Investigation of the Polyol Types and Isocyanate Concentrations on the Rheological, Morphological and Mechanical Properties of Polyurethane Foams

Abstract 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.