tert-Butyl Peroxy-2-Ethylhexanoate (TBPEH)

tert-Butyl Peroxy-2-Ethylhexanoate (TBPEH), commonly known by trade names such as Trigonox 21, is a medium-temperature organic peroxide with a 10-hour half-life temperature of approximately 73°C. It is one of the most widely used initiators for warm cure and elevated temperature cure of unsaturated polyester and vinyl ester resins in the range of 80–130°C. TBPEH is particularly valued in pultrusion processes where consistent, controlled exotherm at die temperatures of 100–150°C is essential for high-quality profiles. It is also used in filament winding systems where parts undergo post-cure in an oven, and in RTM/VARTM processes that incorporate a staged warm cure cycle to achieve full crosslink density. The liquid form (clear, slightly yellow) makes it straightforward to meter and blend into resin systems. TBPEH can be combined with a high-temperature peroxide (TBPB) for dual-peak cure profiles in thick SMC sections. Typical dosage is 0.5–1.5% on resin for pultrusion and warm-cure applications. Store at or below 10°C to ensure shelf life integrity.