The effects of combining nanoclay and steel wires multi-scalar reinforcements on the structure and properties of polyurethane foams

Abstract

In this paper we prepared and characterized several polyurethane composite foams by combining variable concentrations of organophilic clay (montmorillonite) and metal reinforcement, with the objective of developing novel multi-scalar multifunctional rigid foams. The addition of montmorillonite clay promoted foaming and the formation of finer and more homogeneous cellular structures, resulting in foams with compressive elastic moduli and collapse stresses lower than that of the unfilled polyurethane foams. However, a comparative analysis versus the foams’ relative density demonstrated that both mechanical properties follow one single trend for the two materials. The combination of montmorillonite and metal reinforcement further reduced the cell size of foams, ultimately resulting in foams with similar mechanical properties for considerably lower relative densities. Although no important differences in thermal conductivity were found for the polyurethane foams with adding montmorillonite, the incorporation of the metal reinforcement led to considerably higher thermal conductivities, its value increasing with increasing relative density.