The Interaction of Tetramethylthiuram Disulfide with Rubber and with Compounds Containing a Labile Hydrogen Atom

Abstract

Abstract In the interaction of TMTD with rubber, sulfur and nitrogen from the TMTD add to the rubber, a maximum being exhibited on the rate curve for sulfur addition. At the same time dimethyldithiocarbamic acid is formed which, in mixtures containing zinc oxide, becomes bound in the form of Zn-DDC but which decomposes to carbon disulfide and dimethylamine in mixtures containing magnesium and calcium oxides and in the absence of metallic oxides. In the absence of oxides or in the presence of CaO or MgO a less dense three dimensional network is formed and reversion takes place which is accelerated by carbon disulfide and dimethylamine. The degree of crosslinking increases with increase in content of 1,4 structural units while the amount of combined sulfur and the rate of accumulation of zinc dithiocarbamate diminish. Dithiocarbamic acid also forms in the interaction of TMTD with geraniol and isopropylbenzene. The thermal decomposition of TMTD to thiuram monosulfide, sulfur, tetramethylthiourea and carbon disulfide takes place in the absence of compounds with a labile hydrogen atom. The reaction proceeds through the stage of rupture of the S—S and C—;S bonds of TMTD to form free radicals. The radical mechanism of the reaction is confirmed by electronic paramagnetic resonance specta.