The Reactivity of Phenols toward Peroxy Radicals. I. Inhibition of the Oxidation and Polymerization of Methyl Methacrylate by Phenols in the Presence of Air

Abstract

+ X 0 + A I , is given by an expression of the type ES and if the equilibrium constant is given by an expression of the form (which is approximately true), then the recombination constant will be given bywith a similar expression for kg. The factor *1 is about the same for the two reactions. From a simple viewpoint the PZ factors would also be about equal. \$'ith s = 3 the ratio of the (En/ Rl')s-l terms contributes a factor of about 9 to ks k2. The rest of the difference in the rates of the 0 + NO + M and 0 + Os + 11 reactions remains unexplained.Acknowledgments.-The support of this work by the Office of Naval Research is gratefully acknowledged. Lye thank Professor S. W. Benson arid Dr. 0. K. \ITulf for helpful discussions and Professor R. 11. Badger for the loan of the spectrograph. Lye are much indebted to Dr. R. E. Duff for making his computing codes available to us LT. 11. Jones expresses his appreciation to the In an effort to elucidate the mechanism by which phenols retard vinyl polymerization in the presence of air, the action of twenty phenols upon the polymerization of methyl methacrylate has been studied Induction periods and rates of polymerization have been measured dilatornetrically. .kddition of a phenol increases the length of the inhibition period iuvcr that due to oxygen alone. A % kinetic scheme has becn developed which accords well with the cxperirnental results. On this basis it is concluded that phenols act as anti-oxidants, as is often found to be the case in other free-radical reactions. The phenol prevents oxygen from becoming depleted too rapidly, thus extending the inhibition period by niaintaining a reasonably high os>-gen concentration level for a longer time than would normally be the case. Relative eficiencies of several phenols have been determined and these results correlated with other kinetic studies of oxidation inhibition by phenols.

The Inhibited Autoxidation of Styrene: Part Ii. The Relative Inhibiting Efficiencies of Meta- And Para-Substituted Phenols

“…Reaction [7] may possibly be an example of this phenomenon. Similarly, the fact that reaction [15] definitely follows u+ constants whereas reactions [13] and [14] tend more to favor a constants would also be in line with this suggestion.…”

“…With the exception of reaction [2], compounds containing one or two ortho substituents have not been included in the determination of p. The original data have been recalculated in most cases* and the best correlation, i.e., that giving the smallest standard deviation (root mean square in loglo units), is given in heavy type. I t can be seen that in aromatic solvents and in CC14 only reactions [7] and [14] are better represented by u than by a+ and that for reactions [4] and [13] no distinction can properly be made.…”

Composites - Characterization of Composite Filling Materials: Reactor Response

“…The reactivity of oxygen to a radical is much higher than that of a monomer (Schulz and Henrici, 1956;Ruyter, 1980;Ruyter, 1981). The length of the inhibition period is proportional to the initial concentration of oxygen, and the added inhibitor (Caldwell and Ihrig, 1962;Asmussen, 1982b). The concentration of dissolved molecular oxygen in liquid methacrylate monomers is about 60 ppm (Ruyter, 1980).…”

An approach to imprint irganox 1076: Potential application to the specific migration test in olive oil

“…The experimental conditions to prepare the polymers are shown in Table II. Degasification with N 2 showed to be an important parameter to control through the experimental study because of the simultaneous presence of the phenolic compound and oxygen that could inhibit the polymerization 20…”