Electrical and mechanical properties of poly(L-lactide)/carbon nanotubes/clay nanocomposites

An organoclay containing epoxy groups, twice-functionalized organoclay (TFC), was synthesized by reacting (glycidoxypropyl)trimethoxy silane with Cloisite25A (C25A), which had already been modified with an amine compound. The introduction of epoxy groups to the clay surface and carboxylic group-functionalized multiwalled carbon nanotubes (MWCNTs) improved the interfacial adhesion between the poly(L-lactide) (PLLA) and nano-sized fillers when melt-compounded. The PLLA/MWCNTs/TFC nanocomposites showed superior tensile properties to those of PLLA and PLLA/CNTs. The dispersion of MWCNTs in the PLLA matrix decreased the electrical resistivity of the composite substantially due to the higher MWCNT loading. However, the introduction of TFC to the PLLA/MWCNTs nanocomposites resulted in a slight increase in volume resistivity. This increase was attributed to the individual MWCNTs being blocked by the TFC. The clays in the PLLA/MWCNTs/TFC nanocomposites prevented direct contact between the neighboring MWCNTs, which increased the electrical resistivity of the nanocomposites.