materials feature | Thermal conductivity
amount of space in which they can fi t. So drives are getting smaller, and as a result of the higher specifi c power output of these drives, more heat needs to be dissipated, necessitating a new generation of thermally conductive, electrically insulating materials. The company has developed the Star-Therm W range for this niche. Epic Polymers has strong expertise in long-fi bre
Lehmann & Voss has developed a range of thermally conductive Luvocom compounds for heat dissipation
heavy trucks, and trailers. PolyOne says the move has helped Mars Otomotiv signifi cantly reduce total part cost, remove weight, and optimize its manufacturing and logistics. Mars Otomotiv reduced part weight by more than 30%. Daily production rates were increased by up to 50%, and secondary operations, which were needed for the aluminium parts, were eliminated, reducing cost by more than 20% per unit. Interestingly the original mould for the cast aluminium parts could be modifi ed to mould the polymer heat sinks.
“It is clear that metal replacement with engineered thermoplastics, which has been ongoing for years to help reduce weight or improve some aspect of performance, now is entering a new, more advanced phase with the need for plastics to answer more demanding require- ments, such as heat management.” So said Anne Hippert, marketing director, PolyOne Engineered Materials EMEAI in a talk on metal replacement with specialty thermo- plastic solutions in heat-sensitive applications at the SPE’s Antec conference in Dubai in January.
PolyOne is
working with LED lamp
manufacturers to replace
aluminium heat sinks with
thermoplastics
Hippert said that, in situations where conductivity is the main limiting factor, the high conductivity of aluminium sometimes may be over-engineered, and materials with thermal conductivities around 10W/m.K would allow the system to perform similarly. Materials with thermal conductivities over 1W/m.K would avoid heat build-up and would lower the temperature load in the system.
Electromechanical opportunities Another independent compounder, Epic Polymers, says that the growth in the use of electromechanical drive mechanisms is now being conditioned in the automotive industry in particular by the decreasing
20 COMPOUNDING WORLD | February 2014
reinforced compounds, and concentrates on materials with high mechanical properties as well as those with thermal conductivity. Its Star-Therm W compounds contain long glass fi bres as well as conductive fi llers (either boron nitride or, if electrical resistance is not critical, graphite—which has the advantage of being much cheaper than BN). The production process produces less shear than in processes for short-fi bre reinforced compounds, and so is gentler on the conductive additive. “The trick is to break up the agglomerations, but not too much,” says marketing and technology director Fred Panhuizen. Star-Therm W A-2, which contains BN, is for
thermally conductive gears and bearings. It has a thermal conductivity of 8 W/m.K and a mechanical performance comparable to a 30% glass reinforced PA 66. Epic says that, “on top of this, it has excellent wear and friction properties, even at elevated temperatures.” According to Panhuizen, the material represents a technological breakthrough. “It is the fi rst thermally conductive, electrically insulating material that displays good mechanical performance,” he claims.
The 8 W/m.K fi gure is an average of through-plane and in-plane conductivity; here, through-plane conductiv- ity is around 2 W/m.K. Panhuizen says Epic is well down the development path to produce a grade with through- plane conductivity of around 4 W/m.K, which should fi nd use in many new applications. Epic is working with numerous additives suppliers on the development. “It’s not just one magic additive that does it, it’s really the mix,” he says. “The formulations are quite complex.” Panhuizen set up Epic Polymers with a colleague after he left LNP, shortly before it was acquired by GE Plastics (now Sabic). LNP had earlier developed Konduit thermally
conductive compounds, and Sabic continues to offer Konduit grades. At K2013, Lanxess provided a similar message about electronic devices and assemblies getting smaller and more powerful as the reason for launching its Durethan TC thermally conductive polyamides. First out of the gate are two easy-fl ow PA 6 grades, Durethan BTC65 H3.0 EF and BTC75 H3.0 EF, containing 65% and 75% of a
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