Abstract
Density of rigid polyurethane foam (RPF) has a major effect on its mechanical properties
which, in turn, determine the performance level in different applications. Several RPF
samples were prepared through free and non-free rise foaming with different densities by
changing the weight percent of its major chemical constituents. Moreover, some additives
were used to change the density in the range of 40-900 kg/m3. Stress-strain curves of selected
samples showed clearly the effect of density on the mechanical properties (such as elastic
modulus and plateau stress values), effect of load direction on resistance of samples to the
applied load, and effect of preparation method (in high density samples) on the mechanical
properties. Finally, Stress-strain curves were used to assess the rigidity level change due to
chemical formulation nature change.