materials research | Graphene and nanofillers
based thermoplastic masterbatches for conventional and additive manufacturing processes. NanoMaster, explained Ben Hargreaves of Net
Composites, is running for four years to November 2015, with a budget of €6.4 million and 12 active partners. It aims to develop processes for large-scale and rapid production of graphene, expanded graphite and nano-graphite, as well as related machinery and processing methods and material systems. The project has already succeeded in producing new
The UK’s National Composites Centre hosted the graphene and nanofillers workshop and is currently expanding its development facilities
brought to bear in material selection, material and process understanding, dispersion methods and process optimisation, test methods and so forth. And NanoDiamonds, not surprisingly, do not come cheap. However, the potential is claimed to be vast. Carbodeon has recently tested in a polyamide 6,6
compound with 45% boron nitride filler. By replacing 0.1 wt. % of the filler loading with NanoDiamonds that were powder ball milled into it and extruded in one sequence, a 25% increase in overall thermal conductivity was achieved thanks to the chemical functionalisation achieved by the interface created between polymer and filler. McNally of Warwick has also worked extensively on the
challenges of formulating composites with carbon nanoparticles, particularly those of dispersing them in the melt using a continuous, cost-effective and scalable process, understanding the interfacial region between polymer and nanoparticle and creating defect-free, high purity nanoparticles. Whatever the process, there is a long list of parameters to consider and much work still to do. Much of this, McNally showed, involves basic
manufacturing issues for compounders, such as mixing time and temperatures, rotor and screw speeds, matrix melt viscosity, screw profile and configuration, feeding regime, filler loading and masterbatch dilution. Further systematic study is needed, he concluded, in the effects of varying process parameters and extruder design on nanoparticle dispersion and distribution and the effects of secondary processing of all kinds on carbon nanopar- ticle localisation. For those interested in getting into the market, there
have been and are quite a number of funded projects and industry consortia, because it is quite clear that no-one can go it alone with graphene. Among these is the NanoMaster, a European Framework Project 7 ‘Factories of the Future’ initiative to create graphene-
36 COMPOUNDING WORLD | February 2014
grades of expanded graphite and nano-graphite, which, along with other commercial grades, are used to produce graphene via a multi-stage chemical exfoliation process involving oxidative treatment, washing, filtration and reduction at up to 90% yield in less than 24 hours. Work is continuing to produce graphene of tailored flake diameter. Lab-scale compounding in the project has so far
focused on graphite-polypropylene compounds in order to determine the optimum scale-up conditions and provide materials for conventional processing. The partners are also preparing compounds via a solution blending process in order to investigate the effects of shear, carrying out simulation work to translate lab-scale compounding results to industrial-scale machinery. The next steps, in addition to producing graphene-
polymer compounds for use in conventional processing techniques, will include large scale production of graphite-polymer compounds, optimising the compres- sion moulding parameters, continued development of expanded graphite-ABS rods for use in the fused deposition modelling technique, the refinement of selective laser sintering for use with expanded graph- ite-PA 12 powders and producing these powders from pre-compounded materials. Among other initiatives, the EU’s Graphene Flagship
funding call closed on 5 February, but the Horizon 2020-funded Nanotechnologies, Advanced Materials, Biotechnology & Advanced Manufacturing & Processing (NMBP) call remains open until about March, with a much larger budget of €488 million this year and further calls to 2015. In addition, two UK-based but international Nano-Enhanced Materials Consortia are also open, led by Boskovic.
Click on the links for more information: ❙
www.nanoktn.com ❙
www.nccuk.com ❙
www.appliedgraphenematerials.com ❙
www.cnt-ltd.co.uk ❙
www.haydale.com ❙
www.carbodeon.com ❙
www.netcomposites.com
www.compoundingworld.com
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