Abstract
In order to elucidate the mechanism of generation of free radicals from the sodium formaldehyde sulfoxylate (I)—iron—hydroperoxide system, the reactions between (I) and Fe3+ and between (I) and Fe3+-EDTA were studied in both acidic and alkaline media. The second-order rate constant (k2) for the former at pH 4 was 76.0 M−1 sec−1, and for the latter 0.00294 M−1 sec−1 (pH 4) and 0.447 M−1 sec−1 (pH 9) at 18°C. The reactions of Na2S2O4—Fe3+ and Na2S2O4—Fe3+-EDTA were very rapid, and their rates were only roughly estimated. The mechanisms of generation of free radicals in the (I)—Fe3+—ROOH system and the Na2S2O4—Fe3+—ROOH system were discussed on the basis of the data obtained.
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If the free radicals produced are not wasted by reactions other than that with monomers, the rate of polymerization is determined by the rate of production of free radicals. If the polymerization is to be completed within a reasonable length of time (for instance, 2—20 hr), the desirable half-life of an initiator is approximately 1–10 hr.
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Minato, H., Iwakawa, M. Generation of Free Radicals at Subzero Temperatures. IV.1 On the Mechanism of Generation of Free Radicals from the Sodium Formaldehyde Sulfoxylate—Iron—Hydroperoxide System. Polym J 6, 234–237 (1974). https://doi.org/10.1295/polymj.6.234
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DOI: https://doi.org/10.1295/polymj.6.234