Transamidation in Melt-Mixed Aliphatic and Aromatic Polyamides. 2. Molecular Characterization of PA 46/PA 6I Blends as a Function of the Extrusion Time, Extrusion Temperature, and Blend Composition

Abstract

The structure of polyamide 46/polyamide 6I copolymers obtained by reaction in the molten state is analyzed as a function of the extrusion time, the extrusion temperature, and the overall blend composition by 13C NMR. The degree of transamidation, the degree of randomness, and the number-average block length of the copolymers are calculated using the method for a four-component polyamide system. It is shown that the transamidation processes are occurring very fast during the first period of melt-mixing but are slowing down at longer extrusion times. High extrusion temperatures affect the transamidation processes in an increasing way. From 13C NMR experiments on PA 46/PA 6I copolymers with different compositions, differences in reactivities are observed. The change of the molecular structure of the copolyamides as a function of the processing conditions and the overall blend composition strongly affects their crystallization behavior.