Class 5.2: Organic Peroxide Based Hazardous Substances

General Information:

Class 5.2 (Organic Peroxides) are some of the most unstable chemicals you can handle. This is because they carry both their own fuel and their own oxygen in the same molecule, meaning they can burn or explode even in a vacuum. They are highly sensitive to external triggers such as heat, friction, impact or even minor contamination from dirt or other chemicals. If they catch fire, they burn with incredible speed and can't be smothered. The only way to stop the reaction is to drench them with massive amounts of water to cool them down.

Main Hazards:

• May explode.
• Will burn rapidly.
• May be sensitive to impact or friction.
• May react dangerously with other substances.
• May cause damage to eyes.
• May be corrosive when in contact with skin.

Examples:

• Methyl Ethyl Ketone Peroxide (MEKP) - This acts as liquid catalyst that is used by hobbyists and manufacturers to harden resins for boats, surfboards and plastics. It's extremely sensitive to shock and heat and unstable to the degree that even a few drops of contamination or small temperature increase can cause a violent chemical reaction that releases intense heat and toxic fumes.
• Benzoyl Peroxide - This is most commonly found as a "hardening agent" or "activator" in car body filler (like Bondo) and fibreglass repair kits. It initiates the chemical reaction that turns liquid resins into solid plastic, but is highly sensitive to heat and friction. If it dries out or the temperature increases too much, it can catch fire or explode on its own.