Revealing the Microstructural Evolution under the Blown Film Processing for PBAT Materials

A PBAT film is generally fabricated through blown film processing, during which the thermal-force fields strongly regulate the final performance. However, the underlying mechanism remains unclear because there is little quantitative analysis due to the high blowing speed. Here, a self-developed blown film system equipped with an infrared thermal camera is used to monitor the temperature, and both the blow-up ratio and the take-up ratio are used to regulate the magnitude of the force field. The results show that a dominant transverse force field promotes isotropic lamellar crystal formation, resulting in mechanical isotropy with excellent water barrier properties. Conversely, a stronger vertical force field enhances the molecular chain orientation, leading to mechanical anisotropy with enhanced strength. Additionally, the steep temperature gradients amplify the regulatory force fields. These findings may provide guidelines for optimizing processing parameters to achieve the targeted macroproperties of PBAT industrially.