Effect of the γ ∗ → α-structural transition, occurring in the presence of mineral acids, on the molecular mobility and relaxation processes in polyamide-6

Abstract

In the temperature range 77–520 K, the dynamic shear modulus and the tangent of the mechanical loss angle were measured for PA-6, with crystallites either in the form of γ ∗- or α-crystalline modifications, or of their mixture. The structural γ ∗ → α-transition, occurring in PA-6 crystallites in the presence of aqueous nitric acid solution, is accompanied by an increase in the ordering of macromolecular segments in noncrystalline domains, by a shift of the devitrification limit to a high temperature range, and by an increase in the diffusion coefficient.