Fractionation of Rubber by Column Absorption Chromatography. and Its Chemical Composition

Abstract

As an application of fractionation of copolymers by means of thin layer chromatography (TLC), the experiment on the column absorption chromatograph of copolymers was undertaken and the accompanying problems have been studied. The samples used were styrene butadiene copolymer (SBR) with carious molecular weight and styrene content. Mixtures of various solvents were tested on TLC plate to find relevant developer for TLC ans found that the mixture of cyclohexane and benzene was suitable. Typical chromatograms are shown in Fig.2. Molecular weight of the samples was found to be independent of an Rf value. Absorption and desorption experiment of the samples onto silica gel in the developer was also performed to find the loss of weight of the desorbed material. Approximately 70% og weight recovery was observed. The molecular weight distribution and the styrene content of the recoverd fractions were compared with those of the original material. On the basis of the fact that no difference was found between those values, the composition of the sample can be deduced from the analy-sis of the recovered fractions. An idea of multilayer absorpotion or desorption mechanism was proposed to understand the experimental result. Samples were then subjected to cplumn ab-sorption chromatography under the same condition as TLC described above. In this case, samples were prepared by mixing two fractions with different styrene content in the end fractions were observed as expected. Analytical result of styrene content in fractions was normal just before the reversal occurred. Two different SBR, polymerized in emulsion or in solution were choromatographed by this method and the respevtive composition distribution curves were ob-tained. For the former the shape of distribution cureve was broad while for the later it was sharp.