The work reported here is consistent with, but not conclusive proof for, the coupling theory of eddy diffusion. The proof of this theory would be greatly advanced if it were possible to show the actual variation of A with flow velocity. This would be enormously difficult using the ordinary gas chromatographic methods. Glueckauf (17) has shown this kind of variation in a liquid system but it is difficult to judge the reliability of his data. The fact that the classical eddy diffusion picture seems to work in chemical engineering studies, many in the proper range of Reynolds numbers, indicates that the predicted transistion with velocity occurs at some point. The authors are not familiar with any experimental work which is in significant disagreement with the coupling theory.

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A technique combining thermogravimetry (TG) and gas chromatography (GC) is described, which follows the weight changes of a sample as it is heated under controlled conditions, collects the volatiles at various stages as shown on the TG curve, and then analyzes them intermittently by GC. The technique features precise control of temperature and atmosphere and use of minimum thermal energy to perform pyrolysis, therefore reducing the production of secondary products and providing simple and reproducible GC scans. Impurities, such as solvents, monomers, additives, etc., can be analyzed separately from the polymers. Both qualitative and quantitative information on the various components in the sample can be obtained? In favorable cases, polymer blends and microstructures can be studied. Pyrolysis-gas chromatography (GC) has been establishedas a technique for characterization of high polymers (1-3).Pyrolysis of the sample is usually carried out either on a hot wire or ribbon inside the injection port, or in an oven-type unit from which the pyrolysis products can be produced and then injected into the gas chromatograph. The advantages and disadvantages of each method have been extensivelydiscussed by various authors (4-10). Thermogravimetry (TG) is a well known technique for following changes in mass of a material as a function of temperature. Its applications to high polymers have included the study of thermal stability, analysis of additives, and characterization of polymer blends and copolymers (11). The possibility of coupling the two powerful techniques, thermogravimetry and gas chromatography, has been reported (12,13). However, no experimental results have been given in the literature. This presentation describes a combined TG-GC technique which follows the weight changes of a sample as it is heated under controlled conditions, collects the volatiles at various stages as indicated on the TG curve, and then analyzes them intermittently by GC. In a way, this approach is similar to the oven-pyrolysis GC method, except that the extent of pyrolysis is now guided and measured quantitatively by the (1) B.

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