Mechanical behavior of carbon nanotube reinforced polymethylmethacrylate foam: A multi-scale finite element method approach

In the present study, considering the random distribution of carbon nanotubes in polymethylmethacrylate (PMMA) polymer, a multi-scale finite element method has been developed to investigate the mechanical behavior of these materials. In order to make realistic assumptions, the interface zone between the nanotubes and the matrix is simulated using the interfacial zone model (IZM), with its parameters obtained by calibrating the finite element model results with the results of experimental tests. Tensile tests and scanning electron microscopy (SEM) were used to study the mechanical properties and morphology of the PMMA foam samples reinforced with 0 wt%, 1 wt% and 2 wt% carbon nanotubes. Experimental results show that by adding 1 wt% and 2 wt% carbon nanotubes to PMMA foam, the tensile strength of the foam increases by 8% and 22%, respectively, compared to pure foam. Based on the results of the finite element models, the optimum percentage of the carbon nanotubes is 3.3 wt%, which gives the optimum modulus and tensile strength of 87 MPa and 4.02 GPa, respectively. The finite element model developed in the present study shows good agreement with the experimental results. Therefore, the impact of effective parameters on the mechanical properties of the foam can be easily studied based on the finite element method (FEM) results.