in the tested fracture surfaces of the nano phased composites in terms of matrix failure, fiber breakage, matrix-fiber de-bonding, and de-lamination, compared to the neat system.