event review | Compounding World Forum
More than 50 exhibitors put on displays at the Compound- ing World Forum
process technology that offers conductivity at lower loadings than previous Vulcan CBs, explained Angelos Kyrlidis, principal scientist for new business develop- ment at Cabot. Graphenes, which have a much higher aspect ratio
than carbon blacks, allow significantly lower loadings below 1%. The literature shows that graphene can also add thermal conductivity, barrier properties, and EMI shielding. Various methods are used to produce graphenes, and different processes have different capabilities. Cabot is currently exploring graphenes to see how they can be produced to give the promising results discussed in the literature. Using additives to enhance thermal conductivity of
plastics is just one aspect of managing heat in an application; the part design and operating environment are also crucial, said Jason Eckel, North American marketing director for specialty engineered materials at PolyOne. He explained that it is not essential for polymers to achieve equivalent thermal conductivity to aluminium, because in some designs and environ- ments, aluminium may be over-engineered. Instead, the overall design of a part should be considered and the heat management requirements understood. Compared to metals, plastics offer design freedom, and a new system design can deliver cost and efficiency benefits. In most heat-transfer applications, convection is the
limiting step, rather than conduction through the material, added Jörg Ulrich Zilles, head of R&D for HPF The Mineral Engineers / Quarzwerke. Neat polymers, with thermal conductivities of approximately 0.3 W/mK, need to be modified to reach a thermal conductivity of approximately 2 W/mK, above which convective transport will be the rate-limiting step, but it is not necessary to achieve the 200 W/mK of aluminium. Zilles compared an aluminium heatsink part with a polymeric part filled with Silatherm, HPF’s mineral additive for heat-conductive compounds, under various operating conditions. He also explained how Silatherm could be
20 COMPOUNDING WORLD | January 2015
used in conjunction with hexagonal boron nitride to give increases in thermal conductivity at a competitive cost and offer good retention of mechanical properties.
Optimization techniques Optimizing the formulation and processing of polymer compounds can be time consuming, but presenters offered ideas for improving the efficiency of the develop- ment process. Developing compounds with multiple, interacting
additives has traditionally been based on experience, but high-throughput screening offers a rapid method for optimizing polymer blends and compounds when that experience falls short, such as with new materials or when an additive must be changed because of new regulatory restrictions, said Gerhard Maier, CTO of service provider Polymaterials. The company uses design of experiments to determine what variables to test and then compounds and injection-moulds samples to measure using its rapid production technology. The technique does not replace conventional development, but makes it more efficient, said Maier. Computer simulation can be used to compare screw
configurations for compounding extruders, explained Philippe David, general manager of Sciences Comput- ers Consultants (SCC). While one-dimensional simula- tions give a snapshot of the process, three-dimensional simulations give a “video” and can be used to quantify mixing efficiency by tracking particles through the flow path. Simulation reduces scale-up time and speeds up product commercialisation by reducing the time needed for experiments. Although simulation is not a substitute for experience, it can supplement it by quickly providing data and increasing knowledge.
Compounding best practices Knowledge, communication and detailed planning are crucial for putting a compounding extrusion system together, explained Al Bailey, East Coast controls
www.compoundingworld.com
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