Addition of reinforcement with very high thermal conductivity (ex. graphene) would enhance the thermal conductive value of the developed polymer composites. How would one cap the maximum weight percent addition addition of reinforcement to turn the polymer to be thermally conductive by mathematical equations?
Dear Vijay,
for the polymer composite be thermally conducting, the minimum volume fraction of the heat-conducting filler in the composite must be as high that the so-called percolation limit is achieved. The minimum volume fraction for percolation is about ca 36 % for spheric filler particles and might drop to slightly above 10 % for the short-fibre particles - it is shape-dependent. Of course, perfect mixing of components is assumed. The percolation means that the thin layers of the non-conducting polymer matrix are so thin that they practically do act as insulating zones. This concerns not only the heat conductivity but also electrical conductivity. You can for example look to the recent IUPAC document on polymers responsive to electromagnetic field that is available on my research-gate site.
Best regards, Jiri
Vijay Tambrallimath
A polymer isn't thermally conductive because of equations ( 'to turn the polymer to be thermally conductive by mathematical equations'). It's a fundamental property of the material.
Dear Vijay it is purely depends on type of filler. When adding more agglomeration is a main problem. Do surface treatment and then mix. So that you can mix maximum
Piyapong Buahom Yes, I agree. If there is no agglomeration and proper wettability is being observed with the reinforcement and matrix, would there be a way; mathematically to determine the maximum amount of reinforcement? Are there any mathematical models which can predict mechanical and thermal properties with addition of reinforcement? Alan F Rawle V R Arun Prakash
Dear Vijay,
for the polymer composite be thermally conducting, the minimum volume fraction of the heat-conducting filler in the composite must be as high that the so-called percolation limit is achieved. The minimum volume fraction for percolation is about ca 36 % for spheric filler particles and might drop to slightly above 10 % for the short-fibre particles - it is shape-dependent. Of course, perfect mixing of components is assumed. The percolation means that the thin layers of the non-conducting polymer matrix are so thin that they practically do act as insulating zones. This concerns not only the heat conductivity but also electrical conductivity. You can for example look to the recent IUPAC document on polymers responsive to electromagnetic field that is available on my research-gate site.
Best regards, Jiri
Dear Vijay Tambrallimath
Please develop your own calculation starting from Lewis-Nielson equation. It is very useful basic mathematical model to predict the thermal conductivity of the composite.
Best regard
Dear Vijay, thermal conductivity of a composite with thermally conductive filler depends on filler volume, particle size distribution and aspect ratio. A good overview may be found in papers of P. Bujard
Bujard P., Kühlein G., Ino S., Shiobara T., (1994) IEEE Trans. Compon. Packaging Manuf. Technol. A 17:527 DOI: 10.1109/ECTC.1994.367636
Ρ. Bujard, "Thermal Conductivity of Boron Nitride Filled Epoxy Resins.Temperature Dependence and Influence of Sample Preparation", Proceeding I-THERM 1988, pp. 41-49.
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Ρ. Bujard and J. P. Ansermet, "Thermally Conductive Aluminum Nitride Filled Epoxy Resin", Proceedings SEMI-THERM 1989, pp. 126-130.
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Ρ. Bujard, K. Munk and G. Kuehnlein, "Thermal Conductivity of a Chain of Particles in Close Contact in a Matrix of Epoxy Resin", 22 International Thermal Conductivity Conference, 1993-november-4-6.
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P. Bujard and A. Kuttler, "Relationship between the Thermal Conductivity and the Adiabatic Bulk Modulus of Epoxy Resins Loaded with Ceramic Particles" in Phonon Scattering in Condensed Matter, pp. 51-52.
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Best regards
Dear Alan F Rawle, really, composite isn't thermally conductive because of mathematical model, but equations allow us to find otimal content of conductive filler.
Jiri Vohlidal Piyapong Buahom Mohammed Hussein j. H. Al'Atia Juergen Finter Serge V. Shil’ko Thank you so much for your inputs. I would surely look into these suggestions.
You may also need to consider how the filler will be well mixed with the host matrix. Ideally, having more content of graphene would increase the overall thermal conductivity of the composite. But if they are not well mixed (wetted), there will be a gap at the interface, which can cause the thermal resistance and deteriorate the ideal thermal conductivity (and other properties) of the composite.
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