Investigation of the Prepolymer Mixing Process to Prepare Water-based Polyurethanes

A series of the water-based polyurethanes with different ratios of sulfonated ionic center were synthesized. The prepolymer mixing method was applied for preparing of the samples. Poly(є- caprolactone), H12MDI, 1,4-butaindiol, N,N-bis(2-hydroxyethyl)-2-amino ethane sulfonic acid sodium salt (BES sodium salt) were used. At first, the proper amount of polyol and excess diisocyanate were reacted to form the prepolymer. Then, ionic center was incorporated into the polyurethane backbone. Afterward, chain extension step was performed. For preparation of the water-based polyurethane, water was added to the mixture with a rate of 750 rpm. Control of the water addition rate was very important to obtain the homogeneous emulsion. Here, the synthesis route, IR spectroscopy and dynamic mechanical thermal analysis (DMTA) of the obtained samplesare reported. The results showed that the strong H-bonded carbonyl groups were formed in the samples and intermolecular interaction of the hard segments with the soft segments occurred. Also, the glass transition temperature (Tg) of the samples moved toward higher temperature as BES values were increased. Storage modulus increased with increasing BES quantities.