Fabrication and characterization of polylactide/polyethylene glycol/Chlorella vulgaris biocomposite films

Biocomposite films were produced by blending Chlorella vulgaris (CL) at selected concentrations (5–15% wt. basis) with 10% polyethylene glycol (PEG) and polylactide (PLA) using a twin-screw extruder. The mechanical, microstructural, thermal, barrier, and rheological properties of the composite blends were examined to evaluate their compatibility and property enhancement. As the CL concentration increased from 5% to 15% in the PLA/PEG blend, there was a significant decrease in mechanical, thermal, and rheological properties, indicating a degradation in the biopolymers. Surface morphology and phase imaging revealed heterogeneity in the composite film surfaces. Thermogravimetric analysis revealed lower maximum degradation temperatures (≅ 60 °C), whereas DSC revealed that CL acted as a nucleating agent, significantly reducing the melt crystallization temperature. The water vapor transmission rate increased with CL incorporation, whereas FTIR and XRD analysis revealed no significant changes in the composite films. The study suggests that substituting up to 10% of PLA is techno-economically feasible for producing composite films, and the addition of a suitable compatibilizer can enhance interactions between the matrix and filler.