Synthesis and characterization of waterborne polyurethane based on aliphatic diamine sulphonate and liquefiable dimethylol propionic acid

In this paper, aliphatic diamine sulphonate (AAS-Na) and liquefiable dimethylol propionic acid (LDMPA) were used together to synthesize waterborne polyurethane (WPU) with excellent property. The influence of -COOH/SO3Na molar ratio on the structure and properties of the waterborne polyurethanes were characterized by IR, particle size analysis, DSC, DMA, apparent viscosity, water absorption, contact angle, tensile and peel strength tests. It was found that with decreasing -COOH/-SO3Na molar ratio from 10:0 to 3:7, (1) the particle size of the waterborne polyurethane emulsion decreased, while the apparent viscosity of the samples increased. (2) the water absorption of the WPU films decreased, while the contact angle of the films increased. (3) The tensile strength, elongation at break and peel strength of the samples increased. Furthermore, the results of DMA showed that incorporation of AAS-Na increased the storage modulus of the sample. And the results of DSC showed that with decreasing -COOH/-SO3Na molar ratio from 10:0 to 3:7, T-g of soft segment shifted to lower temperature, which indicated that the micro-phase separation degree of the samples increased.