Morphology, thermal and mechanical properties of nylon 12/organoclay nanocomposites prepared by melt compounding

Nylon 12 (PA12) nanocomposites with different organoclay loadings were successfully prepared by melt compounding. X-ray diffraction indicated the dominance of the exfoliated clay morphology throughout the matrix after mixing in a Brabender twin-screw extruder, in accordance with transmission electron microscopy observations. Thermogravimetric analysis showed that the thermal stability of the PA12 matrix was improved by about 20°C on incorporation of only 5 wt% clay. Tensile and nanoindentation tests indicated that the elastic modulus and the hardness steadily increased by about 52% and 67%, respectively, with a clay concentration up to 5 wt%, while improvements in tensile strength were limited. Impact strength decreased linearly by about 25% as the clay loading increased (up to 5 wt%), indicating an embrittlement due to clay addition, as evidenced by SEM observation on the fracture surfaces. The embrittling effect may be due to the weak interfacial adhesion between the clay platelets and the polymer matrix.