City Research Online

Abstract

One of the main causes of premature failure of paint films is poor adhesion to substrate arising from the presence of contaminants at the interface. Chemical or mechanical treatment of the substrate is normally used to ensure reasonable cleanliness of the surface, but in practice some contamination usually remains. Paints designed to accommodate such contamination would ensure that failures arising from this cause would be reduced.

In this work the effect of modifying the polymer structure with minor amounts of nitrogen-containing groups, or a combination of those with carboxyl groups, has been studied in relation to the level of adhesion attained on deliberately contaminated surfaces. Generally, improved adhesion has been achieved with both thermoplastic and thermosetting solvent-thinned acrylic paints and also with emulsion-type acrylic paints by such modification.

It is suggested that the mechanism of adhesion is of a chemical nature. This is based on the chemical reaction and the detection of an intermolecular compound between the monomeric form of the nitrogen-containing compound and the contaminant. It was concluded that similar behaviour would occur between the polymer carrying such a compound and the contaminant.

An examination of the effect of structural changes of the polymeric chain on the critical surface tension and cohesive energy density of the polymer and their relation to adhesion showed that the level of modification was too small to introduce any significant changes in these properties.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry T Technology > TP Chemical technology
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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