Sulfidation promoting mechanism of zinc dithiocarbamate
Because of the shortcomings of traditional methods, people are constantly exploring new research methods. People use the model compound (MCV) method (the model compound refers to the molecular structure similar to the real rubber molecule, but the size is small.), The crosslinking precursor was observed by means of HPLC (high performance liquid chromatograph) and the sulfur crosslinking model formed subsequently was speculated. However, since various hardening reactions of MCV occur simultaneously, it is difficult to observe the reaction pathways followed by individual components.

In order to overcome this problem, in the mid-1990s, Nieuwenhuizen research group of Leiden University developed a new method, that is, under the condition of simulating the vulcanization process, to study the sulfur-containing cross-linked low molecular weight model compounds and their precursors, so as to understand the changing chemical pathways and the catalytic effect of the complexes. Using this method, combined with quantum chemical calculations, they revealed a large number of homogeneous catalytic reactions of zinc dithiocarbamate (zdmc) and zinc dimercaptobenzothiazole salt (zmbt) during vulcanization, including the formation, desulfurization, degradation and sulfur crosslinking reactions of precursors.

The uniqueness of its research lies in:
(1) By using quantum chemical calculation and matrix assisted laser desorption ionization mass spectrometer, the existence of intermediate of zinc dithiocarbamate sulfur rich complex was confirmed theoretically and experimentally for the first time. Using matrix assisted laser desorption ionization mass spectrometer, the isolated complex was treated in vacuum (to prevent the conversion or loss of S atoms). The results showed that the polysulfide complex could be enriched to four S atoms.
(2) Under the simulated vulcanization conditions, the vulcanization promoting mechanism of zinc dithiocarbamate and zinc thiazole salt was revealed.