High-performance thermoplastic starch/poly(butylene adipate-co-terephthalate) blends through synergistic plasticization of epoxidized soybean oil and glycerol.

Utilizing starch, an abundant polysaccharide, as the renewable filler to blend with poly(butylene adipate-co-terephthalate) (PBAT) is a feasible tactic to construct cost-effective and high-performance biodegradable materials. It's worth noting that the thermal processing properties of starch can be manipulated by its plasticized behavior. Herein, epoxidized soybean oil (ESO) and glycerol were used as the plasticizer for native corn starch and the plasticized starch was integrated with PBAT to manufacture starch-based biodegradable blend films. ESO breaks the hydrogen bonds between starch chains through the fatty chains grafting reaction and increases the distance between starch molecular chains due to the large molecular weight of ESO. Meanwhile, glycerol molecules are incorporated into the starch molecular chains, and fatty chains grafted starch chains, effectively reducing the intermolecular forces of molecular chains. On account of the synergistic plasticization of ESO and glycerol which possess good compatibility with PBAT, the PSG20E10 blend film achieved a tensile strength, an elongation at break of 16.11 MPa and 612.09 %, and the balanced water and oxygen permeability properties.

Fractionation of technical lignin and its application on the lignin/poly-(butylene adipate-co-terephthalate) bio-composites.

Complex and heterogeneous structures of lignin impede its further conversion and valorization. Herein, three technical lignins (from softwood, hardwood, and grass) were fractionated with acetone solvent to reduce their structural heterogeneity, which were then blended with poly-(butylene adipate-co-terephthalate) (PBAT) to fabricate biodegradable bio-composites. Macromolecular structures of lignins and their effects on the properties of lignin/PBAT composites were thoroughly investigated. Results showed that all fractionated lignin composites displayed better properties. Particularly, the raw and fractionated softwood lignin-based composites exhibited superior performance compared with others. Benefiting from the lower molecular weight, hydroxyl groups, and condensation, acetone fractionated softwood lignin presented the lowest Tg (115.7 °C), achieving ideal melt miscibility and interfacial interaction between lignin and PBAT. The decreased Tg of lignin facilitated the lignin dispersion in the matrix and increase the mechanical strength of the composites. Overall, the fractionated technical lignin possessed desirable physical and chemical structure features, conferring composites good miscibility and mechanical properties.