An Inverse Numerical/Analytical Approach to Predict the Material Properties of Carbon Nanotube/Polymer Interphase

There is substantial interest in using carbon nanotubes (CNTs) to create multifunctional polymer composite materials with outstanding mechanical, electrical, and thermal properties. A difficulty in modeling the behavior of these systems is the non-bulk interphase region in these systems that forms due to nanoscale interactions between the embedded NTs and adjacent polymer chains. However, the mechanical properties of this interphase region are unknown and very difficult to measure directly from experimental testing due to the size scale of this interphase region. Thus a three-phase (nanotube, interphase and matrix) Mori-Tanaka micromechanical model has been developed such that the properties of this interphase region can be inferred from macroscale elastic data. Both as-received and functionalized NTs have been considered in order to investigate the influence of functionalization on predicted mechanical properties of the interphase. A hybrid finite element-micromechanical method is also used to consider the effect of NT waviness in modeling. Results show that the Young’s modulus of interphase region is significantly higher than that of bulk polymer and it must be considered as an independent reinforcement mechanism in CNT/polymer nanocomposites.