عنوان مقاله [English]
Carbon nano tube (CNT) and coiled carbon nano tube (CCNT) have exceptional properties and can improve mechanical, electrical and thermal properties of nano composites. Among carbon nanostructure, a great deal of interests has been recently focused on CCNTs due to their specific properties which stem from the specific helical structure, which this field is one of the most interesting fields in engineering. In this paper, a multi-scale model is developed to study the mechanical properties in polyethylene reinforced by CNTs and CCNTs. Influence of volume fraction (VF) and geometric of the nano particle that is in two types of the CNT and CCNT, on overall stress - strain response have been investigated. Elastic modulus for each sample is calculated based on the linear part of stress-strain curve, and compared to each other. Results show with adding 1 percent of the CNT and CCNT to the polymer elastic modulus increases 17.5\% and 9.5\%, respectively, by using 1.5 percent of the CNT elastic modulus increase 21.4\%.
As a result, when the volume fraction increases the strength of nano composites enhances. In this paper also effect of orientation of CNT in matrix has been studied. Samples with 1 percent volume fraction in two isotropic and anisotropic states are generated and mechanical properties of these samples are studied. Results show a huge reduction in the stress-strain response of the anisotropic composite compared to the isotropic composite. Also effect of coil shape of CCNT were studied and compared with straight CNT. According to the results straight CNT is a better reinforcement compared to CCNT and as the coil angle increases, the overall stress-strain response improves as well.