I want to know whether a polymer can be made as a thermally conductive material and for this how to choose the type of polymer (Thermoplastic, Thermosetting) and what technique to be adopted to increase its conductivity?
I think that graphite can be a good (better) candidate as well, as a close packing and high content (>20-30%w/w) of fillers is required if you want the thermal conductivity of your composites to be significantly increased.
Additionally if you don't want your composite to be electrically conductive you can try BN, Al2O3 µfillers, depending on the balance between efficiency and price you look for.
I agree with Viney and Jean and I would like to propose the usage of Thermosetting resines in order easily to improve the thermal stability of the composite.
The polymer matrix generally provides mechanical strength and/or chemical resistance that you need in your application. Also, processing is another important issue to be considered when comparing thermoset polymers with thermoplastics .
When you talk about thermal conductivity, you should keep in mind that to increase thermal conductivity, solid particles should form a 3d network in which solid particles are in direct contact to each other. That's why the percolation threshold for thermal conductivity occurs at higher solid contents compared with electrical and rheological percolation thresholds. If nano-particles do not form a 3d-network, they can even decrease the thermal conductivity due to scattering effects of the matrix/particle interface.
Thermal conductivity can be increased by the addition of conductive solid inclusions such as carbon nano-tube, graphite, Copper nano-wire ... Type of the solid inclusion (material and shape) can be determined from the desired extent of the increase in the conductivity,desired mechanical properties and percolation threshold (which affects final cost and processing). You also can use polymer blends as matrix and benefit from double and multiple percolation phenomena. It allows you to tune the thermal conductivity to a desired value.
Muthiah, thermal conductivity is directly proportional to electrical conductivity. You can not expect a thermal conductivity having anywhere near metals' thermal conductivity with polymer compounds / composites.
By the way (Ebrahim), "percolation threshold" is not in all cases the appropriate term (although most people are using it in general for any case). "Percolation" implies that the particles you are distributing in the polymer matrix are randomly distributed. This is only the case for particles which are bigger than 1 ... 2 µm. If smaller than that, the particles will not be randomly distributed but will form a very complex structure:
https://www.researchgate.net/publication/229816762_Electrical_conductivity_in_heterogeneous_polymer_systems._V_(1)_Further_experimental_evidence_for_a_phase_transition_at_the_critical_volume_concentration
This can be explained by non-equilibrium thermodynamics for which I delivered 2 key papers you can also find in my RG site.
Article Electrical conductivity in heterogeneous polymer systems. V ...
By using diphasic polymer systems you can also uncouple electrical from thermal conductivity by a selective dispersion of fillers, for more details have a look to our paper in Smart Materials & Structures: https://www.researchgate.net/publication/231025976_Conductive_polymer_composites_with_double_percolated_architecture_of_carbon_nanoparticles_and_ceramic_microparticles_for_high_heat_dissipation_and_sharp_PTC_switching?ev=prf_pub
Article Conductive polymer composites with double percolated archite...
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry
- Polymer Chemistry