Preparation of highly thermally conducting polyamide 6/graphite composites via low‐temperature in situ expansion

Abstract

Highly thermally conducting polyamide 6 (PA6) composites with high loadings of low-temperature expandable graphite (LTEG) were prepared by an in situ exfoliation melting process, and the thermal conductivity of the composites was measured by a hot-disk method. A two-point method was applied to evaluate the electrical conductivity of the composites with various graphite loadings, and the thermal percolation was observed in the vicinity of the electrical percolation threshold concentration. Dynamic rheology analysis was used to define the geometric change caused by the interconnection of the in situ exfoliated graphite flakes. X-ray diffraction measurement confirmed that the exfoliation of LTEG was crucial to the overall thermal conductivity of the composites. Dynamic mechanical analysis revealed that the incorporation of LTEG significantly improved the damping properties of PA6. Thermogravimetric analysis and differential scanning calorimetry measurements were applied to study the thermal properties of the investigated PA6/LTEG composites.

Properties of microinjection‐molded polypropylene/graphite composites

“…Graphite, which is naturally abundant or can be synthesized from the petroleum coke or other precursor materials (i.e., synthetic graphite [SG]) , is known as a type of cost‐effective carbon filler to enhance the transport properties of polymer matrices thanks to its low density and high thermal and electrical conductivity as well as good dispersibility . Recently, it has been reported that the low‐temperature expandable graphite (LTEG) is an efficient additive that can significantly enhance the overall thermal and electrical conductivity of thermoplastic polymers at a relatively lower filler concentration when compared with flake graphite (FG) . For example, Luo et al found that the percolation concentration, p c , for LTEG filled high‐density polyethylene composites is about 20 wt%, which is half of that obtained from their FG‐containing counterparts.…”

Thermal, electrical and rheological behavior of high-density polyethylene/graphite composites

“…In our previous study [34], it has been confirmed that the in situ exfoliation of EG is beneficial to the construction of conductive pathways within the matrix. Moreover, the delaminated structure of EG was well observed during the fabrication process of HDPE/EG composite which was owing to the fact that the processing temperature (180 °C) was higher than the initial expanded temperature, i.e., 150 °C, for the EG used in this work.…”

Recent advances in graphene/polyamide 6 composites: a review

“…Researchers have been used GO 72,80,102 , FG 81,83,103 , RGO 83,104,105 and EG [106][107][108] to prepare PA6 composites by in situ polymerization. There are two routes of this method, one is anionic ring opening polymerization, and the other is hydrolytic polymerization.…”