TECHNOLOGY | THERMALLY CONDUCTIVE
Right: Graphene is seen as a promising option for enhancing thermal
conductivity
is used to expand possible applications and various filler blends. Ready-to-use solutions are available and higher thermal conductivity products offering isotropic properties have been developed that are said to offer a good mechanical property/ price balance. The latest product introductions include
Silatherm 1466, which is based on alumosilicate. The company says that the 1466 grade is chemically similar to its standard Silatherm 1360 product but is much brighter in colour and offers better mechanical properties in compounds. A low grain size distribution of around an average 1.5 microns is offered. The Silatherm 1466-506 grade features a bi-modular grain size distribution. The Silatherm Plus 1443 range is based on aluminium oxide and is said to provide a special morphology and tri-modular grain size distribution. This grade is particularly recommended for thermoset applications requiring higher fill densities, where it can achieve thermal conductivities of between 4–6 W/mK. The company says that a new Silatherm range and a number of experimental grades will be released at the upcoming K2019 trade show in Germany in October, where it will also show some new application examples.
Below: An LED heat sink produced in a halogen free, flame retardant, thermally conductive PA6 compound from Witcom
Polyamide options Huber Martinswerk, part of the Huber Engineered Materials division of J M Huber, has developed its series of Martoxid alumina-based thermally conductive powders for modification of a range of polymers. It says that the Martoxid TM-4000 series products are specially designed for polyamides. The latest addition to the series is Martoxid TM-4250, which is said to increase orientation independent (isotropic) thermal conductivity in PA6 and PA66 to 2.5 W/mK (in-plane and through plane). Addition levels of up to 75 wt% are said to combine with low viscosity and good flowability,
allowing higher throughputs during extrusion at lower energy consumption. According to Huber, tests conducted at
Fraunhofer LBF in Germany on PA6 compounds confirm that the abrasion level of Martoxid TM- 4250 is low (the company says it is much less abrasive than fillers with a lower Mohs hardness such as aluminosilicate and glass fibre). The morphology and surface treatment of Martoxid TM-4250 is claimed to enable formulators to achieve good elongation at break and Charpy impact results. Huber says that the optimised rheological behaviour of the Martoxid TM-4000 series means they can be successfully employed in compounds for injection moulding of sub-millimetre wall thicknesses using standard moulding techniques. In addition, injection moulding production processes show a reduced cycle time of up to 50% compared to standard polyamide parts as a result of the faster cooling times possible from the higher thermal conductivity.
Developing applications While there are currently only a limited number of applications, thermal conductive plastic is an area seeing increased interest and more applications should develop in the near future, agrees Christine Van Bellingen, Business Development Manager at Witcom Engineering Plastics. “The demand is primarily driven by metal replacement for weight reduction and the need for heat dissipation in more confined spaces. However, there are probably still some technological and commercial barriers preventing quicker market development, and the thermally conductive additive producers still have some room for innovation,” she says. “The original demand for thermally conductive plastics for LED lamps has become a commodity market, where high levels - above 50 wt% - of the
20 COMPOUNDING WORLD | April 2019
www.compoundingworld.com
PHOTO: WITCOM ENGINEERING PLASTICS
PHOTO: SHUTTERSTOCK
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 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102
