Preparation and characterization of tapioca starch-poly(lactic acid)-Cloisite NA⁺ nanocomposite foams

Tapioca starch, poly(lactic acid), and Cloisite NA+ nanocomposite foams, with four clay contents (1, 3, 5, 7, wt %), were prepared by melt-intercalation method. Selected structural, thermal, physical, and mechanical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy, differential scanning calorimetry, and an Instron universal testing machine, respectively. XRD results indicated that the 1 wt % nanocomposite foam did not show the characteristic basal reflection of the nanoclay. The 3, 5, and 7 wt % nanocomposite foams produced a mixture of intercalated and tactoid structures. The d001-spacing of 3, 5, 7 wt % nanocomposite foams produced increases of 11.40, 11.15, and 10.67 Å, respectively, compared to that of the pristine clay. The morphological study showed that the nanocomposite foams exhibited a noticeably reduced cell size, more compact cells, and increased cell density. Increasing clay content caused a decrease in melting temperature (Tm). Bulk spring index and bulk compressibility were influenced (P < 0.05) significantly with the addition of different amounts of clay.