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Heat Transfer

What Are Thermally Conductive Plastics?  Modified engineering and commodity thermoplastic resins with the ability to transfer heat.  Thermal conductivity is imparted by additives.


  • They are available in electrically insulative and electrically conductive grades.

  • They are up to 50% lighter than aluminum.

  • They are net shape moldable.

  • They provide greater design freedom and potentially lower cost than metals and ceramics.

In this demonstration, two molded parts are placed in contact with ice. 
On the left the conventional plastic part provides thermal insulation and therefore, when you touch the part it feels like the temperature of the air. 
On the right, the thermally conductive plastic reduces the temperature gradient between the ice and the top of the molded part to only 1 degree or less.  When you touch the part it actually feels like you are touching the ice itself.  It’s basically at the same temperature as the ice and condenses enough moisture from the air so it feels wet like the ice.



Conventional Plastic

 CoolPoly® Thermally

 Conductive Plastic

Material Thermal Conductivity

Foamed plastic
.02 W/mK
Conventional Plastic
.2 W/mK
2 W/mK
Thermally conductive plastic
1-20 W/mK
50 W/mK
200 W/mK
400 W/mK
1500 W/mK

To put thermal conductivity in perspective, here are the values measured in Watts per meter Kelvin (W/mK) for various materials. 

The thermal conductivity of materials spans about 5 orders of magnitude.  The electrical conductivity of materials, by comparison spans at least 22 orders of magnitude. 

At the most insulative end of the range is foamed plastics like Styrofoam®.  Many plastics are actually foamed to enhanced their insulation characteristics because stagnant or trapped air is a very good thermal insulator. 

Conventional plastics are about an order or magnitude more conductive than air but are still considered thermal insulators.  All plastics have a thermal conductivity near 0.2 W/mK regardless of their chemistry or typical additives. 

Glasses, like Pyrex®, have a thermal conductivity of about 2 W/mK, 10 times higher than plastics. 

CoolPoly® thermally conductive plastic grades range in thermal conductivity from about 1 W/mK to as high as 100 W/mK.  The majority of the grades are in the range 1 to 20 W/mK….making them 5 to 100 times the conductivity of conventional plastics.   For comparison purposes, both stainless steel (at 15 W/mK) and the ceramic aluminum oxide (at about 25 W/mK) have thermal conductivities in this same range.

Carbon steels have a thermal conductivity of about 50 W/mK.

Pure aluminum has a conductivity greater than 200 W/mK but extrusion and casting alloys range from about 50 to 150 W/mK.

Pure copper and silver have a thermal conductivity greater than 400 W/mK. 

Diamond has a thermal conductivity over 1000 W/mK and is an electrical insulator but is obviously rather expensive and difficult to process.

Infrared thermography of 3 x 3 inch injection molded plaques with 5 watts heaters attached to the underside of each.

T = 24ºC

T = 4ºC

Conventional Plastic

CoolPoly® Thermally Conductive Plastic

This is the best single example of the heat transfer difference between a  conventional and thermally conductive plastic. 
The infrared image shows color differences as a indication of temperature gradients in the part. 
Each part is a 3 x 3 x 1/8 inch (75 x 75 x  3 mm) injection molded plaque with a small 5 watt heater attached to the back side.

On the left, the conventional plastic can not spread or dissipate the energy and therefore, a “hot spot” develops in the center of the part. 

On the right, there are two important effects.  First, the input energy is spread throughout the part resulting in a more isothermal temperature distribution (noted by the similarity in color).  Secondly, since a much larger surface area has been heated, the energy is more efficiently transferred to the environment and the temperature of the device and “hot spot” is significantly reduced. 
If this were a real application the heater (or any heat generating device…a microprocessor, a resistor, a light bulb) would run significantly cooler.  Decreasing temperature almost always increases device efficiency, lifetime or power output. 
Specific plastics are often selected based solely on its ability to withstand a given hot spot temperature created in the application.  Reducing rather than surviving this temperature is one of the fundamental concepts of a thermally conductive plastic.  Continue to next >>

See Also

Thermally Conductive Plastics For Functional Heat Sinks Conformal elastomer heatsinks eliminates secondary interface requirements.  >>More

Thermally Conductive Plastics For Heat sinks & Thermal Management Solutions

In typical electronic power and air flow environments, CoolPoly thermally conductive plastics provide equivalent heat transfer to aluminum.  >>More

Thermally Conductive Plastics For Thermal Interface & Gaskets

molded from & over molded with CoolPoly Elastomers intimately conform to varying component heights and surfaces >>More

Thermally Conductive Plastics For Folded Fin Heatsinks

CoolPoly thermally conductive injection molding grade thermoplastics allow folded fin heat sinks designs with unique architectures and performance. >>More

CoolPoly® Material Solutions

A detailed look at CoolPoly solutions in specific applications.

Thermally Conductive Plastics For Enclosures

CoolPoly thermally conductive plastic enclosures have been commercially proven to reduce cost by as much as 50% compared to die cast aluminum housings while providing equivalent heat transfer. >> More

CoolPoly® Selection Tool

Not sure which material best suits your application?  Try our new CoolPoly selection tool.


Answers to the most commonly asked questions regarding thermally conductive polymers.

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