MARCH 2006 BROADSHEET - Materials for Tomorrow
Our February seminar “Materials For Tomorrow” was organised by CETC Committee member, Roy Cuthbert.
Our first speaker, Richard Dunn, Managing Director of Goodfellow Cambridge Ltd, started with a ‘potted’ history of his company which was founded by Stanley Goodfellow in 1946 and the subject of a Management Buy-Out in 2004. Initially, they were suppliers of metals and high-tech materials to research labs, then in the 1960s became specialists in electro-metal deposition to form thin metal foils. During the 1980’s they added a range of polymers, ceramics and composites. Today some 80% of global sales are still in pure metals and alloys. Richard showed that some materials first used in the Stone Age, such as ceramics, remain in daily use today. He also predicted a ‘non-metal age’, where the currently very expensive processes of re-cycling will dominate the design of new items, followed by an ‘age of precision’, an engineers’ age where materials will be ‘fit for purpose’ and only one purpose!
Richard gave a number of interesting examples of where his products are used. The Genesis satellite used thin film to protect it when it orbited the sun, but, unfortunately, the helicopter failed to ‘catch’ it on its return so it was in a rather crumpled on the resulting photo. Cochlear implants use high purity aluminium. Beryllium is being used for the mirror segments to form the 6.6metre primary mirror of the James Webb space telescope to be launched in 2011, this being protected from the heating of the Sun by a shield the size of a tennis court!
Our second speaker, Paul Everitt, also from Goodfellow Cambridge Ltd., discussed polymers, their history, characteristics and uses.
Polymers are fairly modern materials dating from 1846 when natural rubber and gutta-percha were combined for electrical cable insulation; followed by Ebonite in 1851 and Celluloid in 1870. Methyl rubber came in 1900 and Bakelite and Polyesters in 1907. Then between WW1 and WW2 came Polystyrene, Polyethylene, Polypropylene and PVC.
The usage cycle of polymers has been relatively short, due to the development of ever more versatile derivations; PEEK being an amorphous version first synthesised by J Rose in 1975 and commercialised by ICI in 1981, with applications in aerospace, defence, electronics, nuclear, food processing etc. Some polymers are intrinsically conductive and find applications in electronic devices. By using selective laser sintering it is possible to make fairly complex shapes for medium to large volumes. Its ability to revert to its original shape after deformation by applying moderate heat increases its versatility, leading to applications in the medical arena. The latest applications concern light emitting polymers for ultra thin displays, and monitors where features such as eliminating backlights, colour filters and polarizer’s give LEP’s a big advantage over conventional methods. The flexible polymer battery which is being used in smart cards is another example of this remarkable material’s versatility.
Dr Deborah Pullen, from TWI Ltd, explained that plastic is a term that covers a range of materials formed by the polymerisation of repeat units or monomers, following the vulcanisation of rubber by Goodyear in 1839. The first synthetic plastic was seen at the Great Exhibition of 1862. Created by Alexander Parkes, it was called Parkesine. Cellulose Nitrate was developed at about the same time to replace the ivory used in billiard balls, however it had its drawback – such as being highly flammable! The last hundred years have seen considerable developments in the materials use; electronics, packaging, sports goods and lightweight structures for flight and space have all benefited. Today plastics have many very useful properties: lightweight, rigid or flexible, corrosion resistance, controllable diffusion properties, high automation of product manufacture, thermal control, easily pigmented and multi-functionality being some.
With packaging materials, the original need was for something to contain produce in order to carry it home! This has now evolved into a major element in the marketing process and more recently into a means of ‘conditioning’ the product at its point of use, such as the ‘widget’ in a can that allows CO² to fizz up the beer. Nowadays, it is possible for the packaging to detect things like the ripeness of fruit or the condition of vegetables. Lightness, protection from the environment, good gas permeation resistance, low cost, advertising potential, inertness and recyclability all make plastics an ideal packaging material. Deborah gave a number of examples of these features, as well as examples where plastics are re-cycled into other products.
In the medical world plastics are widely used to replace skin, tendons, cartilage and to connect body tissues. Keeping drugs and blood sterile, together with specialised coatings for implants, are further examples of the versatility of this material. Deborah talked about an increasing need to recycle to reduce waste and conserve fuel reserves. Currently over 30 tonnes of waste are produced for every 1 tonne of product! Perhaps the use of natural polymers like cellulose, collagen, keratin, gelatine, silk, rubber and wood will play a part?
All three presenters gave many more examples of these most interesting materials and it is clear that they will play an increasing role in a world where the need to re-cycle resources is essential. Their development has only just begun! Had today’s plastics been available how far could Ben Hogan have hit a golf ball and what might Jesse Owens’ time have been for the 100 yards given plastic running shoes?
With thanks to CETC member, Ray Roberts, of Webtec Products Ltd for this write-up
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