EFFECTS OF DIPHENYLAMINE AND BINARY SENSITIZERS ON PHOTOGRAFTING OF METHACRYLIC-ACID ON LOW-DENSITY POLYETHYLENE FILM

Photografting of methacrylic acid on low-density polyethylene film (thickness = 30-mu-m) in aqueous medium was examined at 60-degrees using diphenylamine (DPA) as sensitizer previously coated on the film. DPA as well as triphenylamine acted as photofragmenting initiator for the grafting and gave higher extent of grafting and lower formation of homopolymer than triphenylamine. Binary sensitizers, composed of DPA and acceptors such as tetracyanoethylene, 7,7,8,8-tetracyano-quinodimethane, p-chloranil and maleic anhydride, led to higher extent of grafting and lower yield of homopolymer than DPA alone. DPA and acceptor seemed to form a 1 : 1 complex according to study of u.v. spectra. It was found that photografting using the binary sensitizers proceeds effectively through the formation of complex between DPA and acceptor, and that the binary sensitizers are useful for enhancing the ratio of grafted polymer to homopolymer.