ADHESION BETWEEN HYDRATED ALUMINUM AND ETHYLENE COPOLYMERS CONTAINING METHOXY SILANE GROUPS

The peel strength between ethylene copolymers and aluminium has been investigated.The polymers were ordinary LDPE, copolymer with butyl acrylate (EBA), copolymer with vinyltrimethoxysilane (EVS), and copolymer with both comonomers (EVSBA). The aluminium was modified by hydration in boiling water up to 120 s. The strength of melt-pressed laminates was tested with a T-peel test and the failure mechanism was evaluated by FTIR and SEM. The hydration leads to a porous pseudoboehmite with an increased content of Al-OH groups, which causes considerable increases in peel strength for all polymers, in particular for EVS and EVSBA. The mode of failure varied between adhesive and cohesive depending on the surfaces. The introduced porosity contributes with mechanical keying while the Al-OH groups enable polar interactions for EBA and the formation of interfacial covalent bonds for EVS and EVSBA.