Abstract
Melt-mixed composites based on polypropylene (PP) with various carbon-based fillers were investigated with regard to their thermal conductivity and electrical resistivity. The composites were filled with up to three fillers by selecting combinations of graphite nanoplatelets (GNP), carbon fibers (CF), carbon nanotubes (CNT), carbon black (CB), and graphite (G) at a constant filler content of 7.5 vol%. The thermal conductivity of PP (0.26 W/(m·K)) improved most using graphite nanoplatelets, whereas electrical resistivity was the lowest when using multiwalled CNT. Synergistic effects could be observed for different filler combinations. The PP composite, which contains a mixture of GNP, CNT, and highly structured CB, simultaneously had high thermal conductivity (0.5 W/(m·K)) and the lowest electrical volume resistivity (4 Ohm·cm).
Highlights
In order to achieve materials with high thermal conductivity, composites based on thermoplastics and thermally conductive fillers are an interesting alternative to metals
These results indicate that graphite nanoplatelets (GNP) is more responsible for increasing the thermal conductivity and that the electrical properties are mainly influenced by the carbon nanotubes (CNT)
Taking into account that PP/5 vol% G was non-conductive and a volume resistivity of 6.4·103 Ohm cm was measured for PP/2.5% carbon black (CB) XE2B, there is a synergistic effect with regard to the electrical properties
Summary
In order to achieve materials with high thermal conductivity, composites based on thermoplastics and thermally conductive fillers are an interesting alternative to metals. Mazov et al [33] reported synergistic effects for the thermal conductivity of melt-mixed polypropylene (PP) composites filled with CNT and CF, which were shaped by injection molding. In PE-based melt-mixed composites, Müller et al [1] found no enhancement of the thermal conductivity (⊥) for mixtures of MWCNT (NanocylTM NC7000) and expanded graphite (EG) (0.63 W/(m·K) @ PE/5 wt% MWCNT + 5 wt% EG) as compared to the use of the EG as a single filler (0.74 W/(m·K) @ 10 wt% EG). Composite materials based on polypropylene (PP) containing different kinds of carbon-based fillers were prepared using small-scale melt mixing compounding This investigation focused on PP, as it is a widely used material for bipolar plate applications [2,5,17,21] where both electrical and thermal conductivity play a role. The goal is to achieve a composite having simultaneously high thermal and high electrical conductivity at the selected loading
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
