This research studies the preparation and characterization of polyurethane foams, which
are produced from the reaction of isocyanate Methylene Diphenyl Diisocyante “MDI” and polyol
with water being used as a chemical blowing agent. The effect of isocyanate concentration on the
cross-linking formation of polyurethane samples and its influence on the final properties of the
foams were investigated. Each type of polyols (Local commercial market polyester, Quickmast120
and Quickmast110 polyether) were mixed with the isocyanate at equivalent ratio of (isocyanate:
polyol) (0.5:1, 1:1, 2:1 and 3:1) to prepare polyurethane foam using one shot method. Rheological
tests were performed for the polyols and isocyanate to find out their effect on the formability
processes. The morphology and structure were performed using FTIR and digital microscopy. The
tensile strength, compression strength and the hardness were conducted to show the effect of
isocyanate concentrations on the mechanical properties of samples. The result display the
Quickmast 120 polyol was unsuitable due to the large cells, unstable rheological properties and
high hardness, which leads to a loss of flexibility of the polyurethane foams. The ratio of (1:1)
(polyol/isocyanate) was the best in terms of the formability of the foam giving the smaller cells size
and the best mechanical characteristics as compared to other concentrations of isocyanate.