Optimizing the degree of carbon nanotube dispersion in a solvent for producing reinforced epoxy matrices

Asghar Habibnejad Korayem, Mohammad Reza Barati, Shujian Chen, George Philip Simon, Xiao Ling Zhao, Wenhui Duan

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The homogeneous incorporation of a small concentration of carbon nanotubes (CNTs) in epoxy matrices can enhance the mechanical properties of the composites. However, due to the high van der Waals interaction energy between CNTs, it is difficult to achieve a homogeneous dispersion of them in the epoxy matrix. Both processing conditions of the nanotubes, as well as the addition of surfactants have the potential to improve the dispersion. In this paper, the effects of sonication energy, CNT geometry and dispersant type on the dispersion degree of CNTs and consequent reinforcement of the epoxy matrix are investigated. Multi-walled CNTs with variable diameter and length were dispersed in ethanol using different sonication energies, with the aid of different dispersants. The results show that an increase in sonication energy initially leads to more CNT dispersion, although after a certain value of sonication energy, the level of dispersion remains constant. Moreover, excessive sonication energy was found to shorten the length of CNTs and thus decrease their aspect ratio. Due to the lower interaction energy of CNTs with larger (40–60 nm) diameter, compared to those with smaller diameter (10–20 nm), the larger diameter nanotubes showed a great ability to be dispersed, while CNT length showed no significant effect on the degree of dispersion. For greater CNT dispersion additives were incorporated. Copolymers which were able to disperse the CNTs primarily by steric repulsion were found to be more influential than those which dispersed the CNTs mainly by electrostatic repulsion, such as oleic acid. Furthermore, it was also found that copolymers yielding greater surface charge on the CNT were able to disperse CNTs more than those copolymers leading to a lower surface charge. It was found that, the incorporation of 0.1 wt.% pristine CNT using optimized influential parameters resulted in high levels of homogeneous dispersion in the epoxy matrix, with a modest improvement in mechanical properties of epoxy. This study provides further insight into the dispersion of CNTs in composite matrix and the degree to which a controlled dispersion can allow the CNTs to reach their potential as reinforcing nanofillers.
Original languageEnglish
Pages (from-to)541 - 550
Number of pages10
JournalPowder Technology
Volume284
DOIs
Publication statusPublished - Nov 2015

Keywords

  • Polymers
  • Composite materials
  • Mechanical testing
  • Electron microscopy

Cite this

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title = "Optimizing the degree of carbon nanotube dispersion in a solvent for producing reinforced epoxy matrices",
abstract = "The homogeneous incorporation of a small concentration of carbon nanotubes (CNTs) in epoxy matrices can enhance the mechanical properties of the composites. However, due to the high van der Waals interaction energy between CNTs, it is difficult to achieve a homogeneous dispersion of them in the epoxy matrix. Both processing conditions of the nanotubes, as well as the addition of surfactants have the potential to improve the dispersion. In this paper, the effects of sonication energy, CNT geometry and dispersant type on the dispersion degree of CNTs and consequent reinforcement of the epoxy matrix are investigated. Multi-walled CNTs with variable diameter and length were dispersed in ethanol using different sonication energies, with the aid of different dispersants. The results show that an increase in sonication energy initially leads to more CNT dispersion, although after a certain value of sonication energy, the level of dispersion remains constant. Moreover, excessive sonication energy was found to shorten the length of CNTs and thus decrease their aspect ratio. Due to the lower interaction energy of CNTs with larger (40–60 nm) diameter, compared to those with smaller diameter (10–20 nm), the larger diameter nanotubes showed a great ability to be dispersed, while CNT length showed no significant effect on the degree of dispersion. For greater CNT dispersion additives were incorporated. Copolymers which were able to disperse the CNTs primarily by steric repulsion were found to be more influential than those which dispersed the CNTs mainly by electrostatic repulsion, such as oleic acid. Furthermore, it was also found that copolymers yielding greater surface charge on the CNT were able to disperse CNTs more than those copolymers leading to a lower surface charge. It was found that, the incorporation of 0.1 wt.{\%} pristine CNT using optimized influential parameters resulted in high levels of homogeneous dispersion in the epoxy matrix, with a modest improvement in mechanical properties of epoxy. This study provides further insight into the dispersion of CNTs in composite matrix and the degree to which a controlled dispersion can allow the CNTs to reach their potential as reinforcing nanofillers.",
keywords = "Polymers, Composite materials, Mechanical testing, Electron microscopy",
author = "{Habibnejad Korayem}, Asghar and Barati, {Mohammad Reza} and Shujian Chen and Simon, {George Philip} and Zhao, {Xiao Ling} and Wenhui Duan",
year = "2015",
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language = "English",
volume = "284",
pages = "541 -- 550",
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Optimizing the degree of carbon nanotube dispersion in a solvent for producing reinforced epoxy matrices. / Habibnejad Korayem, Asghar; Barati, Mohammad Reza; Chen, Shujian; Simon, George Philip; Zhao, Xiao Ling; Duan, Wenhui.

