Infrared Welding as an Efficient Joining Method for Sustainable Thermoplastic Composites

Thermoplastic composites are gaining attention due to their recyclability, high toughness, and ability to undergo fusion bonding. This study investigates the use of infrared radiation (IR) for welding acrylic resin-based thermoplastic composites reinforced with carbon and glass fibers. The Elium® 150 resin was selected for its hybrid thermoset-thermoplastic properties, enabling room-temperature polymerization and reprocessing. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) determined a glass transition temperature of 94 °C and degradation onset at 204 °C (1% mass loss in air). Lap shear tests were conducted to evaluate the mechanical performance of welded joints at different temperatures (150 °C, 175 °C, and 200 °C) and pressures (0.4 MPa and 0.5 MPa). The highest lap shear strength was observed at 150 °C and 0.5 MPa, with values of 9.59 ± 1.60 MPa for carbon fiber and 13.72 ± 4.76 MPa for glass fiber composites. Fractographic analysis using scanning electron microscopy (SEM) identified adhesive and cohesive failure modes. Results indicate that infrared welding provides a promising, rapid, and contamination-free technique for joining thermoplastic composites, with glass fiber-reinforced laminates showing superior adhesion compared to carbon fiber composites. These findings contribute to the development of lightweight, recyclable composite structures for aerospace, automotive, and wind energy applications.