Terephthalic Acid (TPA) Powder

Terephthalic acid (TPA), also written as C6H4(COOH)2 or 1,4-benzenedicarboxylic acid, is a white crystalline powder supplied at lab grade. It sublimes rather than melting cleanly, and that behavior is the basis of its main pyrotechnic use: it is a standard organic fuel in white smoke compositions, vaporizing and recondensing to give a dense, persistent obscurant with little residue.

It is generally preferred over older smoke agents for its lower toxicity and good thermal stability. Industrially, terephthalic acid is the bulk monomer used to make PET polyester resin and fiber.