Mechanical property characterization of carbon nanotube modified polymeric nanocomposites by computer modeling

This paper reports a two-step modeling approach for predicting the effective mechanical properties of polymeric nanocomposites modified with single walled carbon nanotube (SWNT). In step one, the nano-heterostructures of the nanocomposites were represented by 3-D nanoscale cylindrical, square, or hexagonal prismatic representative volume elements (RVEs). Each RVE contained a long or a short carbon nanotube (CNT) and consisted of three phases, i.e., CNT, matrix, and interphase. The mechanical properties of each RVE were extracted from the modeling results of the RVE undergone three load tests, i.e., uniaxial tensile test, lateral expansion test, and axial torsional test, using appropriately derived formulae. The effects of the volume fraction of CNTs on the mechanical properties of the RVEs were studied. The equivalent mechanical properties of the nano-heterostructures were obtained by averaging the mechanical properties extracted from each RVE. In step two, micro/macroscale nanocomposites were represented by a 3-D microscale unit cell which was discretized into cubic elements. Using Monte Carlo method, each element was assigned the averaged mechanical properties of the RVEs with random CNT orientation and length type. The overall effective mechanical properties of the nanocomposites were predicted by a tensile test on the unit cell. The modeling results by this proposed approach was compared with and validated by the experimental data of the SWNT modified epoxy nanocomposites.