Enhanced thermal stability, toughness, and electrical conductivity of carbon nanotube-reinforced biodegradable poly(lactic acid)/poly(ethylene oxide) blend-based nanocomposites

Carbon nanotube (CNT) was incorporated into the miscible poly(lactic acid)/poly(ethylene oxide) (PLA/PEO) blend to successfully fabricate biodegradable nanocomposites. Scanning electron microscope images revealed the well dispersion of as-received CNT within the blend through the melt-mixing process. Thermogravimetric analysis showed that the CNT significantly improved the thermal stability of the blend (up to 68 °C increase at 3-phr CNT addition compared to the blend at 10 wt% loss) in air. Differential scanning calorimetry data showed the nucleation effect of CNT on the crystallization of individual PLA and PEO; the presence of CNT increased the melting temperature of PLA crystals. Measurement of rheological behavior confirmed the formation of CNT (pseudo-)network structure in the composites. The impact strength of the composite with 3-phr CNT loading was three times higher than that of the blend. The electrical resistivity of the blend reduced by up to nine orders of magnitude at 3-phr CNT loading. The electrical and rheological percolation thresholds were both achieved at 1-phr CNT loading for the nanocomposites.