Abstract
A series of polyester/melamine clearcoat films with varying amounts of melamine crosslinker, and prepared under a range of cure conditions, has been exposed to high intensity UV radiation at cryogenic temperatures in nitrogen, under stress in nitrogen, and in an oxygen-containing atmosphere. The free radicals produced were detected, analysed and quantified by ESR spectroscopy. The results show that the type and concentration of radicals produced is critically dependent on film composition, cure conditions (oven temperature and dwell time), the atmosphere under which photolysis is conducted (N 2 or N 2+O 2), and the extent of mechanical deformation. At the optimum crosslinker concentration and optimum cure conditions, free radical yields were minimised, suggesting that free chain ends are the main photolabile species. New radical species, and significantly increased radical yields, were found in photolysis of samples with a greater than optimum concentration of crosslinker subjected to mechanical strain. In an oxygen-containing atmosphere, peroxy radicals were produced, the direct detection of which is reported here for the first time.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
