tri-functional bio-friendly cross-linker for uv-curable coatings: synthesis and study of viscoelastic properties

Protection of the environment and keeping it from contaminants are critical issues. polymers and oil-based plastics are unrenewable and entail a wide range of environmental pollution due to the long degradation. this study aims to synthesize biobased coatings using natural substances, and evaluate their viscoelastic properties. accordingly, first, uv-curable trifunctional castor oilbased waterborne urethane acrylate as a biofriendly crosslinker was synthesized. next, different weight percentages of the synthesized crosslinker were added to the uv-curable urethane acrylate resin, followed by uv radiation exposure to prepare, different flexible composite coatings. ft-ir spectroscopy was used to examine the progress of the crosslinker synthesis. the particle size analysis confirmed the stability and homogeneous distribution of the crosslinker particles in the emulsion. by dmta analysis, viscoelastic characteristics of the films were studied. as a result, adding specific weight percentages of crosslinkers to the polymer matrix caused an increase in storage modulus and improvement of tg of the coatings. the crosslink density of the film coatings was estimated from dmta. the more weight percent of the crosslinker, the more is the cross-link density.