Preparation and characterisation of biodegradable polylactic acid/ethyl cellulose film produced using the extruder and roller mixer machine

The present study aimed to produce polylactic acid (PLA) and ethyl cellulose (EC) biodegradable film using a single screw extruder and a roller mixer machine. This method resulted in better mixing of the polymers, reducing the possibility of burns and easier control of the film thickness. The mechanical properties measurement showed that tensile strength (TS) decreased by about 37.9%, and elongation at break (EAB) increased about 2.6-fold by increasing EC to 75%. The increase in EAB indicated the plasticising effect of EC. Since flexibility is essential in shaping a material without fracture, PLA/EC blend films can be a good candidate for packaging. According to DSC results, glass-transition temperature (T_g) decreased in the blend films, probably due to the increase in the hydrophilicity of the films after EC addition. The water contact angle of pure PLA film was about 83°, whereas it reached 28° in the film containing 75% EC. The water vapour permeability of PLA film was 2.24 × 10⁻¹¹ g m.s.Pa⁻¹ and PLA reduction to 25% increased the WVP by about two times. Adding EC into the pure PLA film reduced the transparency, indicating the potential of blend film for the packaging of light-sensitive food products. Besides, EC addition enhanced PLA biodegradability after enzymatic treatment (alcalase) and soil burial.