The Influence of Chain Extender Type on Physical Properties of Aqueous Polyurethane Dispersions

In this study, an aqueous polyurethane dispersion based on polyester was synthesized. Fourier Transform Infrared Spectroscopy was used to monitor the end point of the polymerization. In addition, the effects of two different chain extenders were studied on the average molecular weight advancement by using gel permeation chromatography. Also, the modification of average particle size, thermal behavior of the basic resin and mechanical properties of the produced paint film were investigated by use of particle size analyzer, differential scanning calorimetry, hardness, flexibility and wet scrub tests, respectively. The results clearly explained that in constant molar ratio of NCO/OH, Using of 1,4 Butanediol as chain extender in comparison to Hexamethylenediamine, followed by decreasing in particle size, increasing in hardness and wet scrub that improved the mechanical properties of the final paint film.