Improving the ductility, toughness, and electrical conductivity of poly(lactic acid) by forming poly(lactic acid)/thermoplastic polyester elastomer blend and blend-based nanocomposites

In this study, poly(lactic acid) (PLA)/thermoplastic polyester elastomer (TPEE) (70/30) blend and blend-based nanocomposites with carbon nanotube (CNT) as a nanofiller were fabricated by conventional melt mixing. Scanning electron microscopy results showed that the blend had a biphasic morphology, and CNTs were selectively distributed in the dispersed TPEE domains in the composites. The presence of CNTs induced the agglomeration and shape modification of TPEE domains, consequently influencing the examined properties. Differential scanning calorimetry results revealed that the crystallizability of PLA was improved after blending with TPEE, and further CNT incorporation increased the crystallization temperature of TPEE during cooling. The elongation at break (EB) and notched impact strength (IS) of PLA were evidently improved in the blend and composites. In particular, the EB and IS in the composites increased by up to 290% and 43%, respectively. The electrical resistivity of neat components and the blend decreased by up to eight orders of magnitude after 3 phr CNT loading due to double percolation in TPEE domains and dispersed CNTs. A percolation threshold at ca. 1 phr CNT loading for electrical conductivity was determined. Rheological property analysis suggested the formation of a pseudo-network structure, which was attributed to the CNTs increasing the viscosity of the TPEE domains in the composites.