This Field Application Report shows an example of each of these three general degradation processes. The analytical system consisted of a PerkinElmer Clarus 500 GC/MS interfaced with a CDS Analytical Pyroprobe 2500 Pyrolysis Autosampler*. Samples are rapidly pyrolyzed, automatically introduced into the GC carrier stream and transferred to the GC column for analysis by GC/MS. The specific polymers used are polyethylene, poly methyl methacrylate and poly vinyl chloride (PVC).
Samples of approximately 100 μg were analyzed using the conditions listed in Table 1. Sample preparation consisted of simply placing the sample into a quartz tube, which was introduced into the Pyroprobe automatically. No solvent is used, so there is no need for a solvent delay. In fact, some of the compounds found in the earliest eluting peaks may be important diagnostic products for the identification of a particular polymer. The GC column, carrier gas parameters, split ratio and so on are used in the same way as for samples introduced by any other means.
Random scission polyethylene
The total ion chromatogram for the pyrolysis of polyethylene (the pyrogram) is shown in Figure 1. Polyethylene is a very high molecular weight hydrocarbon, and the fragments produced via pyrolysis are just pieces of the original molecule small enough to go through the GC. This produces a pattern of peaks for successively longer oligomers, which is common for polyolefins.2 For polyethylene, the pattern consists of triplets of peaks, as shown in the expanded chromatogram in Figure 2. These are all normal hydrocarbons, and as shown by the spectra in Figure 3, they are identified as the alkane, alkene and diene of increasing chain lengths. Other polyolefins, such as polypropylene, polybutylene and so on, behave in the