Solution-catsed poly (lactic acid)/stereocomplex polylactide/CNT composite films preparation and properties

In this study, solution casting was employed to prepare poly(lactic acid) (PLA)/stereocomplex polylactide(sc-PLA)/carbon nanotube (CNT) composite films. The sc-PLA microspheres, and CNT composite films were characterized using various techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The size and crystallinity of the sc-PLA microspheres were strongly influenced by the molecular weight of PLA, while functionalizing CNT with carboxyl groups (CNT-COOH) significantly improved its dispersibility in the PLA matrix. The mechanical properties, water barrier performance, and thermal stability of the PLA/sc-PLA/CNT films were also assessed. The incorporation of sc-PLA microspheres and CNT-COOH improved the tensile strength and modulus of the composite films with the optimal values achieved using 3 wt% CNT-COOH and 5 wt% sc-PLA microspheres. Using CNT-COOH as a filler significantly improved the thermal stability of the composite films compared to both the unmodified and CNT-modified films. The sc-PLA microspheres had a limited effect on increasing thermal stability, while particularly improved the water barrier properties of the PLA composite films. These improvements were attributed to the excellent dispersion of CNT-COOH in the PLA matrix and the crystallization-promoting effect of the sc-PLA microspheres on the PLA.