AFM investigation of the influence of ethanol absorption on the surface structure and elasticity of polyamides

We study the variations of surface structure and elasticity of different types of Nylon during absorption of ethanol using AFM surface topography and AFM micro-mechanics. We observe that ethanol absorption induces significant changes in the surface structure, in particular an increase of roughness as well as the presence of local damage. All investigated Nylons soften by a factor 1.5-2.5 as a consequence of ethanol absorption. The Young modulus of the samples as a function of immersion time shows a complex, non-monotonic behavior with a minimum at intermediate immersion times. This behavior results from an interplay between the reduction of the glass transition temperature T-g, typically observed in bulk, and surface-specific effects such as the onset of surface crystallisation and degradation.