Effect of organoclay on mechanical and thermal properties of polycaprolactone/chitosan/montmorillonite nanocomposites

This study investigates the effects of sodium montmorillonite (Na MMT) and organoclay montmorillonite (ODA-MMT) on mechanical and thermal properties and surface morphology of polycaprolactone (PCL)/chitosan composites. The organoclay was prepared via ion exchange reaction, using octadecylamine (ODA) as an organic modifier. Nanocomposites of PCL/chitosan/ODA-MMT and microcomposite of PCL/chitosan/Na MMT were prepared by melt blending technique and were characterized. XRD and TEM results indicate the formation of intercalated-exfoliated nanostructure at low ODA-MMT contents. Tensile measurement shows an increase in tensile modulus, but a decrease in elongation at break for both micro and nanocomposites as the Na MMT and ODA-MMT contents are increased. Tensile strength is improved with the addition of up to 3 wt% of ODA-MMT but is decreased with further additions of the modified clay in the nanocomposites. However, it is reduced by the addition of Na MMT into the composite. Thermal stability in both nanocomposite and microcomposite is enhanced, particularly in the nanocomposites; the maximum thermal stability was observed at 3 wt% of ODA-MMT loading. The fractured surface morphology of the PCL/chitosan blend becomes more stretched and homogeneous in PCL/chitosan/ODA-MMT than in PCL/chitosan/Na MMT.