Preparation and characterization of tapioca starch–poly(lactic acid) nanocomposite foams by melt intercalation based on clay type

Tapioca starch (TS), poly(lactic acid) (PLA), and four different organoclays (Cloisite 10A, Cloisite 25A, Cloisite 93A and Cloisite 15A) were used to produce nanocomposite foams by melt-intercalation. Structural, thermal, physical and mechanical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and an Instron universal testing machine, respectively. The first XRD peaks for all four nanocomposite foams, were observed to shift to lower angles, indicating that intercalation occurred. The extent of intercalation depended on the type of organoclay and was exhibited in the sequence of Cloisite 10A > 25A > 93A > 15A. Glass transition temperatures (Tg), melting temperatures (Tm) and transition enthalpies (ΔH) of the foams were investigated by DSC. Radial expansion ratio (RER), unit density, bulk spring index (BSI), bulk compressibility, Young's modulus (E), water absorption index (WAI) and water solubility index (WSI) were influenced (p < 0.05) significantly with the addition of different organoclays into the TS/PLA matrix.