Hazardous polymerization
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221895742
2008-06-26T15:58:05Z
Itub
426390
[[Category:Polymerization reactions]]
[[Radical polymerization]] of pure [[styrene]] causes the [[viscosity]] to increase. This retards the deactivation of the [[free radical]]s by radical-radical reactions, but it does not have such a great effect on the reaction of the radicals with styrene. Hence the concentration of free radicals increases and the rate of reaction increases, which can lead to [[thermal runaway]]. While the [[autoacceleration]] seen with pure styrene is the classic example taught to [[chemistry]] [[undergraduates]], this effect can occur during the [[polymerization]] of other [[monomer]]s such as [[methyl methacrylate]].[http://www.chem.rochester.edu/~chem421/autoac.htm]
Avoiding thermal runaway is one of the reasons why [[suspension polymerization]] is such a popular way of making [[polystyrene]]. The droplets dispersed in the [[water]] are small reaction vessels, but the [[heat capacity]] of the water lowers the [[temperature]] rise, thus moderating the reaction.
[[Category:Polymerization reactions]]
[[Category:Chemical safety]]
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