Characterization of structure and properties of thermoplastic potato starch film surface cross‐linked by UV irradiation

Abstract Ultraviolet (UV) irradiation is an environmentally friendly technique to modify starch. In this study, potato starch films were irradiated by UV (wavelength ∼302 nm) in the presence of sodium benzoate as a photo‐sensitizer (PHS). PHS concentrations in the starch films were varied in the range of 0.2–1.0% (based on dry starch). Cross‐linking reaction was initiated by UV irradiation and proven by gel mass and swelling degree measurement when immersed in DMSO. The modified starch film was characterized by attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR) to investigate the changes of the surface properties with UV irradiation over time. Water contact angle and Tq of starch film were measured to understand the influence of the UV modification. The result showed that water contact angle and Tq of the cross‐linked starch film increased with the dosage of UV irradiation.