Safety Aspects of Organic Peroxides
Organic peroxides are thermally unstable due to the relative weak O-O bond in the molecule. As a result organic peroxides are sensitive to heat and will decompose above a certain temperature in a runaway reaction. This temperature is specific to each individual peroxide and depends also on the packaging size.
During decomposition heat is released and the rate of decomposition increases with the temperature. If this heat cannot be transferred to the environment due to reduced surface area from stacking or high ambient temperatures, self-heating will accelerate and lead to a violent combustion or thermal explosion.
Every packed peroxide has a characteristic temperature at which the self-heating accelerates. This is designated as the Self-Accelerating Decomposition Temperature (SADT). At or above this temperature a runaway reaction will take place. For this reason heat exposure should be prevented and strict temperature control and high temperature alarms are required for the storage of organic peroxides. For many peroxides refrigerated facilities are necessary.
Contamination may accelerate the decomposition of organic peroxides. Most heavy metal compounds have an accelerating effect on decomposition. Acids, bases and accelerators based on cobalt or amines, may cause decompositions to occur at temperatures significantly below the recommended storage temperature. Therefore, organic peroxides must not be mixed with or stored with other chemical compounds, unless compatibility has been proven.
Organic peroxides are combustible, and some formulations are flammable. Although most peroxides are hard to ignite, once ignited most organic peroxides burn vigorously with burning rates faster than most organic solvents. When heated to their decomposition temperature, organic peroxides will generate vapors of decomposition products. Most of these products are flammable. Therefore the presence of ignition sources must be avoided. Electrical equipment installed should be explosion proof to avoid sparks. Nevertheless, auto-ignition of the vapors may still occur.
Organic peroxides produce vapors during decomposition. This can result in pressure build-up. The rapid increase in pressure may cause explosive rupture of containers, vessels or other equipment.
The original package is tested according to the UN regulations for safe transport and storage of dangerous goods. To prevent excessive pressure rise all facilities should be adequately designed (e.g. provided with a pressure relief mechanism) and segregated to protect personnel and surrounding facilities.
Storage of Organic Peroxides
Due to their specific properties organic peroxides cannot simply be put in any chemical stock-room for chemicals. Separate storage facilities are recommended. The separate storage and the requirements for such a storeroom have the same underlying principles.