Biodegradability of waterborne polyurethane and polyurethane : polyacrylate coating materials in soil

Despite the continued development of more biodegradable polymers, the existing biodegradation test methods remain unsatisfactory in allowing comparison of test results between different biodegradation tests and correlation with the actual environmental biodegradation of the tested polymers. In an attempt to address these shortcomings and as part of an industrial project to develop biodegradable water-borne polyurethane and polyurethane-polyacrylate hybrid coatings for wood surfaces, a mathematical model, which was originally used to describe carbon dynamics of organic matter in soil, was adopted to analyze the biodegradation test results of a soil burial test with the coating samples. The coating samples were either tested alone or together with wood surfaces, which were incubated in soil for 8-12 weeks. The carbon dioxide liberated by the biodegradation of the samples was collected by 0.5 N NaOH solution every week. An approximate solution of the mathematical model was applied to describe the fraction of carbon loss of the samples as carbon dioxide over time. The results showed that the mathematical model has great potential to improve the objectivity and allow the comparison of biodegradation test results