Microstructure and Tensile Mechanical Properties of Anisotropic Rigid Polyurethane Foam

An understanding of the mechanical properties of solid foams facilitates effective use of such materials, which are often deployed in load-bearing applications such as impact absorbers, cushioning and sandwich structures. This study is an experimental investigation that focuses on the deformation response of rigid polyurethane foam to tension. Microstructural features such as the size and geometry of constituent cells and the struts that define the cell edges, as well as their stiffness and tensile strength, are examined. The nature of cell deformation and fracture are identified through microscopy and the associated micromechanics analyzed. Results show that the cells are elongated and thus the foam exhibits anisotropic properties. Flexure of the struts that define the cell edges is the primary mechanism governing deformation and failure. Information on the mechanical, microstructural and deformation characteristics elicited through this investigation will facilitate formulation of idealized cell-based models to account for the mechanical response of rigid polymeric foams.