Analysis and Characterization of Quasi-Prepolymers Obtained from Polyethylene Glycol 1500 and 4, 4´-Diphenylmethane-DiIsocyanate

The quasi-prepolymers were synthesized by using the prepolymerization method with polyethylene glycol (PEG) 1500 and polymeric 4,4´-diphenylmethano diisocyanate (pMDI) in different molar ratios.The monomers and prepolymers were characterized by means of FTIR, 1 H-NMR and 13 C-NMR.It was possible to demonstrate that by decreasing the n(NCO)/n(OH) ratio, the average molecular weight of the prepolymers increased.It was also possible to show that by decreasing the prepolymer NCO content, the viscosity of the prepolymers increased.These properties have to be considered when a formulation of final polyurethane (PU) employing the isocyanate prepolymers and other diols is made.