Light relief for car recyclers

Novel spectrometer will help car makers meet legal requirement to reuse plastics

By Sue Stuckey

Compulsory recycling of components by car makers, due to be introduced in 2002, is creating a dynamic market for junk plastics.

Even commodity plastics such as polycarbonate, ABB and the nylons are attracting premium prices.

But here is the rub for recyclers: the polymer must be in a known pure form to be acceptable to the car makers.

Identification is a problem, according to John Amner, recycling specialist at Ford’s Dunton research centre. `The problems and cost penalties of getting it wrong mean the recycling companies will only handle one or two types of material,’ he says.

Now that car companies will be the recyclers under the legislation, they are looking for better identification methods. Sniffing the fumes from a lump of burning polymer is the traditional method, but it is unreliable.

Amner, working alongside researchers at Southampton University, has developed test equipment that can identify most packaging materials and all the automotive plastics used within Europe. And it is also attracting interest from the police for forensic work.

The PolyAna infrared spectrometer costs £20,000 but, unlike other spectrometers, which are laboratory-based, this one can work out of the back of a van. And it is fully automatic, giving a precise analysis of the plastics content as well as the type of filler materials and even the name of the producer from a unique tracer within the material.

Plastics produce a unique light scatter pattern, or spectragraph, previously needing a chemist to provide an interpretation.

Optics developed by Amner and his team turn an ordinary spectrometer into a fully automatic test device that can be used and understood by anyone.

Special software speeds up identification from a database of most commonly used plastics.

Six special mirrors deflect the infrared beam on to the component. Using the same path, scattered light returns to the spectrometer for analysis.

`Previously, the only way you could identify a material was to break off a piece and put it inside the spectrometer,’ says Amner. There was no way to get the light beam outside the cabinet.

PolyAna can non-destructively test new parts as well as old ones.

A car contains around 8% by weight of recycled material from a total plastics content of around 55kg. Wheel arches, under body pans, air cleaners and various small covers are all made from recycled plastics.