Structural reuse offers a promising alternative to traditional composite recycling by keeping the original material intact and enabling it to be used again in new applications. Thermoplastic-reinforced composites, in particular, open the door to innovative reuse pathways — including reshaping components or returning them to flat laminate blanks.
In this study, we explored a technique called reverse forming for glass-fiber polypropylene (GF-PP) laminates. Our goal was to understand how these materials can be reshaped and reused while maintaining high performance. We developed a forming process, tested material behavior, and evaluated the effect of three key design factors:
- Forming strain – controlled by adjusting bending radius and contour depth, influencing how layers slide during deformation
- Laminate architecture – comparing orthogonal and quasi-isotropic layups to study resin flow and internal structure changes
- Material weave type – testing plain vs. twill fabrics to examine differences in layer movement and resin redistribution
GF-PP laminate blanks were pressed, reshaped, and then flattened again using moderate heat (<165 °C) and vacuum pressure in a novel moulding setup. The resulting samples showed strong mechanical performance, with flexural strength between 91–113 MPa and flexural modulus between 9–16 GPa. A Design of Experiments evaluation confirmed the robustness of the process within the tested conditions.
Overall, the results demonstrate that reverse forming is a viable pathway for reusing thermoplastic composite structures — especially when inter-ply slip governs deformation. These findings highlight both a practical manufacturing approach and important design considerations for enabling structural reuse in future composite components.
The full article was published in the Journal of Composites Part C:
Joustra, J., Brans, K., Villegas, I. F., Sinke, J., & Teuwen, J. (2024). Reverse forming thermoplastic composites: design and process development. Composites Part C Open Access, 100550. https://doi.org/10.1016/j.jcomc.2024.100550