Analysis of the linear methods for determining copolymerization reactivity ratios, VII. A critical reexamination of radical copolymerizations of styrene

The reactivity ratios of 8000 published styrene copolymerization systems have been reviewed in terms of the extended Kelen‐Tüdős method. Only 649 systems were described in sufficient detail for reevaluation and classification. r‐Values, together with their 95% confidence limits have been calculated. Quantities δ□ and Q, suitable for classification of the systems, have been applied. Of the 649 reevaluated systems, 243 (37.5%) were found to belong to class I and 221 (34.1%) to class I(!), i.e. 464 (71.6%) systems for which the conventional copolymerization equation was found to be adequate. 66 (10.2%) class II systems were found where the two‐parameter model does not hold. Finally, 118 (18.2%) systems were judged to belong to class III, i.e. systems for which the experimental data are inconsistent and the published r‐values meaningless.