CNT-volume-fraction-dependent aggregation and waviness considerations in viscoelasticity-induced damping characterization of percolated-CNT reinforced nanocomposites

Elastic and viscoelastic-damping behaviors of multi-walled carbon nanotube (MWCNT) reinforced polymer matrix nanocomposites are investigated by the HFGMC micromechanical method. Utilizing the elasticviscoelastic correspondence principle, the frequency dependent properties are derived analytically from the time dependent creep curve. The CNT displays transversely isotropic directional behavior, however, the polymer matrix and the interphase representing the CNT/polymer interactions, obey a viscoelastic constitutive law. The CNT percolation, random orientation and random arrangement within the matrix are considered. After validating the proposed micromechanical model by experimental results, the parametric studies, including the effects of the CNT aggregation, waviness and percolation states, the loading frequency, and the interphase features on the nanocomposite effective elastic modulus, creep compliance, storage modulus, loss modulus and hysteresis loop are conducted. It is found that considering the CNTVF-dependent aggregation state gives a threshold value of the CNTVF leading to improve the nanocomposite effective properties. Also, as the CNT wave amplitude increases, the effective properties are degenerated more. However, it includes a minor effect for the CNTVFs less than 0.3%. The CNT percolation threshold increases by increasing the aggregation level and the interphase thickness, too.