Electron Spin Resonance Study of the Interaction of Tetramethylthiuram Disulphide (TMTD) with Rubber and Related Compounds

In the article by Dogadkin and Shershnev electron paramagnetic resonance spectra produced in the laboratory of Prof. S. E. Bresler are put forward to confirm the radical mechanism of the interaction of TMTD with raw rubber in the process of vulcanization. After this paper had been printed we learned of the work of B. R. McGarvey and H. M. McConnel, in which analogous spectra were observed in solutions containing bivalent copper ions. As a result it is suggested that the electron paramagnetic resonance spectra of stocks of natural rubber with TMTD are affected by admixtures of copper compounds. The amount of copper calculated from the magnitude of the resonance spectrum amounts to 0.1% by weight in relation to the TMTD. The same spectrum is observed on heating a benzene solution of copper acetate and TMTD. Its intensity increases sharply and irreversibly on heating the solution to 100°. corresponding to 10% of the copper contained in the solution.