Amine‑rich deep eutectic solvents for cassava thermoplastic starch: composition‑dependent structure–property mapping and aging resistance
摘要
Cassava‑based thermoplastic starch (TPS) is biodegradable yet constrained by brittleness, moisture sensitivity, and retrogradation. This study evaluates an amine‑rich deep eutectic solvent, choline chloride: monoethanolamine (ChCl: MEA, 1:2–1:5), as a dual plasticizer–compatibilizer for cassava TPS. Films (about 3 mm) were produced by twin‑screw extrusion and compression molding and benchmarked against glycerol‑plasticized TPS and a urea‑based DES (ChCl: urea, 1:2). ChCl: MEA markedly improved processability and properties: melt‑flow index increased from 1.02 to 2.36 g/10 min, glass‑transition temperature decreased from 72.4 to 36.8 °C, crystallinity index fell from 23.7% to 16.1%, thermal stability rose (286 °C to 320 °C), and water contact angle increased from 42° to 71.5°. The 1:3 composition achieved balanced mechanics (tensile strength 2.3 MPa; elongation 184%) and retained approximately 88% strength and approximately 81% elongation after 56 days at 23 °C/50% RH, outperforming glycerol (about 50% retention). All observed improvements were statistically significant (p < 0.05). Overall, the amine‑rich ChCl: MEA DES affords superior plasticization and aging resistance relative to glycerol and urea‑based DES, advancing cassava TPS toward robust, biodegradable packaging applications.