Polymers in Defence and Aerospace Applications

Robin Young, Transport Relationship Manager from the Materials KTN attended the recent 2nd International Conference on Polymers in Defence and Aerospace Applications run by Smithers Rapra Technology Ltd in Hamburg.  This meeting  covered a dense and wide ranging technical programme with sessions including Novel Materials and Processes,   Electronic Materials and Applications,  Composites,  Carbon Nano Fibre -based materials,  Inorganic Nano-materials and Coatings.  With 54 attendees of which 19 were UK and 35 from overseas,  the conference had a strong industrial bias with only 10 delegates from Universities.

 Keynote papers were given by Dan Kells  (BAE Systems) on the UK's TEAM MAST consortium and the Strategic Focus of the UK Defence and Aerospace Knowledge Transfer Network. Case studies on coatings for solar radiation abatement,  self healing of fibre reinforced polymer composites,  and use of shape memory alloys  integrated into composites for improved damage tolerance and lightening strike protection were presented.   High performance applications of phosphazene elastomers now produced in 15 t/y quantities in Texas were described by Billy Goodwin from Materials Science Inc, pointing to the extreme low Tg (-70°C) and high thermal stabilities in these materials (up to 315ºC for short times).    Applications of centrifugal mixing of polyurethane foams were described by Karen Foster from AWE plc - revealing that the technique may offer some benefits compared to handmixing processes.   Novel processes and applications arising from inkjet printing of functional materials were described by Kay Yeong from Xennia Technology with defence related areas ranging from printing adhesives for composites joining, conformal circuitry,  flame resistant and camouflage coating,  low friction coatings, textured surfaces, flexible displays,  integrated electronics and optical engineering.   The need for fire resistant alternatives to FR4 substrates for multilayer printed circuit boards in aerospace electronics and the development of new "LuVo" high temperature thermoplastic substrates meeting V-0 classification was outlined by Thomas Apeldorn (TU Hamburg-Harburg).

A wide range of opportunities  for conductive polymers based on chimeric polymerisation of a novel difunctional monomer (NPEDMA)  was presented by Dhana Lakshmi (Cranfield University).  The thermo-oxidative stability of there materials and their low moisture uptake point to potential applications including molecular imprinted polymers (MIPs) for nanosensors (explosives sensor),  gas sensors,  lithographic patterning,  solar cells, supercapacitors and batteries and many more.

New applications and advantages of fluoropolymers were described by Stefano Mortara (Solvay Solexis, S.p.A). Coatings applications include those requiring corrosion resistance,  low surface tension while high discharge energy density leads to performance benefits for capacitors.  This material system also supports electroactive polymer variants which can be engineered to have intrinsic piezo, pyro and ferroelectric properties to address opportunities in sensors, actuators ultrasound imaging and non volatile printed memories.  Application in energy applications - notably fuel cells and portable photovoltaic systems were also described.

Selective laser sintering (SLS) of syntactic foams based on glass microballoons and nylon in a project running at AWE Aldermarston was described by Anna Walmsley.   Highly tailored syntactic foam structures from CAD files  having excellent specific properties for composites manufacturing were reported.

Design for Manufacture in an increasingly important theme.  In this meeting,  Chris Bailey from Greenwich University outlined the outputs from two UK projects which are based on advanced computational modelling to support design methodologies for packaging of electronic components (FLEXONLEAD and FAMOBS projects).   Developments in thermoplastic press forming of composites based on PEEK and PPS was described by Charlotte Vacogne from TWI and the theme of high Tg materials was continued in a paper on aromatic liquid crystal polymers (LCTs) by Theo Dingemans from Delf University of Technology.

Advances in analytical techniques based on microfocus X-ray diffraction at the European Synchrotron Radiation Facility in Grenoble were presented  by Richard Davies.   This technique probes the deep structure and micromechanics operating insitu in  performance composites undergoing separate or combined thermomechanical stresses.  Case studies included  fibre characterisation and imaging of woven composite microgeometry. thermal and stress induced lattice distortions and imaging of stress transfer in composite systems.

No materials conference is complete without a nanotechnology theme and in this meeting the theme  was covered by a cluster of five papers:  Use of low concentrations of carbon nanofibres in GFRP serving as tool for strain and damage sensing for structural health monitoring (University of Perugia), multifunctional composites with carbon nanotubes for space applications (Campinas State University),  while use of CNFs to improve Z conductivity in non woven carbon fibre veil structures to develop electromagnetic shielding capabilities was described by Andrew Austin (Technical Fibre Products).  

Studies of nanoclays and nanosilica additions to phenolic based glass composites for improved ablative rocket combustion chambers (Luigi Torre,  University of Perugia) revealed a clear advantage with silica processing.   Effects of nanoparticulate (attapulgite, carbon black) and  nickel powder additions to polyurethane based high performance shape-memory polymers and composites were described by Dr WM Huang, Nanyang Technical University with some unique thermo/moisture responsive features demonstrated.  Finally.  James Njugama (Cranfield University) presented on models for ageing and performance predictions of polymer nanocomposites for exterior aerospace and defence applications.

The conference closed with two papers on industrial coatings.  Geoff Armstrong (Indestructible Paint Ltd) described some current projects in which specialist coating systems have been developed to meet the complex performance, protection and decorative needs of composites used in the defence and aerospace industries.   Finally, and highly appropriate to a February meeting in ice-bound Hamburg,  Brian Burkitt (NuSil Technology LLC) described coating technologies which have been developed to reduce the adhesion of ice to aerospace or engineering structures based on silicone formulations which have been shown to offer much lower adhesion levels compared to Teflon coatings.