Polyester polyols for waterborne polyurethanes and hybrid dispersions

In this study, environmentally friendly polyester based polyurethane dispersions (PUDs) were synthesized using various combinations of isophthalic acid, adipid acid and maleic anhydride (IPA-AA-MA). A triangular empirical model was employed to optimize total number of experiments for optimal performance of polyurethane dispersions. In addition to PUDs, polyurethane/acrylate hybrid dispersions (PU/AC) were synthesized using graft copolymerization method to enhance the performance/properties of PUDs and for potential cost benefit.The influence of molar ratio and diacid type on the thermo-mechanical and physico-chemical properties of PUDs and PU/AC hybrids was studied. Results revealed that hybrid sample based on IPA:MA exhibited superior performance properties in terms of thermal stability, Tg, hardness, chemical resistance and colloidal stability, though their solvent resistance was relatively poor. Interestingly, PUD based on equimolar mixture of IPA:AA also exhibited better thermal and colloidal stability with intermediate hardness and chemical resistance properties between PUDs based on aliphatic and aromatic diacids.Scanning electron microscopy (SEM) results indicated better polyurethane/acrylate compatibility in hybrid dispersion based on IPA:MA, resulting in homogeneous phase morphology.