Photocrosslinking of elastomer systems. II. Ultraviolet light‐induced reactions in an EPDM modified by grafting of benzoin derivatives

Photocrosslinking experiments were performed on elastomeric polymer films (EPDM) previously modified by grafting a photosensitive initiator (benzoin derivative) onto the macromolecular backbone. This modification was performed by a series of Friedel–Crafts reactions and the resulting materials were characterized by infrared (IR) spectroscopy in conjunction with model reactions. After ultraviolet (UV) irradiation the photocrosslinked samples were studied by IR spectroscopy in conjunction with the measurement of physical properties. It apperared that grafting the photosensitizer onto the elastomer considerably enhances the crosslinking reaction even with a limited quantity of grafted benzoin derivative. Moreover, the results obtained suggest that the structure of the resulting networks is strongly dependent on the crosslinking process used; that is, curing the elastomer with peroxide or UV irradiation either of a blend of elastomer and photosensitizer or of the same elastomer modified by grafting the chromophore.