Electrical and Mechanical Properties of Polymer Composite through the Use of Single-Walled Carbon Nanotube and Multi-Walled Carbon Nanotube

To manufacture composites with required properties, it is extremely important to select an appropriate filler. Carbon-based nano materials such as carbon black, graphene and carbon nanotube (CNT) have been extensively investigated as reinforcing and conducting fillers. Because of their high aspect ratio coupled with superior physical properties, 1-dimensional CNTs are ideal as filler materials to impart electrical conductivity to insulating polymers, while enhancing mechanical strength. In this study, we investigated the piezo-resistive and mechanical properties of composites consisting of two types of CNT classified as multi -walled CNT (MWNT) or single-walled CNT (SWNT) depending on the number of walls. Since MWNT and SWNT have different physical properties such as specific surface area and aspect ratio, this can affect the composite's performance. To more effectively evaluate the effect of MWNTs and SWNTs in composites, we used thermoplastic polyurethane (TPU) as a matrix, which is an insulating stretchable elastomer. Morphological and mechanical/electrical characterizations were conducted to determine differences in the MWNT and SWNT composites. In addition, we conducted dynamic strain sensing tests on each type of CNT composites to compare the sensitivity as a strain sensor. Differences in piezo-resistive behaviors were attributed to the loss of electrical contact points during stretching. These results can serve as a useful design guideline for the wider use of CNT composites.