Nonlinear Multi-Scale Finite Element Method to Predict Tensile Behavior of Carbon Nanotube-Reinforced Polymer Composites

Authors: Ehsan Mohammadpour, Mokhtar Awang

Abstract: The ability of carbon nanotubes (CNTs) to consider as the strongest and stiffest elements in nanoscale composites remains a powerful motivation for the research in this area. This paper describes a finite element (FE) approach for prediction of the mechanical behavior of polypropylene (PP) matrix reinforced with single walled carbon nanotubes (SWCNTs). A representative volume element is proposed for modeling the tensile behavior of aligned CNTs/PP composites. The CNT is modeled with solid elements. Modified Morse potential is used for simulating the mechanical properties of an isolated carbon nanotube. The matrix is modeled as a continuum medium by utilizing an appropriate nonlinear material model. A cohesive zone model is assumed between the nanotube and the matrix with perfect bonding until the interfacial shear stress exceeds the bonding strength. Using the representative volume element, a unidirectional CNT/PP composite was modeled and the results were compared with corresponding rule-of-mixtures predictions. The effect of interfacial shear strength on the tensile behavior of the nanocomposite was also studied. The influence of the SWCNT within the polymer is clearly illustrated and discussed. The results showed that polymer's Young's modulus and tensile strength increase significantly in the presence of carbon nanotubes.

Direct link: http://www.scientific.net/JNanoR.26.169

Optimum Dispersion Technique of Carbon Nanotubes in Epoxy Resin as a Function of the Desired Behaviour

Authors: S.G. Prolongo, A. Jiménez-Suárez, B.G. Melitón, M. Campo, A. Ureña

Abstract: The use of carbon nanostructures for epoxy matrices modification has been widely studied, nevertheless there are several alternative methods for manufacturing that try to avoid difficulties related to their tendency to keep entangled. The use of the calendering approach and high shear mixing alternatives is common for dispersing these nanoreinforcements. The present article compares these two methods as well as possible synergies from the use of the two alternatives together. It has been found that the dispersion technique used modifies the final dispersion level reached as well as on the final properties of the different nanocomposites. Nevertheless, this effect depends on the type of nanoreinforcement (structure and functionalization) and the property measured. Results suggest that each carbon nanostructure requires an individual design of the dispersion stage to get the optimum properties. Thus, the optimum technique may be different depending on the final desired properties, and the dispersion cycle should be designed carefully depending of the final material aim and the nanostructure used. Nevertheless, typical dispersion cycles are currently applied for different type of nanoreinforcements.

Direct link: http://www.scientific.net/JNanoR.26.177