Azodicarbonamide
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Azodicarbonamide, ADCA, ACA, ADA, or azo(bis)formamide, is a chemical compound with the molecular formula . It is a yellow to orange-red, odorless, crystalline powder. It is sometimes called "the yoga mat chemical" because of widespread use in foamed plastics. It was first described by John Bryden in 1959.
Azodicarbonamide, ADCA, ACA, ADA, or azo(bis)formamide, is a chemical compound with the molecular formula . It is a yellow to orange-red, odorless, crystalline powder. It is sometimes called "the yoga mat chemical" because of widespread use in foamed plastics. It was first described by John Bryden in 1959.
Synthesis
It is prepared in two steps via treatment of urea with hydrazine to form biurea, as described in this idealized equation: Oxidation of biurea with gaseous chlorine yields azodicarbonamide:
Blowing agent
The principal use of azodicarbonamide is in the production of foamed plastics as a blowing agent. The thermal decomposition of azodicarbonamide produces nitrogen, carbon monoxide, carbon dioxide, and ammonia gases, which are trapped in the polymer as bubbles to form a foamed article. Azodicarbonamide is used in plastics, synthetic leather, and other industries and can be pure or modified. Modification affects the reaction temperatures. Pure azodicarbonamide generally reacts around 200 °C. In the plastic, leather, and other industries, modified azodicarbonamide (average decomposition temperature 170 °C) contains additives that accelerate the reaction or react at lower temperatures. An example of the use of azodicarbonamide as a blowing agent is found in the manufacture of vinyl (PVC) and EVA-PE foams, where it forms bubbles upon breaking down into gas at high temperature. Vinyl foam is springy and does not slip on smooth surfaces. It is useful for carpet underlay and floor mats. Commercial yoga mats made of vinyl foam have been available since the 1980s; the first mats were cut from carpet underlay.
Food additive
As a food additive, azodicarbonamide is used as a flour bleaching agent and a dough conditioner in some countries such as the US and Canada (up to 45 ppm), but not in the European Union. It reacts with moist flour as an oxidizing agent. The main reaction product is biurea, which is stable during baking. Secondary reaction products include semicarbazide (aminourea) and ethyl carbamate (urethane). It is known by the E number E927. Many restaurants in the US fast food industry removed E927 from foodstuffs in response to negative publicity.
Safety and regulation
References
External links
International Chemical Safety Card
Text derived from https://en.wikipedia.org/w/index.php?oldid=1367569594 under CC BY-SA 4.0; modifications have been made.