Morphological characteristics and barrier properties of thermoplastic starch/chitosan blown film

• TPS/CTS films were prepared through blown film extrusion.
• SEM, CLSM and XPS confirmed the distribution and deposition of chitosan on the outer film surfaces.
• A thin chitosan-rich layer on the film surfaces caused improved barrier properties and reduced hydrophilicity.
• Water vapor and oxygen permeability of TPS/CTS films decreased with increasing chitosan concentration.
• TPS/CTS film could potentially be used as an edible film for food and pharmaceutical applications.

Fabrication of starch-based edible film using blown film extrusion is challenging and interesting because this process provides continuous operation with shorter production time and lower energy consumption, is less labor intensive, and results in higher productivity than the conventional solution casting technique. Previously, we reported on the preparation and some properties of thermoplastic starch/chitosan (TPS/CTS) blown films; however, their morphological characteristics and barrier properties had not yet been elucidated. The present work thus aims to investigate the effect of chitosan (0.37–1.45%) on morphological characteristics, water vapor and oxygen barrier properties as well as hydrophilicity of the TPS and TPS/CTS films. The relationship between morphological characteristics and properties of the films was also discussed. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS) confirmed the distribution and deposition of chitosan on the film surface. The existence of chitosan on the surface imparted the improved water vapor and oxygen barrier properties and the reduced surface hydrophilicity to the film. The results suggest that this biodegradable bio-based TPS/CTS film could potentially be used as an edible film for food and pharmaceutical applications.