✍ Scribed by Godsay, M. P. ;Harpell, G. A. ;Russell, K. E.
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The effect of a variety of phenols on the rate and degree of polymerization of styrene has been studied. With 1‐naphthol it is found that polystyryl radicals abstract the phenolic hydrogen atom, since 1‐naphthol has a far greater effect on the rate and degree of polymerization than 1‐deuteroxynaphthalene. Many phenols do not significantly retard the polymerization of styrene and transfer constants ranging up to 7.7 × 10^−3^ have been estimated for them. Other phenols, such as 1‐naphthol, 4‐methoxyphenol and 2,6‐diisopropylphenol, significantly decrease the rate and degree of polymerization. Transfer constants for these retarders have been calculated, both from the rate data alone by means of the treatment of Jenkins and from molecular weight data. The estimated values depend on the assumptions made concerning the mode of disappearance of the retarder radicals produced in the transfer reaction. Most of the retarders investigated give transfer constants in the range 10^−2^ to 10^−1^ but catechol, tert‐butylcatechol, and pyrogallol give larger values. An increased rate of polymerization observed in mixtures of styrene and some phenols is probably due to a higher rate of production of radicals by the initiator, azobisisobutyronitrile.
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