Why is organic peroxide a hazard?

From a first aid perspective, depending on the material, route of exposure (inhalation, eye or skin contact or swallowing) and dose/amount of exposure, organic peroxides can cause harm.

As part of the training process, you should fully understand the hazards associated with the organic peroxide(s) you are going to be working with and adopt the appropriate working practices. Risks will be outlined in the Safety Data Sheet (SDS) and  some will be detailed on the product’s labelling. You should also consult with the supplier/manufacturer of the material.

In terms of infrastructure and the environment, the main hazards associated with organic peroxides are fire and explosion, but they can also be toxic and corrosive. It is the two oxygen atoms (-0-0-) joined together that make organic peroxides hazardous (and at the same time useful). Because they are chemically unstable the compound can easily decompose, giving off heat which increases as the temperature rises. Most undiluted organic peroxides catch fire, burning rapidly and intensely. Many give off flammable vapours when they decompose which can easily combust. Some organic peroxides are dangerously reactive, decomposing very rapidly or explosively if they are exposed to only the slightest amount of heat, friction, mechanical shock or contamination with incompatible materials.

Organic peroxides can also be strong oxidizing agents. Combustible materials contaminated with most organic peroxides can catch fire easily and burn very intensely (deflagrate). The burn rate can range from one metre per second to hundreds of metres per second. The combustion rate increases as the pressure increases and the combustion zone can travel through air or a gaseous medium faster than the speed of sound. However, the speed of combustion in a solid medium does not exceed the speed of sound.

Deflagration (an explosion in which the speed of burning is lower than the speed of sound in the surroundings) and detonation are similar chemical reactions except that in a detonation the burn rate in a solid medium is faster than the speed of sound. This supersonic speed results in a shock wave being produced which can reach speeds of around 2,000 to 9,000 metres per second and is not dependent on the surrounding pressure.

Organic peroxides may also have a self-accelerating decomposition temperature (SADT). This represents the lowest temperature at which the organic peroxide formulation still in its commercial packaging will undergo self-accelerating decomposition (begin the chemical process that leads to explosion). The SADT value will vary from formulation to formulation and also depends on the size and shape of the packaging. Storage requirements will generally be 10º to 20º below the stated SADT.

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