tions. In Europe, it is estimated that composite waste in 2025 will amount to about 680 thousand tonnes, broken down as in Figure 1. The sectors that generate the largest shares, evidently, are the same ones that consume the highest quantities of materials. Composite waste management entails major challenges. This is due to the often complex structure of the components, but above all to the coexistence of two constituent materials: the polymer matrix and the reinforcing fibres. Furthermore, in most cases, the polymer matrix is made up of thermosetting resins which, once cured, are difficult to recycle due to their chemical characteristics, which does not allow thermal reprocessing. Thermoplastic resins, on the other hand, can be remelted |
or thermally softened. Although the latter currently represent 40 % of the composite market, they were scarcely used before the 1990s( source: JEC Group, 2024), so almost all of the oldest composite products which are going to be disposed of today have a thermosetting matrix. From a regulatory point of view, the Landfill Directive 1999 / 31 / EC introduced disposal restrictions, starting from 2030, for all types of waste potentially suitable for recycling or energy recovery. Composites fall into this category, due to the high calorific value of the polymer matrix. Some European countries have got a head start, implementing disincentives or outright bans on the disposal of end-of-life composites in landfills. The scenario described highlights the need for efficient and effective solutions to increasingly promote the circularity of composites compared to the linear model of production and consumption.
END-OF-LIFE VS ECO-DESIGN The end-of-life approach involves existing products which have reached the end of their useful life. The possible end-of-life solutions are: incineration( energy recovery), recycling( material recovery), or reuse in the same or in other applications( recovery of components). However, the best option in this“ waste hierarchy”, as defined in the European Directive 2008 / 98 / EC, is to prevent the production of waste upstream. This can be achieved with a proactive approach known in general as eco-design. This method includes a series of strategies that designers can adopt to improve the environmental performance of products, such as reducing
|
the use of materials or selecting low-impact materials, optimizing production techniques, product durability or end-of-life treatment. CETMA( Brindisi), a contract research organisation offering advanced engineering services, is working on both approaches in the framework of two European projects focused on the wind energy sector, which covers a significant share of the EU composites market.
ECO-DESIGN APPROACH: THE MAREWIND PROJECT The Horizon 2020 Marewind project( 2020-2024) deals with the development of new materials for nextgeneration wind turbines with improved performance in terms of circularity. New materials with a higher recycling potential than traditional thermosetting resins were investigated. Among these, reactive thermoplastic resins and recyclable epoxy resins are particularly interesting. A reactive thermoplastic resin is a low molecular weight oligomer that is polymerized in situ, resulting in a thermoplastic material that can be then reprocessed thermally, and therefore also recycled using thermal processing techniques. On the other hand, an epoxy resin can be made recyclable by reacting it with a suitably engineered amine hardener, which has internal bonds that can be split in a solution( solvolisis). In this case, therefore, the recycling method is chemical. Under low temperature and acidity conditions, it is possible to recover the reinforcing fibres and the matrix separately in the form of a decrosslinked polymer. Based on preliminary results of laboratory-scale recy-
|
Italian technology plast / April 2025 |
||
www. plastmagazine. it |
047 |