Thermally expanded graphite polyetherimide composite with superior electrical and thermal conductivity

TL;DR

This study presents a simple solution mixing method to create expanded graphite/polyetherimide composites with significantly enhanced electrical and thermal conductivities, suitable for thermoelectronic applications.

Contribution

The paper introduces a cost-effective fabrication technique for EG/PEID composites that preserves the graphite structure, achieving high conductivity improvements.

Findings

Electrical conductivity increased to 969 S/m with 10wt% EG filler.

Thermal conductivity enhanced by 3070% to 7.3 W/mK.

Theoretical model highlights interfacial effects on conductivity.

Abstract

Thermally expanded graphite (EG) polymer composite has high potential in modern thermoelectronic industry due to cost effectiveness, excellent electrical and thermal properties. In this study, we report that expanded graphite polyetherimide(EG/PEID) composite has been fabricated by simple solution mixing technique, reinforcing a low cost EG filler into host polymer matrix, polyetherimide (PEID). This technique enables the inclusion of 3D graphitic filler into polymer matrix retaining the worm structure of expanded graphite, thus developing continuous network throughout the composite. In result, ~19 orders of magnitude rise of the polymers electrical conductivity up to 969 S/m has been achieved upon the inclusion of the 10wt% of EG filler. Theoretical prediction using effective medium approach reveals the impact of an imperfectly conducting interface and interfacial tunneling on electrical conductivity of the composites. We also report that 10wt% EG filler composition composite exhibits the thermal conductivity (k) value of 7.3W/mK, implying significant enhancement of 3070% compared to pure PEID. Scanning Electron Microscopy (SEM) represents the morphology of fillers and composites, revealing the preserved structure of EG to develop the conductive pathway between polymer and filler. Investigation on the structural properties before and after the thermal expansion of EG fillers has been performed using Raman, X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) analysis. In summary, a simple fabrication route of solution mixing has been demonstrated to achieve an outstanding electrically and thermally conductive EG/PEID composite without compromising the efficiency of EG filler structure. The expanded graphite-based polymer composites can retain their outstanding properties in wide range of thermal and electronic industry.