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Copolyamides based on polyamide-6,6 (PA-6,6) were prepared by solid-state modification (SSM). Para-and meta-xylylenediamine were successfully incorporated into the aliphatic PA-6,6 backbone at 200 and 230 C under an inert gas flow. In the initial stage of the SSM below the melting temperature of PA-6,6, a decrease of the molecular weight was observed due to chain scission, followed by a built up of the molecular weight and incorporation of the comonomer by postcondensation during the next stage. When the solid-state copolymerization was continued for a sufficiently long time, the starting PA-6,6 molecular weight was regained. The incorporation of the comonomer into the PA-6,6 main chain was confirmed by size exclusion chromatography (SEC) with ultraviolet detection, which showed the presence of aromatic moieties in the final high-molecular weight SSM product. The occurrence of the transamidation reaction was also proven by 1 H nuclear magnetic resonance (NMR) spectroscopy. As the transamidation was limited to the amorphous phase, this SSM resulted in a nonrandom overall structure of the PA copolymer as shown by the degree of randomness determined using 13 C NMR spectroscopy. The thermal properties of the SSM products were compared with melt-synthesized copolyamides of similar chemical composition. The higher melting and higher crystallization temperatures of the solid state-modified copolyamides confirmed their nonrandom, block-like chemical microstructure, whereas the melt-synthesized copolyamides were random.

The kinetics of the modification of styrene acrylonitrile (SAN) with aminoethanol to oxazoline‐containing copolymers has been monitored with FTIR spectroscopy. Further, the interfacial reaction in bilayer samples of the oxazoline groups of these copolymers and the carboxylic acid groups of poly(ethylene‐co‐methacrylic acid) (PE‐co‐MA) copolymers has been studied by FTIR at different temperatures. The interfacial formation of ester‐amides has been measured quantitatively by FTIR difference spectroscopy.

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