Investigation of thermolabile particles for debonding on demand in fiber reinforced composites

Glass fiber reinforced plastics (GFRP) are essential for lightweight design and are manufactured in high quantities. Since there is no suitable method for recycling, the GFRP are mostly grinded and used as filler at end of life. In this work, the well-known principle of debonding on demand is considered to enable feasible and value-retaining separation of glass fibers from the polymeric matrix. To this end, gas-releasing thermo-responsive substances (TRS) like carboxylic or amino acids are introduced to the composite to investigate their potential for causing delamination after heating. To promote sufficient fiber/matrix adhesion, the TRS are encapsulated with silica or immobilized on magnetite particles. Furthermore, the immobilization synthesis is scaled up by using a custom-made continuous flow reactor. Finally, a new sizing mixed for glass fiber spinning, containing the particles, is formulated. The experiments reveal that a maximum of 0.5 wt.% particles can be used in the sizing to coat the fibers. Although all tested samples show a significant organic functionalization, the particles functionalized with TRS do not trigger sufficient delamination at the current state of development.