Strengthening the Junction Between EPDM and Aluminium Substrate via Plasma Polymerisation

High interfacial strengths of elastomer to metal joints imply the formation of covalent bonds at the interface. It is proposed to deposit a plasma polymer coating containing double bonds on an aluminium substrate for the formation of crosslinks between the elastomer and the coating during peroxide crosslinking of the elastomer. Ethylene-co-propylene-co-diene terpolymer (EPDM) is considered here. Maleic anhydride is polymerised and reacted with allylamine to lead to an amide functionalised plasma polymer which is heated to produce imide functional groups. Plasma polymer coated aluminium/EPDM joints were evaluated by a peel test and the locus of failure was identified by several techniques: SEM, infrared spectroscopy, wettability, and XPS.