tert-Butyl Peroxybenzoate (TBPB, 98%)

tert-Butyl Peroxybenzoate (TBPB) is a high-temperature organic peroxide initiator with a 10-hour half-life temperature of approximately 100°C. It is the preferred cure initiator for SMC (Sheet Moulding Compound) and BMC (Bulk Moulding Compound) compression molding at press temperatures of 140–165°C, where it provides a controlled exotherm, good flow and cure balance, and excellent surface quality in Class A automotive parts. TBPB decomposes to yield benzoyloxy and tert-butoxy radicals at processing temperatures, efficiently initiating crosslinking of the UPR/styrene matrix. Compared to DCP (dicumyl peroxide), TBPB provides a faster cure at equivalent temperatures with less residual odor in the cured part. It is often used in conjunction with a low-temperature co-initiator such as TBPEH for dual-peak cure profiles in thick SMC sections. The 98% purity liquid form simplifies dosing in automated SMC compound mixers. Typical dosage is 0.5–1.5% on resin. TBPB is also used as a post-cure agent in UPR lamination when elevated temperature post-cure is applied to achieve maximum mechanical properties.