Polyurethane prepolymer-modified high-content starch-PBAT films

•Starch-PBAT films with high starch content were successfully blown on a large scale.•Hydrophobicity was increased by the interaction between polyurethane prepolymer and starch.•Amylose contents of starch have a different effect on the performance of films. We report a modified starch-poly(butylene adipate co-terephthalate) (PBAT) film (MSPF) prepared by extrusion blowing. Polyurethane prepolymer (PUP), was modified to the starch to enhance the compatibility. Different contents of amylose was blended with PBAT for improving mechanical strength and oxygen-barrier properties of MSPF. The microstructures, crystallinity, mechanical properties, oxygen-barrier capacity of MSPF were thoroughly evaluated. The result showed that MSPF with high starch content and excellent performances was successfully prepared with the synergy of PUP modification, amylose introduction and extrusion blowing. The crystallinity, hydrophobicity, oxygen-barrier properties and mechanical properties of MSPF increased with the increasing amylose content. The maximum tensile strength and elongation at break of MSPF reached 10.6 MPa and 805.6 %, respectively, even at the high starch content of 50 %. The result demonstrated that MSPF having excellent mechanical properties and oxygen-barrier properties could be use in the biodegradable field such as packaging materials, agricultural films and garbage bags.