2-Butanone peroxide, commonly known as methyl ethyl ketone peroxide (MEKP), is primarily used as a radical initiator and curing agent for unsaturated polyester resins in the production of fiberglass reinforced plastics, composites, and other reinforced materials. It facilitates cross-linking reactions at ambient temperatures when used with accelerators, enabling hardening in applications such as boat building, automotive parts, and corrosion-resistant coatings. Additionally, it serves as an initiator in the free-radical polymerization of vinyl monomers like styrene (for polystyrene) and methyl methacrylate (for acrylics). Commonly applied in casting, molding, laminating, and repair processes in the plastics and composites industries. Due to its high reactivity and potential for explosive decomposition, it requires careful handling, storage away from heat, friction, shock, and incompatible materials, and compliance with safety regulations.