(154e) Injection Molded Solid And Microcellular Polylactide-Carbon Nanotube Nanocomposites
Poly(lactide) (PLA)-multiwalled carbon nanotube (MWCNT) nanocomposites were melt-compounded using a twin-screw extruder. Solid and microcellular tensile bar specimens were produced via conventional and microcellular injection molding processes, respectively. Various characterization techniques were applied to study the static and dynamic mechanical properties, degree of MWCNT dispersion, cell morphology, and crystallization behavior. The addition of a small amount of MWCNTs led to a decrease in the cell size and an increase in the cell density of the microcellular PLA. A transmission electron microscopy analysis of the PLA-MWCNT specimens revealed a higher degree of MWCNT dispersion in the microcellular PLA-MWCNT composite compared with its solid counterpart indicating the microcellular injection molding process further dispersed the MWCNTs. While the addition of 1.5 wt% MWCNTs slightly increased the average specific modulus of the microcellular PLA, it did not affect the average specific modulus of the solid PLA. In addition, for both solid and microcellular specimens, the specific strength, specific toughness and strain-at-break decreased with the addition of MWCNTs. The storage modulus was not affected significantly with the addition of MWCNTs, but was found to be higher for the microcellular specimens compared with their solid counterparts. Finally, the crystallinity of PLA increased significantly with the addition of MWCNTs.