The goal of this project was to set up a new route to recycle composites, which will decrease the cost of production waste disposal by 50%.
The whole composites sector is now aware of the environmental rules about wastes from composites production which apply to their industry. It concerns the directive on End-of-life Vehicles 2000/53/EC and directive 2002/96/EC on Waste Electrical and Electronic Equipment. The routes currently available are expensive and do not give the best use of the wastes, since they are mainly burnt. The heat generated by the combustion process, and the ashes in cement furnaces, are the main, low value, returns.
End products given by grinding reused in resins and polymers usually result in bad quality products. The consortium believes that it is possible to get a better route if the organic phase is converted to small molecules which can be used by the chemical industry and if the mineral phases can be used again in composites. The community wants to define the best conditions in order to obtain a physico-chemical (solvolysis) separation of the different components of the composite and to get the best commercial added value from the end products. In addition, to improve the general standard of competitiveness of the European composite community by reducing the waste management cost, the process will help the composite industry to comply with European regulations.
The project's first phase dealt with identifying the main composite waste resources in Europe. Production waste, end-of-life boats and end-of-life vehicles represent the most reliable sources. However, it should be noted that the collecting and dismantling network of composites in end-of-life products is still immature.
In the first phase also a laboratory prototype solvolysis reactor was designed and built. The process parameters identified as most influential are: temperature, processing time, pressure and composite mass/water volume ratio.
Numerous solvolysis trials have been carried out in order to determine the parameters window leading to the best recovered products. The first results showed that solvolysis allows the removal of up to 90% of the resin, to retrieve a liquid containing potentially interesting chemicals, and to recover glass fibres with a satisfactory aspect. The products obtained, in solid and liquid phases, were then analysed more thoroughly. Analyses of the liquid fraction show that the solution contains chemicals of potential commercial value (among which benzoic acid and some glycols). The analyses of the mechanical performances of the recovered glass fibres show that the mechanical properties are best preserved when operating at low temperature and shorter reaction times.
During the second phase of the project, a large scale prototype reactor was designed and built. New solvolysis trials could be started, based on the optimised set of parameters identified during the trials on the laboratory scale reactor. Due to the new size of the reactor and to the different phenomena involved at this scale, some of the parameters had to be adjusted to obtain recycled fibres with sufficient mechanical properties.
A life cycle assessment was conducted thanks to the data gathered on the large scale reactor. It reveals that the solvolysis process is not yet competitive with treatments like mechanical recycling or energy recovery, but can possibly be competitive with pyrolysis in terms of environmental impacts.
A different way to recycle fibre-reinforced thermoset composites: the EURECOMP project has developed a physico-chemical separation and recovery process called 'solvolysis', in order to recover the mineral fibres as a reusable reinforcement in new composite parts, as well as to convert the organic phase into small molecules that could be reused by the chemical industry.
To provide a global view of the feasibility of composites recycling through solvolysis, upstream and downstream fields and markets have been investigated. The process was evaluated in terms of financial viability and environmental impact, the final markets and users were investigated and questioned.
Innovating for the future (technology and behaviour):
• Promoting more sustainable development
• A European Transport Research and Innovation Policy
The project has assured that knowledge was gained on the solvolysis technology applied to thermoset composites. However, the process still needs improvements before a new industrial scaling up, in order to be economically more competitive.