Effect of nanoclay and nanoscale TiO₂ on carbon/glass fibrereinforced polymer composites

Nanofillers dispersion in polymeric matrix has been identified as a novel method to enhance the mechanical properties of Fibre Reinforced Polymer Nanocomposites (FRPNCs). In general, addition of nanofillers in polymeric resin improves the fracture toughness, tensile and other properties of polymer composites. On the other hand, this inclusion significantly reduces the stiffness, strain at rupture and thermal properties. To overcome these limitations, hybrid nanofillers have been introduced in polymer composites. This work aims to investigate the effect of addition of hybrid nanofillers (Nanoclay-TiO₂) on mode I interlaminar fracture toughness (G_IC), tensile as well as flexural characteristics of carbon/glass/epoxy based composites. The pristine epoxy resin was modified with nanoclay and nanoscale TiO₂ nanofillers together with different weight percentages (0.5, 1, 1.5 & 2 wt%) using mechanical stirrer followed by sonication process. The modified epoxy based carbon/glass polymer laminates were fabricated using hand lay-up process. The lay-up sequence considered in this study was (90 °C/90 °G/0 °G)_S, (90 °G/0 °G/90 °C)_S and (90 °G/0 °C/90 °G)_S. The mechanical properties of modified laminates were characterized by DCB test, tensile and three point bending test. The experimental results show that the addition of hybrid nanofillers in epoxy resin increased the mode I interlaminar fracture toughness (G_IC) by 77% at 1.5 wt%, tensile strength by 31% at 1.5 wt%, and flexural strength by 33% at 2 wt%. Further addition of nanofillers (<2 wt%) decrease the mechanical properties of FRPNCs as a result of matrix embrittlement. The toughening mechanisms such as fibre pull-out, fibre breaking, particles debonding, and crack deflection were identified at the fractured surfaces. (paper)