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Sequence distributions of triads in the molecular chains of vinylidene chloride/vinyl chloride copolymers were investigated by means of pyrolysis-gas chromatography. The experimentally determined concentrations of triads are quantitatively in agreement with those calculated from the copolymerization theory. The presented example by pyrolysis-gas chromatography suggests that this method becomes fairly applicable to the explanation of the molecular structure of copolymers by improvement of the experimental technique. ZUSAMMENFASSUNG :Die Sequenzverteilung von Triaden in den Molekelketten von Vinylidenchlorid/Vinylchlorid-Copolymeren wurde mit Hilfe der Pyrolyse-Gaschromatographie untersucht. Die experimentell ermittelten Konzentrationen von Triaden stimmen quantitativ iiberein mit denjenigen Konzentrationen, welche nach der Theorie der Copolymerisation berechnet wurden. Die dargestellten Beispiele der Pyrolyse-Gaschromatographie zeigen, daB diese Methode bei Verbesserung der experimentellen Technik anwendbar und zur Deutung der molekularen Struktur von Copolymeren geeignet ist.

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Ethylene-propylene-diene rubbers (EPDMs) are now used for various purposes because of their excellent resistance to ozone, weather, and heat. Therefore, many kinds of EPDMs are provided as commercial polymers. Consequently, reliable methods for the structural characterization of EPDM have been needed in the fields of material development, process control, and quality assurance of the cured products. The iodine value method is generally used to determine the diene content in EPDMs. However, it is too time consuming to be a routine method. Until now, spectroscopic methods such as IR and NMR are generally used for the study of the composition and the sequence length distributions in EPDMs. Levine and Haines determined the content of ethylidenenorbornene (ENB) in ethylene-propylene-ethylidenenorbornene rubbers (ENB-EPDMs) by IR. Florence and Loustalot investigated ethylene-propylene-1.4-hexadiene rubbers by NMR. However, these spectroscopic methods often encountered the difficulties in the analysis of vulcanized rubbers since they were insoluble and usually contained many kinds of additives such as curing agents, plasticizers, stabilizers, and fillers. On the other hand, owing to the recent development of excellent pyrolyzers and highly efficient fused-silica capillary columns, pyrolysis-gas chromatography (PyGC) has become a powerful tool to give unique information about structures of high polymers. Furthermore, PyGC is advantageous to the practical analysis of insoluble polymeric materials such as vulcanized rubbers.

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