Organic peroxides are a group of chemical compounds used in the manufacture of a variety of plastics and construction materials, as well as in some pharmaceuticals and skin treatment products. The plastics and rubber industries are the main users of organic peroxides and mixtures containing an organic peroxide, these are used as accelerators, activators, catalysts, cross-linking agents, curing agents, hardeners, initiators and promoters.
What you should know about organic peroxides is that unlike most other chemicals, the purpose of a peroxide is to decompose, which generates useful radicals that can form polymer resins such as polyester and silicone, to make fiberglass and other products. Terms such as accelerator, activator, catalysts etc. are also used to describe some other materials that do not contain organic peroxides which could lead to confusion and increase the risk of an accident if these substances were inadvertently mixed with organic peroxides.
Organic peroxides are normally available as solids (usually fine powder), liquids or pastes. Some materials, such as water, odourless mineral spirits, and some phthalate esters do not react with organic peroxides and are often used to dilute them. The diluted mixture (makes handling and use safer) or formulation is less likely to explode when exposed to heat or physical shock than the undiluted organic peroxide.
An organic peroxide is any organic (carbon-containing) compound having two oxygen atoms joined together (-O-O-). This chemical group is called a “peroxy” group. Organic peroxides can be severe fire and explosion hazards and a number of them are thermally unstable meaning they have to be stored at cold temperatures. It is therefore imperative that the recommended storage and handling practices are adopted to effectively reduce the risk of fire and or explosion.
In the event of a fire, safety advice normally recommends using water spray, dry chemical, or carbon dioxide as the extinguishing media. Water is recommended for controlling and containing peroxide fires since it will provide better cooling and reduces the rate at which the peroxide decompose and thereby reduces the energy that feeds the fire. It should be noted that water will not extinguish an organic peroxide fire as most organic peroxides are lighter than water and can burn on liquid surface. Any fire will most likely resemble a petrol fire, which could be explosive and intense.
Organic peroxides decompose to form gases including hydrocarbons and some alcohols, much of these would normally burn off in a fire that results from the organic peroxide decomposition, but some may be carried away in the smoke which and be released into the atmosphere and dissipate.
Some organic peroxides also contain solvents which are used to dilute the product, the solvents used are odourless mineral spirits similar to diesel fuel, in the event of a fire the by-products would be similar to those seen in a diesel fuel.
In terms of human health, direct exposure to organic peroxides can cause eye, skin and/or respiratory irritation as well as nausea, drowsiness or dizziness. In case of exposure, consult the SDS (Safety Data Sheet) seek on site medical assistance and/or call 999 for an ambulance.