Compression properties and cellular structure of polyurethane composite foams combining nanoclay and different reinforcements

Abstract

In the present work we prepared and characterized several polyurethane (PU) composite foams by combining variable concentrations of nanoclay (montmorillonite, MMT) with metal wires or low cost cellulosic-based reinforcements, with the objective of developing multi-scalar rigid foams for structural applications. The addition of MMT 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 PU 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 MMT and the macroscopic metal wires or cellulosic-based reinforcements further reduced the cell size of foams and resulted in foams with similar compressive collapse strengths as the unfilled ones for considerably lower relative densities, hence demonstrating their effectiveness as mechanical reinforcements of rigid PU foams and opening up new possibilities in terms of developing low cost lightweight materials.