Influence of annealing on thermal and electrical properties of carbon nanotube yarns

The physical properties of dry-spun MWCNT yarns with diameters from 35 to 60 μm were systematically determined as a function of annealing up to 2700 °C. Raman spectroscopy showed a ∼5 fold increase in relative CNT crystallinity after annealing. Electrical conductivity and magnetoresistance (in fields up to 9 T) were measured from 2 K to 390 K. Thermal conductivity from 50 K to 300 K was determined using the parallel thermal conductance method. The electrical and thermal conductivities of the yarns both increased by over 100% after annealing to 2700 °C. The influence of adsorbed species on the electrical properties of the yarns was also studied.