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Keywords:

  • Biodegradable films;
  • extrusion;
  • film characterisation;
  • mechanical properties;
  • process variables;
  • sorption isotherms;
  • starch–chitosan films;
  • water vapour permeability

Summary

Despite the increased use of extrusion technology in the production of biodegradable films, a better understanding of its effects on the several biopolymers is required. Therefore, the influence of extrusion temperature (120, 130 and 140 °C) and screw speed (25, 35 and 45 r.p.m.) on the properties of an active film formulated with starch, chitosan and oregano essential oil was investigated. Mechanical and barrier properties, apparent opacity and blow-up ratio (BUR) of films were determined. The increase in screw speed had a positive effect on BUR and water vapour permeability (WVP) and a negative effect on opacity, tensile strength and elongation at break of the films. Low die temperatures resulted in decreased tensile strength, elongation at break, Young’s modulus and WVP of the films. Sorption isotherms of films were directly influenced by the extrusion conditions and films produced at 130 °C and 35 r.p.m. were less hydrophilic.