Synthesis and characterization of copolyamide 1010/410 with varying putrescine contents for meat packaging applications

Abstract

Acting on the Bioeconomy strategy, this study has developed fully bio-based copolyamide 1010/410 (PA1010/410) from “nylon salts” derived from renewable putrescine, decamethylenediamine, and sebacic acid monomers. Different fully bio-based copolyamides were synthetized by the polycondensation reaction of nylon 1010 salt with 12.5, 25, and 37.5 mol% of nylon 410 salt. Thereafter, the resultant PA1010/410 grades were shaped into 150-µm films by thermo-compression and characterized. Results showed that the putrescine content presents a strong influence on the molecular weight, crystallinity and, hence, thermal, mechanical, and barrier properties of PA1010/410. In particular, it was observed that the introduction of nylon 410 contents at 25 and 37.5 mol% resulted in PA1010/410 grades in the 2–3 × 10⁴ g mol⁻¹ range, with a crystallinity as low as ∼15%. Interestingly, these copolyamide compositions led to transparent films melting at nearly 180 °C, being highly ductile with elongation at break of up to 130% and improved barrier to oxygen with a permeability as low as 5.3 × 10⁻¹⁹ m³ m m⁻² Pa⁻¹ s⁻¹. These green nylons were finally applied as lid films in trays to preserve beef meat, and were shown to successfully extend food shelf life beyond those of current commercial monolayer solutions based on petrochemical polymers, thereby showing their potential for use in sustainable food packaging.