Structural Adhesive Bonding of Vacuum-Infused Acrylic-Based Thermoplastic Fibre-Reinforced Laminates

Driven by regulatory and environmental demands, composite structures must combine high structural performance, recyclability, and resource efficiency. Here, an investigation on the structural adhesive bonding of glass-fibre-reinforced thermoplastic Elium© composite laminates is undertaken. Substrates are manufactured using vacuum infusion. Evaluation is performed on the following three commercial two-component adhesives cured at RT: an epoxy (EP), a polyurethane (PU), and an acrylate system (AC). Based on Dynamic Mechanical Analysis, the glass transition temperatures of the EP, PU, and AC adhesives are 56.5, 102.9, and 111.9 °C, respectively. The AC adhesive exhibits the highest shear strength and displacement at failure, reflecting a superior load-bearing capacity. Fractographic analysis further supports these findings: AC joints show a mixed substrate/cohesive failure mode, while EP samples fail exclusively by adhesion failure and PU samples predominantly by a mixture of special cohesion, adhesion and substrate failure. Regarding processing, the EP samples show the highest pot life, followed by PU and then AC. Nonetheless, the pot life of the AC adhesive does not limit its range of application.. The results highlight the advantages of adhesive bonding of Elium© in enabling lightweight and more circular composites. RT-cured adhesives eliminate the need for drilling and energy-intensive thermal curing, allowing design flexibility and reductions in CO2 footprint within composite production.