The demise of Carilon – Shell’s polyketone material that took 10 years to develop and five years to die – spells the end of an innovative plastic, but not the end of innovation using plastics.

Despite its novel structure and striking properties, Carilon never grew beyond a handful of niche applications. It was the first truly new polymer in a long time. Many other promising plastics are coming out of research laboratories – from composites to biodegradables – but real innovation will stem from the intelligent and creative use of traditional materials.

Every plastics manufacturer worth its salt constantly adds new grades to its portfolio, making them easier to process, more temperature resistant and so on. But very few genuinely new plastics are being introduced – forcing designers and plastics processors to devise new and ingenious ways of maximising performance.

Think of 1938 and you think of the eve of WW2: Spitfire bombers, steam trains – and Teflon. The self-proclaimed ‘slipperiest substance in the world’ was originally developed by DuPont at this time and used in the US in the same way that it is today: as a coating for frying pans. But it has also found use in industries ranging from automotive to fabrics. This is particularly true in the recent past. It has even made it into space.

British company Holscot Industrial, based in Grantham, is an unlikely developer of rocket science. But in its own way, the plastics manufacturer has contributed to space travel. Holscot uses a range of traditional techniques – such as welding, vacuum forming, extrusion and heat shrinking – to process fluoropolymers such as Teflon. Its Teflon FEP (fluorinated ethylene propylene) rocket fuel tank claims to be a first – in that it is a cheaper way of handling liquid fuel. "We’re taking advantage of the material’s high chemical resistance," says managing director David Joyce. Tanks for liquid fuel are usually machined from titanium, so the plastic alternative is both lighter and cheaper to produce.

A 25 micron layer of Teflon has led to longer lasting shock absorbers that have closer engineering tolerances

Even the most traditional use of Teflon – as a non-stick coating – is being adapted for other industries. Barcelona-based Coatresa has devised a technique for applying very thin Teflon coatings to industrial components.Jordi Pujol, the company’s technical director, says: "We have coated the hydraulic cylinders used in automotive shock absorbers with a 25 micron layer of Teflon." Usually, he says, a 1mm-thick lubricating sleeve is placed on the shock absorber piston. If it ruptures, oil will seep into the gap between piston and cylinder and the unit will fail and need to be replaced. The Teflon coating is more robust and allows closer engineering tolerances, because it makes only a very slight difference to the size of the final part.

"Many engineers are not aware that Teflon can be used as a coating," says Pujol. "They think that it can only be used to mould solid components." The technique is already used to coat more than 30,000 components every day, which are supplied to the PSA Group (which manufactures Peugeot, Citroen and Talbot cars). Pujol admits that the technology is not very different to that used for coating frying pans. But he is developing a new technique that works at temperatures far below the traditional 400[degrees]C.

Coatresa and Holscot are just two of the winners in DuPont’s Plunkett Awards, which recognise innovative uses of Teflon.

Rubber – where?

A deceptively mature set of materials – thermoplastic elastomers, or TPEs – have also wormed their way into the market through constant development and new processing techniques. TPEs are 'rubbery' plastics that are displacing natural rubber in many applications because they are easier to process and recycle. AES, for example, has developed grades of TPE (thermoplastic elastomer) that can be laminated to other plastics. Ordinarily, it is difficult to make a TPE adhere to polar plastics such as polyester or nylon. But this new development – with the help of an additive called TB/TPV – will allow TPEs to be used in a wider range of products.

"Traditionally, polyolefins will not bond to polar substances," says Jay Griffith, business director, industrial markets. "We're looking to combine TB/TPV with all our products to develop new applications." TB/TPV takes the form of a film, which is extruded directly onto a woven fabric (such as polyester). The TPE can then be extruded onto the TB/TPV layer. To date, AES has used the technology to make ducting hose and sheet applications. But the promise of sticking a TPE layer to other plastics has greater potential.

"We could bond TPE to etched Teflon, which is good for applications such as pump diaphragms," says Griffith.

The technology will also help AES in its attempts to grow its presence in the consumer market: applications such as 'soft feel' toothbrushes and ergonomic padding on power drills are a potentially lucrative market for AES. "Different grades of TPE stick to different plastics," says Griffith. "Now, we can do nylon, peroxide and EPDM. Soon, we will add ABS, polystyrene, polycarbonate and PC/ABS."

DuPont Dow Elastomers, another major player in the field, has introduced an online elastomer evaluation tool that allows users to assess resistance to a range of chemicals. The Chemical Resistance Guide (CRG) combines DuPont Dow's experience with that of The Los Angeles Rubber Group. To register for the tool, visit the company's website (at www.dupont-dow.com/crg).

Composite results

Composites are also racing forward, thanks largely to their use in high technology industries such as aerospace and Formula One. This is a field where composite structure – the types of materials used – is an important factor in performance improvement. But another important strand of the innovation is the way in which the materials are processed.

One technique – developed in the UK but since been taken up by major car manufacturers – is MIT (Multiple Insert Technology) from Cornwall-based Plastech TT. The technique – which produces 'soft' tools that can be used to make composite parts quickly, cheaply and cleanly – surfaced around three years ago, but has since been developed and commercialised. It has been awarded Millennium Product status.

Moulding composite parts is traditionally a relatively slow process, with the mould preparation and cleaning stages acting as particular bottlenecks. So in place of a single mould – which must be treated before and after moulding – MIT produces multiple, low cost mould faces that can be taken off the production line once they have been used. This means there is no hold-up to the production cycle.

"Conventional moulding is like taking a taxi ride," says Plastech TT managing director Alan Harper. "You know you'll have to pay at the end regardless of time wasted in traffic hold-ups. With MIT, there is no hold-up and optimum production speeds can easily be met." The technique was recently used in the US to produce the roof for a truck cab. Cincinnati Fiberglass, based in Ohio, says that it can now produce 85 parts per day from one MIT mould, compared with 35 parts per day using conventional technology.

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