Optically transparent and high-strength glass-fabric reinforced composite

Fiber reinforced polymer composites (FRPs) are widely utilized in various industrial applications due to their significant advantages such as low cost and superior mechanical properties. However, owing to the trade-off between high mechanical strength and high optical transparency with typical FRPs, it is technically challenging to achieve high mechanical performance while meeting the optical requirements for transparent electronics and automotive applications. We herein report the synthesis of a transparent fiber reinforced polymer (tGFRP) by incorporating reinforced E-glass fiber into refractive-index-tunable thermosetting epoxy resin and the consequential advantageous opto-mechanical properties. By doping organic molecules, the optical property of the epoxy-based resin system has been efficiently engineered, achieving the match of the chromatic dispersions of the E-glass fiber and the epoxy resin. By the means of a novel technique derived from infusion treatment and in-situ polymerization combined with a liquid composite molding (LCM) method, both surface and bulk defects have been efficiently mitigated. With the refractive-index of the epoxy matrix matched with that of the embedded fiber fabrics, high transparency up to 88% has been realized with 10v.% fiber loading (500 μm thick tGFRP). An outstanding transparency and superior mechanical properties were achieved on 2 mm thick samples, maintaining up to 85% transmittance even when using 25 layers of E-glass fabric, corresponding to 50 v.% fiber. This work has shed light on the development of transparent composite materials for applications such as in construction, transportation, and protective equipment.