Poly(azelaic anhydride) (PAA/PSA) Flexible Epoxy Curing Agent

PSA (polyazelaic anhydride) is waxy solid at room temperature (Tm 40–55°C) and must be melted at 60–80°C before mixing with epoxy resin. Hot-mix the two components at 70–80°C, then cast or apply; pot life at 80°C is 30–90 min. Cure at 120–150°C for 1–2 h to achieve full crosslinking. Accelerators: BDMA (1–2 phr) or 2E4MZ (1 phr); bismuth neodecanoate is acceptable for VOC-sensitive applications. The long aliphatic chain of PSA yields low-Tg, rubbery crosslinked networks with excellent cryogenic flexibility to -50°C.