Instrument: 7000 Headspace Autosampler
Evaluation of Styrene-Butadiene Polymers Using High Temperature Static Headspace Gas Chromatography
Polymers are used in a wide variety of consumer products. It is highly desirable to have simple quality control methods for determining the levels of residual monomers as well as to qualitatively assess other off-gassed volatile components. The analysis of volatile components in polymers is challenging, however, because they are often bound or trapped within the sample matrix.
The volatile components in styrene-butadiene rubbers are often evaluated by first dissolving the polymer in a suitable solvent, such as dimethylformamide (DMF). An aliquot of the solution is then added to a headspace vial for subsequent analysis. But solvent extraction is a time-consuming process and the upper temperature limit of the headspace analyzer must be maintained below the boiling point of the solvent. One of the consequences of this limitation is that no process information can be gleaned from the data.
At temperatures approaching, and exceeding, the glass transition temperature of a polymer, there is increased flow with movement of analytes throughout the matrix. For many polymers, however, the glass transition temperature is above 250°C. Under these higher temperature conditions, a polymer begins to “unzip”, yielding useful process information. Because polymers are synthesized differently, high temperature headspace gas chromatography analysis can provide unique fingerprint chromatograms for each specific type of polymer. This information will be helpful to the analyst in determining the source and other aspects of the material. In this paper, styrene-butadiene rubber samples are evaluated under high temperature headspace conditions to generate fingerprint chromatograms.
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