Radikaalikäynnistys

Radikaalikäynnistys refers to a method used in chemical reactions to initiate polymerization processes. It involves the generation of highly reactive species, known as radicals, which then trigger the chain reaction of monomer molecules linking together to form polymers. These radicals typically have an unpaired electron, making them unstable and eager to react with other molecules.

Common initiators for radical polymerization include organic peroxides, azo compounds, and certain metal salts. For example, benzoyl peroxide decomposes upon heating to form phenyl radicals. These radicals then attack a monomer molecule, adding to its double bond and creating a new radical species on the monomer. This process continues in a chain reaction, with the radical end of the growing polymer chain reacting with subsequent monomer units.

The rate of radical generation and the concentration of radicals are crucial factors influencing the polymerization rate and the molecular weight of the resulting polymer. Temperature also plays a significant role, as it affects the decomposition rate of the initiator and the reactivity of the radicals. Radikaalikäynnistys is a widely employed technique in the industrial production of many common plastics and polymers, such as polyethylene, polystyrene, and polyvinyl chloride. Control over the initiation process allows for tailoring the properties of the final polymeric material.