Thermal conductivity | materials feature
The heat is on: adding thermal conductivity to thermoplastics
Recent innovations in solutions for making thermoplas- tics thermally conductive are opening up new opportu- nities for compounders and their customers. There has been signifi cant action in the area around boron nitride (BN) in particular, with at least three suppliers reporting progress. BN (sometimes referred to as HBN, hexagonal boron nitride) is a synthetic mineral, made in a high temperature synthesis process directly from boron and nitrogen.
At the same time, numerous compounders are
working their own magic to conjure up new products based on BN (and other additives) with levels of thermal conductivity that were previously diffi cult or impossible to reach. Most of these products have low electrical conductivity too, but for applications where the combina- tion of thermal and electrical conductivity is actually an advantage, there are new offerings there as well. Thermally conductive thermoplastic compounds are
now a highly viable alternative to aluminium in such applications as heat-sinks in LED lighting. They can offer much greater design freedom and overall cost- effectiveness. These compounds offer key advantages in the design of thermal management components used in convection-limited environments. Applications are also arising in numerous non-lighting applications. Plastics are well known as poor heat conductors:
thermal conductivity in standard materials lies between 0.1 and 0.4 W/m.K. One BN supplier, ESK Ceramics, a
www.compoundingworld.com
3M company, says that using aluminium oxide as the fi ller, the maximum thermal conductivity that can be achieved is 2 W/m.K, and this is only at very high fi ller loadings. With the company’s 3M Boronid Cooling Fillers on the other hand, it is possible to reach an in-plane conductivity of up to 10 W/m.K with a loading of 50% in a polyamide compound, and still have good processing properties. A level as high as 15 W/m.K has even been achieved in a TPE compound. Boron nitride has a platelet structure, which means that its thermal conductivity is highly anisotropic. This anisotropy is also refl ected in mouldings, since the platelets tend to align in the direction of melt fl ow. Pure BN has an in-plane thermal conductivity of up to 400 W/m.K. ESK adds that the high aspect ratio of the platelets (approx. 1:30) enables thermal conduction paths to be generated even at low concentrations: it says that levels of over 5 W/m.K can be achieved at
Top: The use of thermally conductive
plastics in LED lights is
growing fast.
Mars Otomotiv is using
PolyOne’s
Therma-Tech in this example
There is growing interest in adding thermal conductivity to
thermoplastics. Peter Mapleston reports on the latest additives, compounds and applications
February 2014 | COMPOUNDING WORLD 13
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66
