Investigation of Carbon Nanotube (CNT) Nanocomposites through Micro Scribing and Indentations

摘要

Polymeric carbon nanotube (CNT) nanocomposites have unique mechanical, electrical, and thermal properties. In this study, a micro indenter-scriber system was developed to perform scribing and indentation experiments on multi-walled carbon nanotube-polystyrene (MWCNT-PS) composites. MWCNT-PS samples with varying CNT concentrations were prepared through the micro injection molding process where injection enabled the partial alignment of CNTs in the flow direction through high shear stress. Scribing experiments were performed in the parallel and perpendicular directions to the CNT alignment. Cutting and thrust forces were measured and investigated the apparent friction coefficients with respect to the CNT concentrations. Small amount of CNT loading (i.e. 0.5 wt.%) on the polymer matrix reduced the apparent friction coefficient compared to the pure and higher concentration CNT composites. We also observed slightly higher forces when we scribed 5 wt.% CNT nanocomposites in the cross-flow direction compared to the in-flow direction. The hardness and modulus of elasticity were obtained from the micro indentation experiments. A mechanistic scribing force model was proposed based on the parameters obtained from the indentation tests and verified with the experimental scribing results.