Extruded Starch-Nanoclay nanocomposites: Effects of glycerol and nanoclay concentration

Wheat starch-Cloisite Na+ nanoclay composites containing different glycerol and nanoclay concentrations were extruded using a twin-screw extruder. X-ray diffraction and transmission electron microscopy were used to determine the extent of nanoclay dispersion and thermogravimetric analysis was used to characterize thermal stability of composites. Also, water absorbance was measured for each sample. The extent of nanoclay dispersion in samples containing 47 wt% total plasticizer concentration depended on glycerol concentration. For these samples, adding 5 wt% glycerol produced mostly exfoliated nanoclay, whereas adding 10 or 15 wt% glycerol produced intercalated nanoclay. Also, nanoclay composites exhibited improved thermal stability and reduced water uptake compared to samples with no nanoclay. However, thermal stability and water absorbance were not affected by the extent of nanoclay dispersion.