Identification of Organic Compounding Ingredients in Vulcanized Rubbers by Thin Layer Chromatography

Abstract

As a result of a search for a method for the simultaneous analysis of organic compounding ingredients in vulcanized rubber by one dimensional and two dimensional thin layer chromatography, a method was discovered by which it was possible to identify directly 24 accelerators and 19 antioxidants. The sample was developed on a Wakogel B-5 (silica gel) plate with chloroform/benzene (10/9) in one direction and then with ethanol in the other direction. The plate was sprayed with formalin/sulfuric acid (1/4) and then heated for one hour at 120° C. It was found that the 43 compounding ingredients could all be identified from their Rƒ values and the colors of the spots. Good results were also obtained in the actual analysis of the organic compounding ingredients in vulcanized rubbers. Investigation of interference by the base rubbers showed that the organic compounding ingredients could be identified. Translator's note: According to the English summary, the silica gel contains 5% of calcined gypsum. This is not mentioned in the Japanese text.

Rubber

“…There were several papers on thin layer chromatography for separation of curing agents extracted from rubber. Both the Rt values and the colors developed by sprays are helpful in the identification (116,152).…”

“…In the case of sulfenamides, detection of the amine can help to make the proper identification. Two-dimensional chromatography is a more powerful separating tool (152). Thiuram disulfides and dithiocarbamates were detected by spraying thin layer chromatograms with 3% CuS04 solution (190).…”

“…Identification. Some of the thin layer chromatography methods applied to curing agents also include age resisters within their scope (58,116,152). More positive identification of M-phenyl-2naphthylamine and Ar-pheny 1-Ar'-2-propyl-p-phenylenediamine is made by supplementing thin layer chromatography with their characteristic ultraviolet spectra (216).…”