Chemical Engineering Seminar
There continues to be intense research effort in the field of polymer nanocomposites (PCN's) , but their potential has yet to be fully realised. Predominately, the practice has been to utilise solvent and/or sonication assisted mixing, in-situ polymerisation and template synthesis to prepare PCN's. All approaches have significant limitations and are not readily scalable. The preparation of PCN's using melt mixing, typically in twin-screw extruders, has also been reported. However, many studies utilised micro-extruders which operate with conical screws, the results from which are not scalable. Moreover, those studies that have employed industrially relevant parallel twin-screw extruders have not been systematic. The tendency has been for researchers to mix the NP of interest into the polymer melt using whatever extruder/mixer available with no appreciation of the parameters that control NP dispersion and distribution in polymer melts. Furthermore, many polymers are utilised in blends and localisation of NP's in either phase has not been widely reported. Effective NP dispersion is a non-trivial task in the production of PCN's. A further challenge is in understanding the interface between NP and polymer. The structure, morphology and properties of the interface govern many properties of composite materials. An appreciation of the factors required for scaling PCN preparation in a continuous process is essential. While many researchers try to achieve high levels of NP dispersion, in reality such composites will almost certainly go through some secondary process. This could include a second thermo-mechanical cycle in the case of injection moulding or solid-state or quasi-solid state uniaxial and biaxial deformation in the case of thermoforming or blow moulding. In this presentation, the processing parameters which govern effective mixing of NP's in polymer melts, and the effect of secondary processing and annealing on structural evolution and properties of PCN's will be discussed. Innovation in processing of these composites via the application of magnetic fields to align magnetic nanoparticles in polymer melts will be introduced.
. Polymer Carbon Nanotube Composites: Synthesis, Properties and Applications, (Eds. T. McNally and P. Pötschke), Woodhead Publishing Ltd. Cambridge, UK. ISBN 1 84569 761 8, ISBN-13: 978 1 84569 761 7, 2011.