Morphology and properties of electrically and rheologically percolated PLA/PCL/CNT nanocomposites
Résumé
Poly(lactic acid)/poly(ɛ-caprolactone)/carbon nanotube (PLA/PCL/CNT) nanocomposites (NCs) were melt-processed in a conventional industrial-like twin-screw extruder maintaining a constant PLA/PCL 80/20 wt. ratio. CNTs located in the thermodynamically favored PCL phase and, as a result, the “sea–island” morphology of the unfilled blend was replaced by a more continuous PCL dispersed phase in the ternary NCs. Rheological and electrical percolation took place at the same CNT contents (over 1.2 wt %) that TEM images suggest continuity of the PCL phase. The electrical and the low-strain mechanical behaviors upon CNT addition were similar in the reference binary PLA/CNT and ternary PLA/PCL/CNT NCs. In the percolated NCs, the conductivity became 106–107 times higher than in the insulating compositions, while the Young modulus increased linearly upon the addition of CNT (12% increase at 4.9 wt % loading). Moreover, all the PLA/PCL/CNT NCs showed a ductile behavior (elongation at break >130%) similar to that of the unfilled PLA/PCL blend (140%), in contrast to the brittle behavior of binary PLA/CNT NCs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45265. © 2017 Wiley Periodicals, Inc.