Zinc-complexes in natural rubber latex sulphur vulcanisation system
2009
Siti Nor Qamarina M. | Amir Hashim M. Y.
Zinc-complexes are essential ingredients in natural rubber latex (NRL) sulphur vulcanisation systems as they enhance the vulcanisation efficiency and improve the vulcanisate properties. Sulphur, zinc-type accelerators and zinc oxide (ZnO) are the main chemical ingredients utilised in a vulcanisation system. Zinc type accelerators accelerate the vulcanisation process in many rubber products manufacturing, while ZnO, enhances the vulcanisation efficiency. However, these chemicals may form residuals and could be released from the vulcanisates, either during the product manufacturing process or from the finished products. These chemicals may contribute towards environmental pollution, while some residuals are known to induce Type IV skin sensitivity. Thus, understanding the role of these zinc-containing chemicals in the processing of NRL based products can help the optimisation on the amount of chemicals needed for the latex products. This study showed that the amount of residual carbamate (DEC) extracted from vulcanised NRL films reduced with increased amount of ZnO content. The physical properties and crosslink densities of NRL films improved with addition of zinc diethyl dithiocarbamate (ZDEC) and ZnO. The study also confirmed the effect of heating whereby NRL films heated at high temperature demonstrated prominent differences in physical properties and residual DEC.
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