Azodicarbonamide, ADCA, ADA, or azo(bis)formamide, is a compound with the molecular formula C2H4O2N4. [1] It is a yellow to orange-red, odorless crystalline powder. It is sometimes called the "yoga mat" chemical because of its widespread use in foam. [2][3] It was first described by John Bryden in 1959.

It is prepared in two steps by treating urea with hydrazine to form diurea, as described by the following idealized equation:

2 O=C(NH2)2 + H2N−NH2 → H2N−C(=O)−NH−NH−C(=O)−NH2 + 2 NH3

Oxidation with chlorine or chromic acid yields azodicarbonamide:

H2N−C(=O)−NH−NH−C(=O)−NH2 + Cl2 → H2N−C(=O)−N=N−C(=O)−NH2 + 2 HCl

The main use of azodicarbonamide is as a blowing agent in the production of foamed plastics. The thermal decomposition of azodicarbonamide produces nitrogen, carbon monoxide, carbon dioxide, and ammonia, which become trapped in the polymer as gas bubbles, forming foam products. [5]

Azodicarbonamide is used in plastics, synthetic leather and other industries, and it can be pure or modified. The modification affects the reaction temperature. Pure azodicarbonamide typically reacts at around 200 °C. In plastics, leather and other industries, modified azodicarbonamide (average decomposition temperature 170°C) contains additives that accelerate the reaction or react at lower temperatures. [5]

An example of the use of azodicarbonamide as a blowing agent is found in the manufacture of vinyl (PVC) and EVA-PE foams, which form bubbles when decomposed into gas at high temperatures. Vinyl foam is resilient and won't slide on slippery surfaces. It can be used in carpet underlays and floor mats. Commercial yoga mats made of vinyl foam have been available since the 1980s; the first mats were cut from carpet underlayment.