thermally conductive | Technical feature
pipe applications because poorly dispersed carbon black is known to act as a mechanical weak point that may cause the pipe to burst at high pressure. As can be seen in Figure 5, the mechanical properties of the carbon black loaded compounds are better maintained when compared to graphite loaded materials. Unfortu- nately, the maximum thermal conductivity achievable for carbon black compounds is less than 1W/mK.
Conclusion
Figure 5: Mechanical properties at similar thermal conductivities for carbon black (E250) and graphite (KS44) loaded HDPE compounds Source: Imerys Graphite & Carbon
References: [1] R. Barry, Kunstoffe international 12/2013, p. 77-80
[2] Z. Han, A. Fina, Progress in Polymer Science (2011) vol 26, 7, p.914-944
[3] C. Raman, P. Meneghetti, “Boron nitride fi nds new applications in thermo- plastic compounds” Compounding World 5-6/2008, p.26-31
[4] D. McNally,
http://polymer-additives.specialchem.com/tech-library/article/ novel-ceramic-additive-packages-enable-lower-cost-thermally-conduc- tive-plastics
[5] A. Kayser “Raising thermal conductivity with hexagonal boron nitride” Compounding world 02/2012, p. 25-30
[6] R.H.C. Janssen, IR. K. Douven, H.K. van Dijk, “Thermally-conductive plastics: balancing material properties with applications needs”, Com- pounding World 2/2010, p.38-42
[7] D. Bonacchi “A Comparative Study of Timrex C-Therm001 and KS44 in HDPE” Eurofi llers 2013, Bratislava
[8] D. Bonacchi, R. Gilardi “Thermally conductive compounds for geothermal pipes” Compounding World 02/2012, p. 15-20
Thermally conductive plastics are gaining increasing attention. New markets and applications mean new specifi cations will be developed and understanding the potentials and pitfalls of new additives is of great importance. Of the carbon materials available for thermal conductivity improvement, graphite is the best performing. It is a good choice where high thermal conductivity is needed, although it has the drawback of decreasing mechanical properties. Carbon black can be used effectively in applications that require moderate increase of the thermal conductivity, such as geother- mal pipes, and has a lesser impact on the mechanical properties of the fi nal material.
About the author: Daniele Bonacchi is Development Scientist, R&D Polymer Applications at Imerys Graphite & Carbon in Switzerland. He holds a degree in Chemistry and a PhD in material science from the University of Florence. He is a specialist in carbon black behaviour in plastics and in the development of thermally and electrically conductive polymer compounds.
www.imerys-graphite-and-carbon.com
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