Polymeric Materials Reinforced with Multiwall Carbon Nanotubes: A Constitutive Material Model (original) (raw)
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In this paper we have modified an existing material model introduced by Cantournet and co-workers to take into account softening and residual strain effects observed in polymeric materials reinforced with carbon nanotubes when subjected to loading and unloading cycles. In order to assess the accuracy of the modified material model, we have compared theoretical predictions with uniaxial extension experimental data obtained from reinforced polymeric material samples. It is shown that the proposed model follows experimental data well as its maximum errors attained are lower than 2.67%, 3.66%, 7.11% and 6.20% for brominated isobutylene and paramethylstyrene copolymer reinforced with multiwall carbon nanotubes (BIMSM-MWCNT), reinforced natural rubber (NR-MWCNT), polybutadiene-carbon black (PB-CB), and PC/ABS reinforced with single-wall carbon nanotubes (SWCNT), respectively.
The present study is concerned with a method for producing a reinforced polymer by introducing Carbon Nanotube into the polymeric host. It aims to investigate the tensile characteristics of Multiwall Carbon Nanotubes (MWCNTs) reinforced epoxy composites. Tensile test specimens of the composite were fabricated by increasing concentration of surface modified MWCNTs using molding method at room temperature. The investigation clearly exhibits the 1.25wt.% of epoxy/MWCNTs nanocomposites have enhanced tensile characteristics. These results suggest that targeted chemical modification of the carbon nanotube surface is an effective way to enhance the mechanical properties of carbon nanotube-polymer composites. The optimum loading of MWCNTs in polymeric host has been evaluated.
Multiwalled carbon nanotube reinforced polymer composites
Materials Science and Engineering: A, 2008
Due to their high stiffness and strength, as well as their electrical conductivity, carbon nanotubes are under intense investigation as fillers in polymer matrix composites. The nature of the carbon nanotube/polymer bonding and the curvature of the carbon nanotubes within the polymer have arisen as particular factors in the efficacy of the carbon nanotubes to actually provide any enhanced stiffness or strength to the composite. Here the effects of carbon nanotube curvature and interface interaction with the matrix on the composite stiffness are investigated using micromechanical analysis. In particular, the effects of poor bonding and thus poor shear lag load transfer to the carbon nanotubes are studied. In the case of poor bonding, carbon nanotubes waviness is shown to enhance the composite stiffness.
Materials & Design, 2016
In this investigation, nonlinear behavior of Multi Walled Carbon Nanotube reinforced epoxy resin is determined using experimental, numerical and micromechanical methods. Standard nanocomposite samples containing various weight fractions of MWCNTs were prepared and were tested. Experimental results show significant improvement in tensile and compressive mechanical properties of epoxy resin as a result of CNT addition. Compressive modulus of elasticity initially increased with nanotube content up to 0.45 wt. %. At higher CNT weight fractions, compressive modulus decreased slightly. Also, Field Emission Scanning Electron Microscope was used to obtain images of the samples' fracture surface. These images suggested a good CNT dispersion in the matrix. Numerical simulations are conducted to evaluate the nanocomposite elastic moduli using two different interface models. Numerical results suggest that the connector model predicts values lower than the thin shell interface model. Also, the elastic-plastic behavior of nanocomposites was estimated using a combination of micromechanical and numerical methods. To achieve this goal, micromechanical methods based on Mori-Tanaka and Halpin-Tsai models were used to predict the tensile stress-strain curves for the nanocomposites. Also, nanocomposite compressive behavior was predicted using a combination of numerical and micromechanical methods. Finally, the numerical and micromechanical results showed good agreement with experimental measurements.
Constitutive modeling of nanotube–reinforced polymer composites
Composites Science and Technology, 2003
In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalentcontinuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube shapes, sizes, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/LaRC-SI (with a PmPV interface) composite systems, one with aligned SWNTs and the other with three-dimensionally randomly oriented SWNTs. The Young's modulus and shear modulus have been calculated for the two systems for various nanotube lengths and volume fractions.
Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems
2001
In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalentcontinuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.
Evaluation of elastic properties of multi walled carbon nanotube reinforced composite
Computational Materials Science, 2014
Exceptional mechanical properties like high strength, stiffness and aspect ratio exhibited by carbon nanotubes, make them ideal reinforcements for nanocomposites. In this paper load transfer in multi-walled carbon nanotube (MWCNT) composites is studied under tension and compression loading conditions. Continuum mechanics model is used to evaluate the effective material properties using a representative volume element (RVE) approach. Numerical results are obtained using Finite Element Modeling (FEM) and these results have been validated with rule of mixture results. FEM results are found to be quite closer to the results obtained from rule of mixture. In the present work we have considered a range of matrix material, the range covers the matrix material from metal to polymer, i.e. taken in a form of the ratio of effective modulus of elasticity of CNT to that of matrix material E t /E m from 5 to 200. With the addition of the multi-walled CNT in a matrix at the volume fractions of 5.1%, the stiffness of the composite is increased by 46% for compressive loading and 14.9% for tensile loading, as compared with that of the matrix in the case of long CNT at E t /E m = 10. Multi-walled carbon nanocomposite are found to provide better value of young's modulus in compression as compared in tension, this is due to the higher inter-tube load transfer in compression. Comparative evaluation of material properties with single walled carbon nanocomposite is also done. It is established that multi-walled carbon nanotube composite provide a better resistance against compression as compared to single walled carbon nanotube composite. Effect of change in diameter and length of multi-walled carbon nanotube on stiffness of nanocomposite have also been investigated. Longer multiwalled carbon nanotubes are found to be more effective in reinforcing the composite as compared to shorter ones. FEM results are also found to be in close approximation with the experimental results, which validates the current model.
Structure and Mechanical Properties of Polymeric Composites with Carbon Nanotubes
Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference
Experimental investigations of single-wall carbon nanotubes (CNT) effect on the mechanical properties of polymeric composite materials based on epoxy matrix have been carried out. It has been found that addition of CNT at low concentration dramatically increases tensile strength (20 – 30 per cent growth) and Young’s modulus of the samples under study. Structure of polymeric composites with CNT was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM images of the samples under study confirm strong interaction between polymeric matrix and nano-additives, demonstrating intimate contact between CNT and epoxy surroundings which is of great importance for composite material reinforcement. Dependences of tensile strength and those of Young’s modulus on CNT concentration are discussed using micromechanics models for nanocomposites.