Glass fiber hybrid composites molded by RTM using a dispersion of carbon nanotubes/clay in epoxy

Abstract

Nanocomposites based on epoxy and a mixture of clays and multi-walled carbon nanotubes (MWCNT) were produced by casting, and also molded by RTM using glass fibers as reinforcement, yielding a hybrid multi-scale micro/nanocomposite material. Two types of montmorillonite clays were used, natural (MMT-Na) and organophilic (MMT-30B). Higher viscosity was obtained for the mixture with MMT-30B and it was observed that this clay did not perform as well as the MMT-Na in helping the dispersion of the carbon nanotubes (CNT). The glass transition temperature (T g) of the nanocomposites increased in up to 6 °C with the addition of MWCNT and up to 10 °C with the addition of MMT-30B, differently from the MMT-Na which did not alter the T g of the material. By transmission electron microscopy, it was verified that more homogeneous dispersions and more intercalated structures were obtained with the MMT-30B than with the MMT-Na. Finally, the low clay content used and, especially, the very low MWCNT content, did not significantly alter the studied flexural properties.

Electrical conductivity behavior of epoxy matrix nanocomposites with simultaneous dispersion of carbon nanotubes and clays

“…The agglomeration of CNTs away from the MMT‐30B, caused by the intercalation/exfoliation process of this clay in this matrix, could explain the reduction in network formation and consequent decrease in conductivity (Figs. and ) and viscosity . On the other hand, after adding CNT and MMT‐Na + the viscosity of the system increased, supporting the argument of CNT assisted dispersion by MMT‐Na + clay verified by Liu and Grunlan .…”

“…On the other hand, after dispersing CNT and MMT‐30B in epoxy monomers, the viscosity was lower than the mixture of epoxy and MMT‐30B alone, suggesting the occurrence of agglomeration of nanoparticles . Adding CNT and MMT‐30B also decreased conductivity, which means that the possible network formation is less efficient, indicating that the volume occupied by intercalated/exfoliated MMT‐30B avoids the network formation by CNTs.…”

“…In this case, the conduction is caused by interfacial polarization in the conductive layer of the aggregates. As mentioned before, viscosimetry tests were performed for the mixtures of epoxy monomers, CNT and clays in our previous work . After sonicating CNT and MMT‐Na + with epoxy monomers, the viscosity of the system increased, supporting the argument of CNT assisted dispersion by MMT‐Na + clay verified by Liu and Grunlan .…”

“…d and f). These nanocomposites was also characterized by differential scanning calorimetry (DSC) and viscosimetry test, and reported in our previous study . From DSC analyses, it was observed an increase of 10°C on the glass transition temperature ( T g ) in samples with MMT‐30B and no changes on samples with MMT‐Na + .…”

Hybrid Nanocomposites With Organoclay and Carbon-Based Fillers for EMI Suppression

“…We ascribe this behavior again to the restrained polymer dynamics in the NC/resin interfaces. This dielectric phenomenon is not impeded by the presence of MWCNT in the samples, probably because the dispersion of the filler particles is not deteriorated by the coexistence of the clay and MWCNT [34], [35]. Concerning the electrical properties, we expect that the sufficiently high NC amount (ࣙ2 wt%) interrupts any created conductive network and weakens the electron tunneling effect, which is assumed in low MWCNT-loaded composites [36].…”