Destruction of metal-resin adhesion due to water penetrating through the resin

• DOI: 10.1007/bf02403808
• Publication Date: 2006-05-22T09:20:04Z
• Authors: H. Ohno; K. Endo; Y. Araki; S. Asakura
• Keywords: 02 engineering and technology; 0210 nano-technology

Polymethyl methacrylate (PMMA) film bonded by 4-META dental adhesive resin to mild steel was used as a specimen to study the mechanism of water permeation into the adhesive interface. Degradation of the adhesion interface after immersion in water was investigated by measurement of peeling area after imposing thermal stress using liquid nitrogen. The amount of water penetrated at the interface was calculated from the solution to Fick's second equation. The degradation at the interface is discussed with respect to the water content. Water enters the interface by diffusion through the resin rather than by passage along the interface. The interface is broken by water when the water content at the interface reaches 48% of the equilibrium water concentration of PMMA. Observation through the PMMA film shows no change in the mild steel surface at 48% equilibrium water concentration; at 95% water content many small white spots appear on the surface. The surface colour gradually changes to black due to the formation of corrosion products.