Used primarily as a curing agent in epoxy resins, especially in electrical insulation applications such as transformers, generators, and motors. Its anhydride structure allows for controlled reactivity with epoxy groups, resulting in thermoset polymers with good mechanical strength, thermal stability, and low dielectric constants. Commonly chosen for high-voltage systems due to its ability to form void-free, moisture-resistant coatings when cured. Also utilized in composite materials and encapsulants where long-term reliability under thermal cycling is required.