Tensile properties for paraffin wax and a nanocomposite produced with 2 wt.% Cloisite® 20A were measured within the temperature range of 10 to 30 °C. Young's modulus and maximum stress are significantly greater at 10 °C for the nanocomposite than those measured for the pure wax. Values for both materials decrease with increasing temperature and converge to where little difference exists as the wax enters a series of plastic crystalline states. Large enhancements in ductility for these nanocomposites reported previously are shown to be a consequence of a decrease in their brittle-ductile transition temperatures. Reduced crystallite size was observed via polarized optical microscopy for the nanocomposite and X-ray diffraction and transmission electron microscopy demonstrate preferred alignments of wax lamellae and organo-clay platelets under strain. Results indicate that a combination of proximity to mesophases and influence of organo-clay on wax morphology and on the fracture mechanism account for the observed high ductility under ambient conditions.
Bibliographical noteFunding Information:
This work is financially supported by the U.S. Department of Energy (Project DE-FC36-04GO14309). The authors would like to thank Mark Calhoun for help in preparing and tensile testing of composite samples.
- Brittle-ductile transition
- Paraffin wax
- Preferred orientation
- Toughening mechanism