Fabrication of Laminated Nanocomposites by Vacuum-Assisted Deposition of Clay Onto Glass/Epoxy Prepregs

In this study we are presenting a novel method for introducing nanoclay in epoxy matrix composites. The method involves vacuum-assisted deposition of fine clay particles directly onto the surface of commercially available prepregs. A deposition chamber is developed that is capable of breaking down nanoclay particles by subjecting them to shear and depositing them uniformly onto prepregs at room temperature. By using the deposition chamber, a thin layer of nanoclay is deposited on 101.6mm×101.6mm woven glass/epoxy prepregs. Twelve of these prepregs are stacked and cured by an autoclave at a temperature of 121°C under a constant pressure of 0.2MPa (30psi) for 1 hour. After the curing is complete, the laminates are cut into 10.8mm×31.7mm samples for three-point bending tests, glass transition temperature measurements and microstructural characterization. The improvements in mechanical properties such as flexural strength, flexural stiffness, and glass transition temperature by the addition of nanoclay are presented. Nanocomposite morphology is studied by light microscopy and scanning electron microscopy. Marginal improvements in mechanical properties are observed with only 0.6% nanoclay content. The flexural stiffness improved by 4% while maintaining the flexural strength constant at around 400Wa. Glass transition temperature is measured as 128°C for samples with and without nanoclay. However, significant differences in microstructure are observed. Although both samples contain micro-voids, these voids are observed to be more extensive in samples involving nanoclay.