2003 Volume 52 Issue 3 Pages 319-324
Two series of copolymers, Poly (RAAm-co-ST) and Poly (BMAAm-co-R'MA), as the novel primers in adhesive bonding polypropylene (PP) were prepared by radical copolymerization of alkoxymethyl acrylamide (RAAm) and styrene (ST) or alkyl methacrylate (R'MA). Alkoxy groups (OR) in the RAAm moieties used were methoxy, ethoxy, isobutoxy and butoxy, whereas alkyl groups (R') in the R'MA moieties were methyl, ethyl, isopropyl, isobutyl, n-butyl and n-hexyl. Homopolymer of RAAm, Poly (RAAm), was also prepared and characterized: the glass transition temperature of Poly (RAAm) was Tg=76.8-70.0°C and Poly (RAAm) was thermally decomposed through a two step degradation with the evolution of corresponding alcohol. The bonding properties of PP, using two series of copolymers as primers, were studied by measuring the shear strength (τ) of single-lap joints between PP and PP or other substrates such as polyethyleneterephthalate (PET), nylon 66 (66N), alminium, steel and glass. The primers tested were effective when used with polyurethane adhesive. Mixed substrate bonds prepared between PP and others gave substantial bond strength (τ=48.4-51.3MPa) in comparison to bond strength for unprimered controls (τ=8.9-16.7MPa). Maximum bond strength was obtained when Poly (BMAAm-co-HMA) was chosen as a primer. The mechanism for the adhesive bonding of PP was discussed.