An investigation of buckypapers´ Young´s modulus utilizing nanoscale modeling and Molecular Dynamics simulation

The Young´s moduli of carbon nanotubes and carbon nanotube thin films (the so called buckypaper) are investigated using nanoscale mechanics and Molecular Dynamic (MD) simulation methods. The results show that the Young´s modulus of single walled (10, 10) carbon nanotubes ranges from 0.75 TPa to 0.9 TPa, which agrees well with some published data in the literature. For single layer buckypapers of single-walled tubes, the simulations gave a Young´s Modulus around 0.3 TPa. A Four-wall nanotube [(5, 5), (10, 10), (15, 15), (20, 20)] model was built to simulate Young´s modulus of multi-walled tubes and a little lower value was obtained than single walled, so does the multi-walled tube buckypaper. It was also found that the larger the separation distance between nanotubes in the buckypaper model, the smaller the value of Young´s modulus of the paper. The comparisons of the results between the MD simulations and the previously done experimental testings on bucky papers´ mechanical properties revealed some discrepancies for their Young´s moduli. The higher Young´s moduli values for buckypapers obtained in the MD simulations are deemed to be mainly due to the exclusion of such factors as particles impurity, uneven thickness, imperfect alignments, etc. From another point of view, these higher values may represent the optimal goal of Young´s moduli for buckypapers which could be achieved ultimately when their fabrication techniques are continuously improved in the future.