COMPREHENDING COATING ADHESION: PART 1:TO STICK OR NOT TO STICK?

摘要

The inability of an epoxy coating to stick to a surface such as polyethylene, for example in a pipeline field joint coating, is puzzling to coating specialists used to their excellent adhesion to most other surfaces. This paper looks at surface energy properties of coatings and how this can explain such behaviour. It also explains why abrasive blasting such surfaces can make adhesion worse and how surface oxidation can be used on such low energy surfaces can improve properties. Pressure sensitive adhesives, such as tapes and shrink sleeves, can be used on low energy surfaces because their viscosity and mechanical properties enable them to provide good bonding. Finally, there is a brief review of methods used to measure adhesion of coatings, pointing out their limitations especially regarding the inability of test results to relate to actual interfacial adhesion.