Definition - What does Polyamine mean?

Polyamine refers to a compound that consists of at least two amino groups. It is a highly charged, low molecular weight aliphatic polycation. In the atmospheric corrosion of mild steel, this compound acts as a corrosion inhibitor. Polyamines are also important chelating agents.

Polyamines are produced in nature as well as synthetically. Synthetic polyamines are used for industrial applications like the manufacture of other chemicals in the chemical industry. The synthetic polyamine ethylenediamine (EDA) and its derivatives are used in the manufacture of paint, coolant and polyester, and in the process of electroplating and photograph development.

Corrosionpedia explains Polyamine

Polyamine is one of the key active components in boiler treatment technology. It is multifunctional, volatile, and acts as a corrosion inhibitor. In boiler treatment, a polyamine provides protection against metallic corrosion all over the boiler system.

Polyamines like ethylenediamine (EDA) are used to control acid corrosion in petroleum distillation columns. Here it is used in conjunction with a corrosion inhibitor. The polyamines form a film on the metal surfaces, thereby controlling corrosion. They also act as a sludge conditioner.

Polyamines such as mexamethylenediamine (C6H16N2) are also used to produce nylon, polyester and a few kinds of polyurethane in the industry. Some polyamines are used as co-reactants (hardeners) with epoxy resins on a large scale. Most aromatic polyamines are crystalline solids at room temperature. Some varieties of polyamines include:

  • Piperazine – a cyclic polyamine
  • Cyclen and cyclam – macrocyclic polyamines can bind anions
  • Polyethylene amine – a polymer based on the aziridine monomer

Polyamines have great use as chelating agents. Tetramethylethylenediamine (TMED) is suitable for dissolving metal ions in organic solvents. Cyclams add cavity selectivity to the chelate effect. Diethylenetriamine (DETA or dien) and triethylenetetramine (TETA or trien) are more powerful chelating agents and they form tridentate and tetradentate complexes, respectively.

Polyamine-based hardeners are used to cure epoxy resins at room temperature. These hardeners are made from an organic molecule consisting of two or more amine groups. They are used by the composites industry. Polyamine hardeners are corrosive and some are moderately toxic to the skin.

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