Effect of Soft Segment Molecular Weight in Poly(ε‐Caprolactone)‐Based Polyurethane Prepolymer on the Structure and Properties of <scp>PBAT</scp>/Potato Starch Composites

ABSTRACT Poly(butylene adipate‐co‐terephthalate) (PBAT) is a common biodegradable material that has attracted attention due to its excellent performance. However, its application is limited due to high costs. Therefore, this work chooses cost‐effective and readily available biomass resource‐potato starch (PS) as filler, with PBAT as the matrix, to prepare an inexpensive, environmentally friendly, and biodegradable PBAT/PS composite material. To address the interfacial incompatibility between PBAT and PS, a reactive compatibilizer, polycaprolactone‐based polyurethane prepolymer (PCLPU), is employed, and the effect of the molecular weight of the soft segment of PCLPU on the structure and properties of the PBAT/PS composite material is studied. By conducting infrared spectroscopy analysis and scanning electron microscopy tests to observe changes in the interfacial structure, combined with the variation in mechanical properties, it is found that as the molecular weight of the soft segment of PCLPU decreases, the properties of the composite material are further improved. Among them, PCLPU with a soft segment molecular weight of 500 g·mol −1 has the best effect when modifying the PBAT/PS composite material, with the elongation at break and tensile strength reaching 55.7% and 15.4 MPa, respectively.