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materials | Thermally conductive


Figure 7: Thermal properties of PP-graphite


desalination plant heat exchanger tubes compared with metal types as manufactured and after 1,000h of fouling/scaling exposure


Source: T echnoform Kunststoffprofi le


developments at the fi rst Conducting Plastics conference held by Injection World publisher AMI last year. Among them were 3M and HPF, compound producers Ensinger, Lati and SABIC, and Technoform Kunststoffprofi le, which produces special types of tubing. Ensinger Account Manager Jürgen Fraer spoke about opportunities, challenges and applications for thermally conductive compounds. Depending on the system conditions (convection, heat transfer coeffi cient, power loss) the moderate thermally conductivity of thermally conductive compounds are suffi cient for their use as heat management materials, he noted. And while high fi ller loadings infl uence the characteristics profi le and the processing behaviour, not infrequently in a negative way, thermally he said conductive plastics can also be further modifi ed and functionalised to meet end-use requirements. Lati’s Special Compounds Marketing Manager Luca


Posca provided practical advice on materials selection, part design and moulding techniques when using thermally conductive plastics. He highlighted how, especially in parts with thin walls and compounds containing conductive fl akes, conductivity values vary considerably according to the axis they are measured along. “All parts requiring good transversal thermal conductivity may gain effi ciency introducing thicker


Conductive Plastics 2016


AMI will run its fi rst Conductive Plastics conference in North America later this year. Focused on the formulation and processing of both thermally conductive and electrically conductive plastics, the event will take place in Philadelphia, PA, USA, on 27-28 September. To fi nd out more about attending or exhibiting at the event, which is sponsored by Premix, contact senior conference coordinator Kelly Cressman. Tel: +1 610 478 0800; Email: kc@amiplastics-na.com. Or visit the conference website http://bit.ly/CPUS16


54 INJECTION WORLD | May 2016


walls where necessary,” he pointed out. Size and aspect ratio of particles infl uences thermal


conductivity. “Large fl akes featuring pronounced aspect ratios will provide much better conductivity even in low percentages.” Within the NanoMaster Project, Lati technicians have carried out many experiments. Dispersion and exfoliation of a graphene-like na- nographite was studied and the thermal conductivity of the resulting compound has been measured. “High aspect ratio enhances conductivity even at low fi ller content,” Posca said. “Preservation of particles integrity and aspect ratio is fundamental, so excessive shear stresses ought to be avoided as much as possible.” German processor Technoform Kunststoffprofi le is


developing applications for thermally conductive plastics in heat exchangers. In a discussion about seawater desalination plants, R&D Engineer Sebastian Ossadnik said the company had developed tubes made from polypropylene compounds containing graphite. He said the company had to develop special processing techniques to achieve optimum results. Even so, the “as extruded” thermal conductivity of its plastics tubes was lower than that for metal. However, further application testing showed thermal conductivity after ageing of the PP-graphite tubes to be better than some metallic alternatives due to the higher resistance to scaling.


Click on the links for more information:  www.lehvoss.dewww.3m.comwww.saint-gobain.comwww.hpfminerals.comwww.imerys.comwww.lanxess.comwww.grafe.comwww.ensinger-online.comwww.lati.comwww.tkp.biz (Technoform)


www.injectionworld.com


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