Abstract
Abstract Care has to he taken in choosing antioxidants for use in transparent natural rubber vulcanizates since some amines commonly employed as protective agents against thermal degradation photosensitize aging in ultraviolet (uv) light. Further studies using the technique of stress relaxation, undertaken in order to find the most satisfactory type of antioxidant for protection against sunlight aging, have shown that, with additives introduced into extracted samples of peroxide vulcanizate by swelling from ethyl acetate solution, the best results were obtained using a mixture of a substituted bis-phenol and an absorber of uv light. Hitherto, nickel isopropylxanthate (NPX) has been regarded as the most potent protective agent against light; however, the rate of degradation in the presence of NPX was unchanged by the addition of uv absorber and the mixture of bis-phenol and absorber was markedly more effective. Furthermore, the nickel salt is green, whereas the bis-phenols are relatively nonstaining. The work described here is an evaluation of vulcanizates in which the phenol and absorber have been incorporated before cure. The phenol employed was 2,2′-methylene-bis(4-methyl-6-tert-butyl phenol) (Antioxidant 2246 of the American Cyanamid Co.) and the absorber was Tinuvin P (a product of undisclosed formula marketed by Geigy Ltd.), chosen since it protected better in the absence of antioxidant than two other commercial absorbers. Two types of transparent vulcanizate were examined, one being an accelerated sulfur cure and the other a dicumyl peroxide cure. The recipes were as follows:
Published Version
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.
