Low pressure and low temperature synthesis of polyamide-6 (PA6) using Na⁰ as catalyst

The synthesis and use of plastic materials in several industrial areas has been increasing rapidly in the last century. Among the known plastics, the polyamides have excellent mechanical properties as high strength and wear resistance. This study reports a novel bath synthesis process to obtain polyamide-6 (PA6) from ε-caprolactam using metallic sodium as the catalytic agent in an inert atmosphere of N₂. During the synthesis process that was proposed, contrary to conventional industrial processes which involve the use of high pressures, the reaction was carried out at atmospheric pressure. The conversion degree was ~90-95% and the degree of crystallinity was 36%; the mechanical properties like tensile strength and Charpy impact obtained were similar to that previously reported in the literature.