Effect of <scp>ChCl</scp> : <scp>MEA DES</scp> Ratio on Plasticization and Performance of Thermoplastic Starch/Lignin Blends

ABSTRACT The influence of the choline chloride:monoethanolamine (ChCl:MEA) deep eutectic solvent (DES) ratio (1:2–1:5) on corn‐starch/lignin blends processed by twin‐screw extrusion is systematically mapped. With increasing MEA content, coherent composition‐dependent responses are obtained: tensile strength ( σ t ) is reduced while elongation at break ( ε b ) is increased; stabilized torque is reduced and melt flow index (MFI) is increased; the glass transition temperature ( T g ) and water contact angle are decreased. Ratio‐dependent red‐shifts and attenuation in the O–H/N–H region are observed by FTIR, together with losses in aromatic and carbonyl bands, consistent with DES–polymer hydrogen bonding and partial lignin solvation. Reduced short‐range order and mid‐range crystallinity are indicated by XRD. To prioritize deployability, a multi‐criteria decision screen is applied (targets: σ t ≥ 1.0 MPa; MFI 3–5 g/10 min; T g ≤ 60°C; contact angle 50°–75°; CrI 15%–30%). A ChCl:MEA ratio of 1:4 is uniquely identified as satisfying all targets simultaneously ( σ t : 1.09 MPa, ε b : 197%, MFI: 3.68 g/10 min, T g ≈ 40°C, contact angle ≈52°, CrI ≈ 22%), whereas 1:5 is over‐plasticized. Ratio tuning of ChCl:MEA is thus established as a single‐parameter, green approach for matching flexibility, processability, and surface activity, yielding a practical operating point for film/sheet bioplastics.