Investigation of particulate filtration of alumina nano-particles in VARTM processing of hybrid composites

Hybrid composites composed of particulate inclusion in the resin for fiber reinforced plastics are manufactured using the low-cost vacuum assisted resin transfer molding (VARTM) composite technology. Particulate inclusions are known to influence to some degree, the thermo-mechanical properties of resin systems and are dispersed in the resin before fabrication by this low cost processing technique. Particulates are dispersed in resin systems via ultrasonic agitation to obtain exfoliated/ intercalated particle dispersion morphology. Highly dispersible grade particulate boehmite nano-alumina with 110nm mean particle size was predispersed in a low viscosity epoxy resin prior to VARTM processing. Fiber lay-up with high tow density (10K) S-glass fabric was impregnated. The flow regime of the infused modified resin and the mold setup configuration influence the percolation and filtration of the particulates in the mold lay-up. The occurrence of filtration depends on the mold layup configuration and flow regime. The flow pattern is varied to induce filtration by transverse percolation through the distribution media and through-fabric longitudinal flow schemes (without distribution media). Resin samples from the flow front were collected and are studied via thermogravimetric analysis (TGA). The dynamics of particulate flow and the potential filtration effects due to the fiber lay-up during the infusion of low viscosity resin are studied. These are based on analyzing the residual mass of the 110nm alumina particles in epoxy resin that is collected after infusion through the fiber lay-up during the manufacture of advanced hybrid composite.