A study of curative interactions in cis-1,4-polyisoprene. IX. The role of ZnO in thiuram-based vulcanization systems
| Autor: | F. W. H. Kruger, W. J. McGill |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Reaction mechanism
Polymers and Plastics Vulcanization chemistry.chemical_element General Chemistry Zinc Tetramethylthiuram disulfide Sulfur Surfaces Coatings and Films law.invention Dimethyldithiocarbamate chemistry.chemical_compound chemistry law Polymer chemistry Materials Chemistry Molecule Curing (chemistry) |
| Zdroj: | Journal of Applied Polymer Science. 45:749-753 |
| ISSN: | 1097-4628 0021-8995 |
| DOI: | 10.1002/app.1992.070450501 |
| Popis: | During the vulcanization of cis-1,4-polyisoprene (IR) with thiruam-related curing systems, dimethyldithiocarbamic acid (DMDCA) is formed as a byproduct, in the formation of either pendent groups or crosslinks. DMDCA is unstable, and decomposes instantly to Me2NH and CS2 in the absence of ZnO. The facile reaction of Me2NH and thiuram-related molecules such as tetramethylthiuram polysulfides, tetramethylthiuram disulfide (TMTD), tetramethylthiuram monosulfide and pendent groups caused (i) increased induction periods, (ii) lower maximum crosslink densities, and (iii) the excessive formation of tetramethylthiourea (TMTU). A most important function of ZnO was to trap the DMDCA via the formation of zinc dimethyldithiocarbamate and water, thereby preventing the detrimental reactions above. The IR/TMTD/ZnO and IR/sulfur/TMTD/ZnO systems were therefore characterized by (i) shorter induction periods, (ii) higher maximum crosslink densities, and (iii) the absence of TMTU. |
| Databáze: | OpenAIRE |
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