A FTIR study of interfacial interactions between ethylene copolymers and hydrated aluminium surfaces

Author: Strålin Anders   Hjertberg Thomas  

Publisher: Taylor & Francis Ltd

ISSN: 1568-5616

Source: Journal of Adhesion Science and Technology, Vol.6, Iss.11, 1992-01, pp. : 1233-1250

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Abstract

Interfacial interactions to hydrated aluminium were examined for poly(ethylene-co-vinylacetate) EVA, poly(ethylene-co-butylacrylate) EBA, and poly(ethylene-co-acrylic acid) EAA. By means of IR reflection-absorption spectroscopy, the interactions between the effective functional groups were analysed at the polymer/aluminium interface. Thin copolymer films were prepared by solution casting onto aluminium, which had been hydrated by immersion in boiling water. The spectra representing the interface material revealed a strong hydrogen bond interaction between hydroxyl groups on the hydrated aluminium surface and the carbonyl oxygen in the ester group in EVA and EBA. The absorbance mode of the hydrogen bonded carbonyl was displaced to lower wavenumbers and appeared 34 cm-1 and 38 cm-1 below the 'free' carbonyl for EVA and EBA, respectively, which indicates that the hydrogen bond is very strong. For the C-O stretching mode in the ester group, a displacement of 36 cm 1 in the opposite direction was observed, also an effect due to the hydrogen bond to the carbonyl. Furthermore, it was found that the absorptivity for the hydrogen bonded carbonyl was much higher than for the 'free', and for that reason a relative absorptivity ratio between them was determined. For EAA cast onto hydrated aluminium surfaces, the absorbance mode of the carbonyl disappeared, but new peaks arose at lower wavenumbers indicative of a carboxylate. This was explained to be due to a reaction between carboxylic acid groups and aluminium hydroxyl groups on the hydrated surface.