FREE-RADICAL ADDITION CHAIN-GROWTH POLYMERIZATION

FREE-RADICAL ADDITION (CHAIN-GROWTH) POLYMERIZATION [Pg.146]

One of the most important types of addition polymerization is initiated by the action of jree-radicals, electrically neutral species with an unshared electron. Free-radicals are highly reactive and these types of polymerizations begin with the formation of ffee-radicals by an initiation reaction. In the developments to follow, a dot ( ) will represent a single electron or free-radical. The single bond, a pair of shared electrons, will be denoted by a double dot ( ) or, where it is not necessary to indicate electronic configurations, by the usual covalent bond sign (—). A double bond, two shared electron pairs, is indicated by or =. [Pg.146]

Free-radicals for the initiation of addition polymerization are usually generated by the breakdown of a chemical initiator. These initiators are classified by the method used to catalyze the breakdown thermal initiators, redox initiators, or photo initiators. [Pg.146]

Thermal initiators form free-radicals by the thermal decomposition of compounds such as organic peroxides or azo compounds. Two common examples of thermal initiatars are benzoyl peroxide and azobisisobutyronitrile [Pg.146]

To start these reactions, moderately high temperatures (70-100 °C) are needed. [Pg.146]

Free-Radical Addition (Chain-Growth) Polymerization [Pg.135]

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