In: Powder Technology, Vol. 284, 11.2015, p. 541 - 550.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Optimizing the degree of carbon nanotube dispersion in a solvent for producing reinforced epoxy matrices

AU - Habibnejad Korayem, Asghar

AU - Barati, Mohammad Reza

AU - Chen, Shujian

AU - Simon, George Philip

AU - Zhao, Xiao Ling

AU - Duan, Wenhui

PY - 2015/11

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N2 - The homogeneous incorporation of a small concentration of carbon nanotubes (CNTs) in epoxy matrices can enhance the mechanical properties of the composites. However, due to the high van der Waals interaction energy between CNTs, it is difficult to achieve a homogeneous dispersion of them in the epoxy matrix. Both processing conditions of the nanotubes, as well as the addition of surfactants have the potential to improve the dispersion. In this paper, the effects of sonication energy, CNT geometry and dispersant type on the dispersion degree of CNTs and consequent reinforcement of the epoxy matrix are investigated. Multi-walled CNTs with variable diameter and length were dispersed in ethanol using different sonication energies, with the aid of different dispersants. The results show that an increase in sonication energy initially leads to more CNT dispersion, although after a certain value of sonication energy, the level of dispersion remains constant. Moreover, excessive sonication energy was found to shorten the length of CNTs and thus decrease their aspect ratio. Due to the lower interaction energy of CNTs with larger (40–60 nm) diameter, compared to those with smaller diameter (10–20 nm), the larger diameter nanotubes showed a great ability to be dispersed, while CNT length showed no significant effect on the degree of dispersion. For greater CNT dispersion additives were incorporated. Copolymers which were able to disperse the CNTs primarily by steric repulsion were found to be more influential than those which dispersed the CNTs mainly by electrostatic repulsion, such as oleic acid. Furthermore, it was also found that copolymers yielding greater surface charge on the CNT were able to disperse CNTs more than those copolymers leading to a lower surface charge. It was found that, the incorporation of 0.1 wt.% pristine CNT using optimized influential parameters resulted in high levels of homogeneous dispersion in the epoxy matrix, with a modest improvement in mechanical properties of epoxy. This study provides further insight into the dispersion of CNTs in composite matrix and the degree to which a controlled dispersion can allow the CNTs to reach their potential as reinforcing nanofillers.

AB - The homogeneous incorporation of a small concentration of carbon nanotubes (CNTs) in epoxy matrices can enhance the mechanical properties of the composites. However, due to the high van der Waals interaction energy between CNTs, it is difficult to achieve a homogeneous dispersion of them in the epoxy matrix. Both processing conditions of the nanotubes, as well as the addition of surfactants have the potential to improve the dispersion. In this paper, the effects of sonication energy, CNT geometry and dispersant type on the dispersion degree of CNTs and consequent reinforcement of the epoxy matrix are investigated. Multi-walled CNTs with variable diameter and length were dispersed in ethanol using different sonication energies, with the aid of different dispersants. The results show that an increase in sonication energy initially leads to more CNT dispersion, although after a certain value of sonication energy, the level of dispersion remains constant. Moreover, excessive sonication energy was found to shorten the length of CNTs and thus decrease their aspect ratio. Due to the lower interaction energy of CNTs with larger (40–60 nm) diameter, compared to those with smaller diameter (10–20 nm), the larger diameter nanotubes showed a great ability to be dispersed, while CNT length showed no significant effect on the degree of dispersion. For greater CNT dispersion additives were incorporated. Copolymers which were able to disperse the CNTs primarily by steric repulsion were found to be more influential than those which dispersed the CNTs mainly by electrostatic repulsion, such as oleic acid. Furthermore, it was also found that copolymers yielding greater surface charge on the CNT were able to disperse CNTs more than those copolymers leading to a lower surface charge. It was found that, the incorporation of 0.1 wt.% pristine CNT using optimized influential parameters resulted in high levels of homogeneous dispersion in the epoxy matrix, with a modest improvement in mechanical properties of epoxy. This study provides further insight into the dispersion of CNTs in composite matrix and the degree to which a controlled dispersion can allow the CNTs to reach their potential as reinforcing nanofillers.

KW - Polymers

KW - Composite materials

KW - Mechanical testing

KW - Electron microscopy

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