Influence of cellulose nanofibers on the morphology and physical properties of poly(lactic acid) foaming by supercritical carbon dioxide

The foaming process of poly(lactic acid) (PLA)/cellulose nanofiber (CNF) nanocomposites using supercritical CO2 as a foaming agent was studied with various CNF contents. CNFs were obtained by sonication, and their morphology was examined by transmission electron microscopy. According to the CNF content, the changes in the rheological and the thermal properties of the nanocomposites were studied through viscometry and differential scanning calorimetry. The viscosity of the composites increased with increasing CNF content. The effects of the CNF content on the foam properties and morphologies were evaluated. Compared to neat PLA foam, the PLA/CNF nanocomposite foams exhibited decreased cell size as well as increased cell density and foam density due to the improved viscous properties.