Triethylenetetramine
Triethylenetetramine is a workhorse aliphatic amine: inexpensive, fast and highly reactive with epoxy at room temperature, and a building block for many modified hardeners.
TETA is a linear ethyleneamine with two primary and two secondary amine groups (molecular weight 146.24 g/mol), giving six reactive N–H hydrogens and an AHEW of about 24. Commercial TETA is a mixture of linear, branched and cyclic isomers. It is a yellowish liquid with an ammonia-like odor that boils at about 267 °C. The same molecule is used medically as trientine.
TETA cures epoxy resins at ambient temperature in adhesives, laminating systems, castings and economical coatings. Because neat TETA gives short pot life, high exotherm and a blush-prone surface, it is more often used to make adducts, polyamidoamines and Mannich bases that are easier to apply.
With six active hydrogens on a small molecule, TETA builds a tightly crosslinked network quickly.
TETA is corrosive to skin and eyes, harmful in contact with skin, a skin sensitizer and harmful to aquatic life. Use chemical-resistant gloves, eye and face protection and ventilation, and avoid breathing vapors from warm material. Store tightly closed under dry conditions to limit reaction with air.
Its AHEW is only about 24, so a small mass supplies many reactive hydrogens. With a standard liquid epoxy resin, stoichiometry is roughly 13 parts TETA per 100 parts resin.
DETA (diethylenetriamine) is smaller and more volatile, with an AHEW of about 21. TETA is slightly less volatile and less reactive, but both give fast, rigid, blush-prone cures and are widely used to make modified hardeners.
Pot life is short, exotherm is high and the surface blushes easily. Adducting TETA with some epoxy or converting it to a polyamidoamine improves handling and appearance.
