Effect of nanofillers on low energy impact performance of sandwich structures with nanoreinforced polyurethane foam cores.

Sandwich panels were fabricated with nanoclay-filled polyurethane foams and glass fiber-reinforced polyamide and polypropylenes face sheets. Nanoclay-filled foam cores, with organophilic montmorillonite loadings of 0-10 wt%, were synthesized through polyaddition of the polyol premix with 4,4'-diphenylmethane diisocyanate, and bound to the injected molded face sheets. Produced sandwich structures were then subjected to low energy impact (15 J) tests under localized point and surface loads, in an instrumented impact test setup. Additionally, quasi-static compressive behavior of the sandwiches panels was studied. The results showed that the addition of nanoclay in the polyurethane foam core improved both energy absorption and maximal deflection during impact. The improvement in energy absorption was between 66% and 92% for polypropylenes face sheet sandwiches and 23% and 34% for the polyamide face sheet sandwiches during point load. Furthermore, an increase in the compression modulus of 20-37% was recorded for the sandwiches with polyamide face sheets