Separation and identification of various vulcanization agents and antioxidants in two types of rubber by chromatographic and spectrometric methods.
The aim of this study was to separate and identify by chromatographic and spectrometric methods, the various allergenic vulcanization agents and antioxidants used in the manufacture of industrial rubber. Specimens of elastomers were manufactured specially for this study. The specificity of the gas chromatographic method developed allows separation of all the manufacturing additives in the selected rubber types after one injection only, even though they belong to extremely varied chemical categories. The GLC method was coupled with mass spectrometry, which permitted identification of the peaks obtained and the study of the fragmentation of the 4 reference products under various conditions. Separation by TLC was performed in parallel on the same extracts, allowing rapid identification of the products tested for, and showed new spots after vulcanization.
Vulcanization. Part I. Fate of Curing System during the Sulfur Vulcanization of Natural Rubber Accelerated by Benzothiazole Derivatives
Abstract Several investigators have proposed mechanisms for the delayed action sulfur vulcanization of rubbers which postulate that a number of intermediate compounds containing fragments of the accelerator are formed during the vulcanization cycle. Although a number of workers have measured the change in initial accelerator and sulfur concentration in the rubber during vulcanization, none have identified and determined the intermediate compounds which appear to be formed during vulcanization. The purpose of this paper is to first confirm the existence of these intermediates and subsequently to identify and quantitatively follow their concentrations throughout the vulcanization cycle. In our initial studies we have limited our investigations to natural rubber cured with sulfur and accelerated with (i) MBT (2-mercaptobenzothiazole), (ii) (MBTS)[2,2′-dithiobisbenzothiazole)], and (iii) 2-(4-morpholinothio)benzothiazole. In order to reduce the complexity of the system, other normally used additional curing a...
Thin-layer chromatographic determination of antioxidants by the stable free radical α, α′-diphenyl-β-picrylhydrazyl
The reaction between the stable free radical α,α′-diphenyl-β-picrylhydrazyl (DPPH) and antioxidants can be used for the visualization of antioxidants in thin-layer chromatography. Amounts of tocopherols down to 0.5 μg can be detected. The identification of tocopherols in oils and other natural products and of synthetic antioxidants, added to lard, are described. Saponification is not required. Quantitative analyses of γ-tocopherol give satisfactory results.