CIRCE: an innovative method to recover uncured preimpregned composite scraps

Alessio Vita, Iacopo Bianchi – Università Politecnica delle Marche
Vincenzo Castorani – HP Composites
Valerio Alessi – Alci
Rosario Dotoli – CETMA
Lucia Delledonne – Petroceramics
Damiana Cafagna – Base

This project has been awarded by Compositi’s editorial staff and technical-scientifical Commitee!

Composite materials market is constantly expanding as a result of the increasing demand for lightweight products characterized by high engineering properties. The growing demand of Carbon Fiber Reinforced Polymers (CFRPs) raises some issues related to the relevant environmental impacts of their manufacturing processes. In particular, the environmental footprint is mainly determined by the high energy consumption required for the production of raw materials that, according to recent studies, account for about 90% of the total impacts (Duflou et al. 2012).

Therefore, in the next years, as the CFRP waste production is expected to increase, recovery and recycling systems to maximize the end-of-life value of these materials are highly necessary. For what concerns the recovery systems of thermoset-based composites, which constitute around 80% of the total reinforced polymers market (Mishnaevsky et al. 2017) loads, as well as available materials, are reviewed.
 

Recycling is not always an available or convenient option

Apart from the traditional composites for wind turbine blades (glass fibers/epoxy matrix composites), there are still relevant concerns. As a matter of fact, once the cross-linked structure of thermoset matrices is formed, it cannot be melted and reshaped (Wang et al. 2018), so recycling is not always an available or convenient option.
 

Circular Economy Model for Carbon Fibre Prepregs

A possible solution has been proposed within the CIRCE (Circular Economy Model for Carbon Fibre Prepregs) EU LIFE project (LIFE ENV/IT/000155), developed as a collaboration between five Italian companies (HP Composites, Alci, Base Protection, CETMA, and Petroceramics).

The goal of CIRCE is to set up a circular economy model for uncured thermoset prepreg scraps. Prepreg is one of the most widely used raw materials in composite industrial applications and it is constituted by pre-impregnated composite sheets where fibers are embedded in a thermosetting matrix.

Composite parts are created by stacking and curing several layers of prepreg sheets that are previously cut in the desired shape. During the cutting operations of virgin prepreg rolls waste are produced in form of off-cuts, trim waste, and end-roll waste. These waste constitute between 20 and 50% of the virgin prepreg used and they typically end up in landfill or incinerator (Nilakantan et al. 2014).

The companies involved in the project developed an industrial process to prepare the scraps and to use them as raw secondary materials, reaching a 100% valorization of the waste. The innovative recovery process is based on two machines, developed by Alci, in order to select, resize and transform the fabric prepreg waste in the ready-to-use secondary material.

This machine, by exploiting a physical process based on the friction generated on the backing paper surfaces, easily removes the film from both the faces of the chips. Three possible applications of the recovered material have been proposed within the CIRCE project and are currently under development.