Effect of the processing methods on the performance of polylactide films: Thermocompression versus solvent casting

Polylactide (PLA) films were prepared by the thermocompression and solvent‐casting methods, and selected properties, such as the mechanical, water‐vapor‐barrier, thermal, and thermomechanical properties, were tested. The solvent‐cast films contained 13.7% solvent, which functioned as a plasticizer, as evidenced by the results of the measurements of dry matter and thermogravimetric analysis as well as dynamic mechanical analysis. The PLA films prepared by the thermocompression method were strong and brittle, with maximum tensile strength (σ max ) and maximum elongation at break (ϵ max ) values of 44.0 ± 2.2 MPa and 3.0 ± 0.1%, respectively; however, the solvent‐cast films were more ductile, with σ max and ϵ max values of 16.6 ± 1.0 MPa and 203.4 ± 20.8%, respectively. The water vapor permeability of the PLA films was lower than that of plastic films such as low‐density polyethylene and high‐density polyethylene but higher than that of commonly used biopolymer films. In addition, both types of tested PLA films were water‐resistant and not soluble in water. The thermocompressed films showed higher thermal stability than the solvent‐cast films.