Two-Stage Simulation of Tensile Modulus of Carbon Nanotube (CNT)-Reinforced Nanocomposites After Percolation Onset Using
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https://doi.org/10.1007/s11837-020-04223-3 Ó 2020 The Minerals, Metals & Materials Society
NANOMECHANICS OF LOW-DIMENSIONAL MATERIALS
Two-Stage Simulation of Tensile Modulus of Carbon Nanotube (CNT)-Reinforced Nanocomposites After Percolation Onset Using the Ouali Approach YASSER ZARE
1
and KYONG YOP RHEE1,2
1.—Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 1 Seocheon, Giheung, Yongin, Gyeonggi 449-701, Republic of Korea. 2.—e-mail: [email protected]
We suggest a two-stage approach for simulation of the elastic tensile modulus of polymer–carbon nanotube (CNT) nanocomposites including CNT networks, considering the hardening and percolating characters of the interphase region. In the first stage of the calculation, the Ouali equation is used to estimate the modulus of hypothetical particles consisting of CNTs and the nearby interphase. In the second stage, the Ouali model is applied to determine the modulus of the nanocomposite using the polymer medium and simulated particles obtained from the first stage of the process. The predictions obtained using the model are tested against experimental results for various samples. Subsequently, the effects of each simulation factor on the nanocomposite modulus are discussed. The presented technique is verified by the good agreement between the experimental results and model calculations, together with the normal effects of the parameters on the nanocomposite modulus. The use of CNTs with radius (R) > 40 nm and an interphase with depth (t) < 10 nm results in a 180% improvement in the modulus of the nanocomposite, but the overall modulus is increased by 400% when using the minimum R value of 10 nm and the maximum t value of 25 nm.
INTRODUCTION Many researchers have focused on polymer–carbon nanotube (CNT) nanocomposites (PCNTs), due to the exceptional electrical, mechanical, magnetic, and thermal properties of CNTs in addition to their low weight, enormous surface area, flexibility, and chemical stability.1–15 The physical properties of PCNTs mostly depend on the dispersion of the CNTs in the polymer matrix. However, CNTs are commonly insoluble and typically aggregate in suspension due to the intrinsic van der Waals attraction between nanoparticles. Several techniques have been proposed to address this challenge, including modification of the CNT surface, sonication, or in situ polymerization in the presence of CNTs.16–18 With increasing addition of a conducting nanofiller into a polymer medium, a percolation onset is observed at which the electrical conductivity of the nanocomposite increases substantially and the insulating matrix becomes a conductive
nanocomposite.19,20 This behavior is associated with the formation of a conducting network in the polymer host at the onset of percolation. The percolation of CNTs in nanocomposites has been well explored in literature. Similarly, the mechanical properties of nanocomposites also exhibit percolation behavior.21–23 Favier et al.21 reported the extraordinary shear modulus of cellulose whis
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