Properties and Nanocomponent Migration of Poly (butyleneadipate-co-terephthalate) Nanocomposite Film under Ultraviolet Irradiation

To investigate effect of ultraviolet (UV) irradiation on the properties of poly (butyleneadipate-co-terephthalate) (PBAT), the properties of PBAT/nano-ZnO and PBAT/nano-TiO₂ composite films subjected and not subjected to UV irradiation, and the migration of nano-components from them to 3 g/100 mL acetic acid were studied. Meanwhile, the composite films were characterized by attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The results showed that the addition of each nanoparticle had little effect on the barrier performance of the composite film without UV irradiation. With the addition of nano-ZnO, the tensile strength of the composite film decreased by 22.88%-40.99%, the elongation at break decreased to 86.07%-90.98% of that of pure PBAT films, and the maximum migration of nano-ZnO was 11.82 mg/kg. The addition of nano-TiO₂ had little effect on the tensile strength, but decreased the elongation at break to 73.48%-87.18% of that of pure PBAT films, and no migration of nano-TiO₂ was observed (the detection limit of the method used was 0.009 mg/kg). With an increase in UV irradiation time, the elongation at break and tensile strength of the composite films decreased gradually, but the mechanical properties of the PBAT/nano-ZnO films decreased less than those of the pure PBAT and PBAT/nano-TiO₂ films at the same irradiation time. After two days of UV irradiation, the oxygen permeability coefficient of the composite films increased significantly (P < 0.05), while the moisture permeability coefficient changed little. The maximum migration of nano-ZnO was 16.66 mg/kg, whereas no migration of nano-TiO₂ was detected. The ester bond of the composite films was broken, the crystallinity reduced, and the surface became rough, with holes in it. We concluded that UV irradiation destroys the structure of PBAT composite film and degrades its properties. Nano ZnO can inhibit the decline of the mechanical properties of PBAT composite film to a certain extent, but its migration increases gradually.