THERMALLY CONDUCTIVE | ADDITIVES


Demand for plastics with improved thermal conductivity is growing at double-digit rates.Peter Mapleston looks at some of the latest additive developments


Targeting a hot market


With the global market for thermally conductive plastics showing double-digit growth that is likely to be sustained well into the next decade, additive and compound technology suppliers are upping their game to secure their place. And there is plenty of potential: their products can be used in applications that range through the most obvious markets such as heat sinks for LEDs and luminaires and all sorts of electronics, through to heat ex- change systems and items with optimised haptics. Martijn Mies, Manager of R&D and Customer


Technical Service for Fire Retardant Additives and Specialty Products at Huber Martinswerk, dis- cussed the advantages of using Martoxid TM aluminium oxides as thermally conductive (TC) fillers at the Conductive Plastics 2018 conference organised by Compounding World publisher AMI in Pittsburgh in the US in March. He took a detailed look at Martoxid TM-4250, from Huber’s 4000-se- ries designed for polyamides, and compared performance against an aluminosilicate reference. Mies said some customers have expressed


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anxieties about abrasion in their processing equipment when using mineral-based TC additives. This is no surprise given that additive levels can be as high as 75%. At such levels, TM-4250 raises conductivity in a PA66 from around 0.25 W/m.K up to 2.5 W/m.K (in-plane). He said that despite the high loading, good elongation at break and impact strength is preserved. All TM-4000 products are described as soft calcined products with no sharp crystal edges. Tests carried out at Fraunhofer LBF in Darmstadt, Ger- many, on PA6 compounds measured material loss on platelets through a special slit die. They showed that TM-4250 is much less abrasive than many fillers that have lower Mohs hardness, such as aluminosili- cate (Table 1, page 21). Extrusion of the compound was also found to require around 30% less energy.


Targeting abrasion Dr Carsten Ihmels, who is Head of R&D/Technical Service in Adsorption & Catalysis at functional filler producer Nabaltec, says aluminium oxide is a


April 2018 | COMPOUNDING WORLD 19


Main image: Heat sinks are a key potential market for thermally conductive compounds


PHOTO: COVESTRO


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