The Contribution of Integrated Pyrolysis/Gas Chromatography to the Elucidation of Polymer Microstructure

Abstract

Although pyrolysis/gas chromatography is now an established technique for the qualitative examination of high polymers, its potential as a quantitative method of analysis has never been widely recognised. It has been shown that simpler chromatograms are obtained by working with samples of about 1 microgramme. This simplification is not because of a lack of sensitivity in the detection system, but because of elimination of secondary reactions which invariably occur during the migration of primary degradation fragments through a hot polymer mass. Naturally, simpler chromatograms are easier to interpret, and this has led to an examination of the technique from the point of view of quantitivity. Initially, it is convenient to restrict observations to polymers which are capable of yielding the parent monomers by the process of thermal depolymerisation. Six model copolymers of stryrene and methyl methacrylate are shown to behave in a predictable manner on this scale of operation, and there is every reason to accept the method as a standard quantitative procedure provided that certain elementary precautions be taken. Having established a technique for reproducible quantitative pyrolysis, it has become possible to study the microstructure of some homopolymers and simple copolymers, in particular where the copolymer contains species which as homopolymers show the opposing behaviour of depolymerisation and random fission.