Determination of the temperature—time profile of the sample in pyrolysis—gas chromatography

The mean temperature-time profile in a sample has been determined in order to establish whether it is possible to equate the temperature of the pyrolyzer with that of the sample being pyrolyzed. This was done by studying the degradation of cis-1,4-polybutadiene be sequential pyrolysis. The rate of degradation was determined for different amounts (0.5–20 μg) of sample. The temperature dependence of the degradation rate was determined from an Arrhenius plot. The experimental results were combined with theoretically derived expressions for the heating of samples subjected to pyrolysis. The temperature–time profiles of different amounts of sample could then be calculated.It was found that samples thinner than 1 μm were heated to a mean temperature of 95% of the temperature of the pyrolyzer in 40 ms or faster. Too thin samples can give rise to noticeable catalytic effects.By choosing the appropriate pyrolysis conditions of sample thickness, time and temperature it is possible to assume that the temperature of the sample is nearly the same as that of the pyrolyzer.