AbstractThe oxidative effect of fuming nitric acid upon finely ground polyethylenes is observed by plotting changes in specific solution viscosity values against duration of reaction. The similarity in relationship between this reaction and that of polyethylenes with oxygen is set forth. It is shown that this reaction, like that between polyethylenes and oxygen gas, produces hydroperoxide and carbonyl structures, and results largely in scission of the polymeric chains. The effect of these oxidative alterations in decreasing the electrical resistivity and in increasing the flow properties of the subject resins is illustrated. The identical influence of methyl branching in favoring the reaction of polyethylenes with both oxygen and with fuming nitric acid is demonstrated. Nitration is seen to be a consequence of extent of reaction rather than of reaction temperature itself. The utility of this reaction in differentiating among polyethylenes is indicated. In this regard it is seen that the linear polymers are more severely affected by fuming nitric acid than are conventional polyethylenes. Finally, the usefulness of this reaction in assessing the inherent oxidizability of polyethylene resins, independent of the presence or absence of antioxidants, is proposed.
展开▼
