Enhanced thermal conductivity of polyamide nanocomposites involving expanded graphite–carbon nanotube network structure using supercritical CO₂

Abstract

In this study, supercritical carbon dioxide (scCO₂) was used to form a network structure of expanded graphite (EG) and multi-walled carbon nanotube (MWCNT) to achieve high thermal conductivity. Continuous processes, such as supercritical drying and rapid expansion of supercritical solutions were applied to pristine graphite and MWCNT. Polyamide 6 (PA6) nanocomposites with scCO₂-treated EG and MWCNT were prepared by twin-screw extruder-based melt compounding. In the PA6 nanocomposites, the EG sheets were homogenously dispersed, while the MWCNTs were located between the EG sheets, thereby acting as a bridge for the EG. Subsequently, the 35 wt.% imbedding in PA6 nanocomposite had an effective heat transfer pathway and high thermal conductivity (2.12 W m⁻¹ K⁻¹). It was observed that supercritical fluid processing is a facile and effective strategy to improve the thermal conductivity of polymer nanocomposites.

Graphical Abstract

Keywords:

• thermal conductivity
• supercritical fluid
• expanded graphite
• carbon nanotube
• polymer nanocomposites

Disclosure statement

No potential conflict of interest was reported by the author(s)

Additional information

Funding

This work was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under Grant [number 20012926]; and the [Ministry of Science and ICT (MSIT, Korea)] under Grant [number 2021M3H4A3A01043764]; and the [National Research Foundation of Korea] under Grant [number 2020K1A3A7A09078089; Ministry of Trade, Industry and Energy; Ministry of Science and ICT, South Korea.