N,N-Dimethylaniline (DMA)

N,N-Dimethylaniline (DMA) is a tertiary aromatic amine accelerator used in combination with benzoyl peroxide (BPO) to achieve ambient-temperature, cobalt-free cure of unsaturated polyester and vinyl ester resins. DMA is one of the fastest-acting amine accelerators available — when combined with BPO paste, it produces very short gel times (8–15 minutes at 20°C with standard dosages), making it suitable for fast-cure applications. The mechanism involves electron transfer from DMA's amine nitrogen to BPO, generating benzoyloxy and phenyl radicals that initiate free-radical polymerization. DMA provides slightly faster acceleration than DMPT but can contribute more yellow discoloration to cured laminates and gelcoats due to oxidation of the aniline ring. Typical dosage is 0.5–2% DMA combined with 2–4% BPO paste (50%), providing gel times from 5 to 25 minutes at 20°C. DMA is a colorless to pale yellow liquid with a distinctive aromatic amine odor. It is classified as toxic (skin penetration) and a suspected carcinogen; appropriate PPE and ventilation are essential. Its use in food-contact applications is restricted.