Effect of Hydrophilic Chain Extenders on Properties of Hyperbranched Waterborne Polyurethane

Using hydroxyl terminated hyperbranched polymer as the core, dimethylol propionic acid (DMPA), dimethylolbutanoic acid (DMBA), carboxylic acid type monomer (DMCA) as the hydrophilic chain extenders respectively, three different types of hyperbranched waterborne polyurethane leather finishing agents were synthesized. The structures and properties of the products were characterized by FT-IR, SEM, AFM and TG. Simultaneously, the mechanical properties, surface wettability and water and solvent resistance of three films were studied. The results found the order of crystallinity to be: DMBA-HWPU <DMPA-HWPU <DMCA-HWPU, concerning the particle size, that of DMPA-HWPU emulsion was minimal; the elongation at break of DMCA-HWPU was the highest at 276.55%; the heat resistance of three types of urethane was nearly the same.