International Journal of Composite Materials 2018, 8(1): 10-17 DOI: 10.5923/j.cmaterials.20180801.02 Dispersion of MWNT under Different Solvents and Its Effect on the Electrical Properties of Cured-Epoxidized Linseed Oil Composites E. Vigueras Santiago 1 , M. A. Camacho López 1 , J. E. Moreno Marcelino 2 , S. Hernández López 1,* 1 Laboratorio de Desarrollo y Caracterización de Materiales Avanzados (LIDMA); Facultad de Química de Química de la Universidad Autónoma del Estado de México (UAEM). Paseo Tollocan Esquina con Paseo Colón, s/n. Moderna de la Cruz, Toluca 2 Student in the Materials Science Master Program, UAEM Abstract Non-functionalized and functionalized multiwalled nanotubes (MWCNTs) were dispersed in epoxidized linseed oil (ELO) using an ultrasonic bath. Qualitative dispersion of the three different carbon nanotubes (CNTs) in four different solvents with and without ELO was followed by optical microscopy, and quantitative analysis of CNTs was performed by calculating the critical concentration from their percolation curves after they were thermally cured. Dimethyl formamide (DMF) was found to be a better solvent for dispersing the three kinds of MWCNTs, but some re-agglomeration of the functionalized MWCNTs occurs upon the addition of ELO. This effect had a weak impact, with the critical concentration of the polymer composites (PCs) being 18% higher for those prepared with functionalized MWCNTs than for those prepared with non-functionalized MWCNTs. Keywords Multiwalled carbon nanotubes, Electrical percolation, Nanoparticles dispersion, Epoxidized linseed oil 1. Introduction Multiwalled nanotubes (MWCNTs) are some of the most widely used nanoparticles for reinforcement in order to improve the mechanical [1, 2], thermal, tribological [1, 3, 4], optical and electrical properties of polymer matrices [5, 6]. In particular, recent work has showed that an appropriate dispersion of the particles is especially important for obtaining a low concentration threshold [5, 7]. However, obtaining a stable and homogeneous dispersion of MWCNTs into the polymer matrix is one of the main challenges in the production of MWCNT-based polymer composites. Good dispersion of CNTs in polymer matrices can be achieved by means of high power dispersion, compatibilizers, polymer-assisted melt blending [3, 8], and surfactants, resulting in the enhancement of the mechanical and thermal properties. [4, 8-10]. Physical and chemical functionalization of MWCNTs is also one of the most used strategies due to its relative simplicity and efficiency for improving the MWCNT dispersion through better interactions with the matrix polymer [1, 5, 9-14]. However, depending on the degree and nature of functionalization, they could degrade the electrical properties of MWCNTs as demonstrated by * Corresponding author: shernandezl@uaemex.mx (S. Hernández López) Published online at http://journal.sapub.org/cmaterials Copyright © 2018 Scientific & Academic Publishing. All Rights Reserved Park et al. [15], Lau et al. [10] and Moreno Marcelino [17]. Epoxy resin is a cross-linked polymer extensively used as the matrix for advanced composites [6, 11, 12] due to its good specific strength, stiffness, chemical resistance, and dimensional stability. Because of their high stiffness and strength, resistance to chemicals, good dielectric behavior, resistance to corrosion and microbial organisms, low shrinkage during curing and good thermal features, epoxy resins are the most important class of thermosetting resins with multiple engineering applications. Thus, several research efforts are currently being pursued for the development of the reinforcement of epoxy matrices with CNTs. Currently, vegetable oil-based polymers have attracted attention due to their feasibility for the production of polymers and composites that are environmentally friendly with a great variety of reinforcement particles [18-22]. Epoxidized linseed oil could be easily synthesized from linseed oil and hydroperoxy acid using several well-studied methods [23-27]. The obtained ELO could have an average of 6.0 oxirane rings per molecule and is a nonvolatile and non-polar liquid that could be thermally cured to make it a crosslinked, insoluble and non-processable resin. It could form stable films on several substrates, and it could be mixed with a great variety of fillers, including carbon nanoparticles. Most studies have focused on the evaluation of parameters such as type, size [28], functionalization, geometry, and purity of the MWCNT, with the studies of multiple properties, mainly mechanical,