Organically modified rectorite toughened poly(lactic acid): Nanostructures, crystallization and mechanical properties

To improve the toughness of PLA, poly(lactic acid) (PLA)/organically modified rectorite (OREC) nanocomposites were prepared via the melt-extrusion method. A partially exfoliated and partially intercalated structure was confirmed by WAXD and TEM. The crystallization behaviors of neat PLA and nanocomposite were studied by POM and DSC, and it was found that OREC had a great effect on the overall crystallization rate and spherulitic texture of PLA. The presence of OREC could toughen PLA greatly. For example, when 1 wt.% OREC was added, the elongation at break of the nanocomposite was increased to 210%. The toughening mechanism was analyzed through the observation of the inner structure of the tensile test bar using SEM.

This figure illustrates that 0.5∼1 wt.% OREC were intercalated into the PLA matrix, and even some fragments of OREC layers were exfoliated from the silicate crystallites as a result of the high shear stress in the processing. When its content was increased to 5 wt.% there are some agglomerations in OREC.Figure optionsDownload as PowerPoint slide