Analysis of the roles of interphase, waviness and agglomeration of CNT in the electrical conductivity and tensile modulus of polymer/CNT nanocomposites by theoretical approaches

This study focuses on the roles of interphase between polymer matrix and CNT, waviness and agglomeration of CNT on the electrical conductivity and tensile modulus of polymer/CNT nanocomposites (PCNT). Several simple equations for percolation threshold, effective volume fraction of CNT and the fraction of networked CNT above percolation threshold are expressed assuming the roles of the mentioned parameters. After that, two proper models are applied to express the conductivity and modulus of PCNT by the influences of interphase, waviness and agglomeration. Both conductivity and modulus show similar correlations with these parameters. It is shown that interphase thickness (t), electrical conduction of CNT (σ_N) and modulus of CNT network (E_N) largely affect the electrical conductivity and tensile modulus of PCNT. The best relative conductivity (ratio of PCNT conductivity to polymer conduction) as 14*10¹⁷ is achieved by the highest levels of t = 20 nm and σ_N = 2.5*10⁵ S/m, while t < 6 nm produces the relative conductivity of 0.3*10¹⁷. Furthermore, the tensile modulus of PCNT improves by 2100% at t = 20 nm and E_N = 1900 GPa, whereas about 110% improvement of modulus is shown by t < 6 nm at different “E_N”.