In this research, the usage of single wall carbon nanotubes (SWNTs) and nanoclays in the resin transfer molding (RTM) of biaxially stitched micro-fiber reinforced epoxy matrix composites was investigated to evaluate the role of nanoscale reinforcements on the wetting, flow and end-properties of composites through multi-scale effects. The study primarily focused on characterization of the state of dispersion and curing of nanoscale reinforced epoxy polymers, assessment of the relative importance of viscous forces over interfacial forces and the wettability of glass fabrics by the nanoscale reinforced epoxy polymers, analysis of complex flow of nanoreinforced epoxy systems through glass fiber porous media by several flow properties and evaluation of the properties of hybrid epoxyglassfiber composites enriched with nanoscale particles.
The presence of nanoreinforcements retarded the cure kinetics to some degree such that the activation energies increased with the nanoreinforcement content. Both the
unsteady-state and steady-state relative tow permeabilities were observed to decrease as the nanoclay amount was increased. The presence of nanoclay was observed to reduce the "tow wet-out" with almost 50 % reduction in the steady-state tow permeability with the addition of 4 wt % nanoclay to the reactive epoxy. Contact angle measurements indicated, approximately 21 % increase in the contact angle with the addition of 4 wt % nanoclay to epoxy.
It was found that beyond 0.3 wt % SWNT, RTM of epoxy-60 % biaxially stitched glass fiber systems was not feasible. It was also observed that an addition of SWNT at only 10 % the level of nanoclay caused almost a 25 % increase in steady-state pressure level along with almost an 18 % decrease in permeability. It is believed that nanoreinforcements affected flow rate somewhat differently along the various fabric capillary paths and thereby leading to preferential flow paths in the mold cavity. It is proposed that nanoparticles, particularly at high weight percentages, agglomerate during flow inside the mold cavity and block some intra-tow regions and lead to instabilities in the flow resulting in anomalous pressure differentials at different regions of the flow and unusual permeability results.
While the use of nanoreinforcements reduced oxygen and moisture transport along with thermal expansion coefficient, the mechanical properties were found to decrease due
to the several defects, such as voids and agglomerates introduced during RTM as a result of the differential micro- and macro-flows.