Properties of polylactic acid-modified lignin biocomposites

Polylactic acid (PLA) is a thermoplastic biodegradable polymer that can be made from annually renewable resources. Lignin is a natural amorphous polyphenolic macromolecule inexpensive and easily available. In the present study PLA and acetylated lignin (L) biocomposites were prepared by casting from chloroform solution. PLA can crystallize from the melt in the ? and ?' forms, depending on the adopted crystallization conditions. During the PLA annealing the transformation from ?' to ? occurs via solid phase transition. The presence of the lignin in the biocomposites interferes with the crystal transformation process. Isothermal crystallizations were performed at different temperatures, the presence of lignin causes an increase of the time of crystallization, while the overall crystallization rate and the spherulite radial growth rate decrease with enhancing the lignin content in the biocomposites. The thermal decomposition temperature decreases with increasing the lignin amount, while the char yield is proportional to the biofiller content.