New technology could tackle a growing problem for automotive, construction and other major industries - how to recycle composite plastics.
Forthcoming legislation sets increasingly stringent targets for recovery of composite materials, used for highly-engineered components such as car bumpers and fascias. The high tech plastics are lightweight and durable, but difficult to recycle, which is a major problem as the European End-of-Life Vehicle directive requires manufacturers to recycle 85% of plastics, rubber and glass by 2006 and 95% by 2015.
Scientists from the University of Leeds, UK, working with partners from British industry, have come up with a new solution that could aid manufacturers and save growing quantities of composite waste going to landfill. Composites are converted into their original constituents - oil and fibre - which can be recycled. The process could open up new applications for advanced composites by making recycling possible.
The two year research project formed part of a major waste minimisation initiative backed by government and industry. The WMR3 LINK programme (Waste Minimisation through Recycling, Recovery and Re-use in Industry) is spearheading new ways to clean up the environment and make better use of resources.
‘Until now, fibre reinforced polymer composites have been widely considered un-recyclable,’ says Professor Paul Williams of the University of Leeds, Department of Fuel and Energy. ‘That has been a major headache for the motor industry in particular. Most of the car, including the tyres, metal and glass can be recycled quite easily, but composites are much more difficult because the material is reinforced.’
The new recycling process combines pyrolysis and physical separation. Composites are broken down into gas, oil, a small amount of carbon and fibre. Recycled oil and fibre can both be reprocessed into composite plastics. The Leeds University team are experts in pyrolysis and have worked for a number of years on different waste streams, including tyres and plastics.
‘Pyrolysis involves heating the plastic in the absence of oxygen, so that it does not burn,’ explains Professor Williams. ‘Because the process operates at a much lower temperature than burning, fibre retains much of its original strength, instead of becoming brittle. Our research shows that both the oil and the fibre can be processed back into composite plastics or re-used in other ways.’