Chemical bond strain in molecules of polyamide 6 coatings on the steel surface

Abstract

The structure and stresses of chemical bonds in a 20 μm thick polyamide 6 (PA 6) coating on the steel surface are studied by IR spectroscopy. It is found that PA 6 molecules in the coating are oriented parallel to the metal surface and the content of metastable crystalline (γ) and mesomorphic (β) phases in it is twice as low as in PA 6 films. In the crystalline α phase, the molecular skeleton is compressed and “lateral” (respective to the skeleton) chemical bonds are extended. In the mesomorphic β phase, the concentration of overstressed (extended to a prerupture state) parts in the molecular skeleton is higher than in the film. These effects are explained by a change in the PA 6 low-frequency vibration spectrum at the PA 6-metal interface.