N,N-Diethylaniline (DEA)

N,N-Diethylaniline (DEA) is a tertiary aromatic amine accelerator used in BPO/amine cobalt-free cure systems for unsaturated polyester resins, providing a slower acceleration rate than DMA or DMPT and enabling longer working times in hot conditions. The ethyl groups on nitrogen in DEA are bulkier than the methyl groups in DMA and DMPT, which slightly reduces the electron-donating ability and the reactivity with BPO, resulting in slower radical generation and extended gel times. This makes DEA particularly useful for large castings, thick laminates, or work in warm ambient conditions (25–35°C) where DMA or DMPT would produce excessively short pot lives. DEA is also used in certain polyester adhesive formulations. Typical dosage is 1–3% DEA combined with 2–4% BPO paste (50%), providing gel times of 20–45 minutes at 20°C. Compared to DMA, DEA contributes slightly less discoloration in cured systems. DEA is a colorless to pale yellow liquid with an amine odor. It shares the general toxicity profile of aromatic amines — potential carcinogen classification, skin absorption risk — requiring PPE and workplace ventilation equivalent to DMA.