LAUSR

In the present study, response surface methodology is used to synthesize hyperbranched polyesters based on variables reaction time, ratio of monomer to core, and type of catalyst. Then, the synthesized polyesters were used for preparing hyperbranched urethane acrylates in two steps. In order to characterize these polymers, infrared spectroscopy and proton nuclear magnetic resonance is used. Hyperbranched urethane acrylates were formulated and cured by ultraviolet irradiation. Finally, dynamic mechanical thermal analysis (DMTA) test is used to investigate the viscoelastic properties of the coatings. The results of DMTA test were shown that the higher molar mass distribution of hyperbranched polyester is associated with less uniformity of cross-link network of cured samples. Also by increasing the molar mass of hyperbranched polyester, glass transition temperature of cured urethane acrylate resins was increased. The samples produced by using methane sulfonic acid catalyst show higher strength and more uniform cross-link network than the those made by sulfuric acid catalyst.