Study on the preparation and properties of the cast film and biaxially oriented film of biodegradable poly(ethylene adipate‐co‐terephthalate)

Abstract Poly(ethylene adipate‐ co ‐terephthalate) (PEAT), a biodegradable copolyester, is a high‐toughness and low‐cost material, with fracture elongation exceeding 1000%. However, the existing literature still contains few studies on its processing properties. In this study, the processing properties of PEAT with characteristic viscosities of 0.8 and 1.0 dL/g, respectively, were systematically compared. The thermal stability, rheological behavior, and degradation properties of the cast film (CFPEAT) produced by those two were compared. As well as the effects of different stretching temperatures on the mechanical and crystalline properties of biaxially oriented PEAT film (BOPEAT)were also studied. The results showed that PEAT with the characteristic viscosity number of 1.0 dL/g had better performance and that the BOPEAT film exhibited superior performance when the tensile temperature was 70°C. The tensile strength increased from 29.44 to 41.35 MPa for CFPEAT, which increased about 40.46%, and the elongation at break was 390.88%. The XRD results revealed that biaxial stretching primarily improved the film's performance through strain‐induced crystallization. The results of degradation experiments showed that PEAT had excellent degradation properties, and under alkaline environments, the degradation rate was faster. Highlights PEAT has excellent toughness and degradation properties. PEAT with the characteristic viscosity of 1.0 dL/g has better performance. BOPEAT is more rigid.