Evolved gas monitoring from PA66 by using PY-GC-HRTOFMS
Compounds which are generated upon heating polymer materials include monomers, additives and fragments characteristic of the polymer materials. Low molecular weight compounds generated by pyrolysis and/or locally desorption are observed. The relationship between the behavior of evolved gas compounds and the heating temperature is important for understanding the chemical characteristics of polymer materials. A gas chromatograph (GC) - mass spectrometer (MS) with thermogravimetric / differential thermal analyzer (TG/DTA) or pyrolyzer (Py) is generally used to identify the thermally evolved gas compounds from polymer materials. However, GC with a low-resolution MS such as quadrupole MS (QMS) may have difficulty monitoring low molecular-weight compounds generated by heating, since the GC is not used to provide chromatographic separation and QMS has poor mass spectrometric separation in the low mass region. (For example, N2+·, CO+· and C2H4+· are detected as the same signal of nominal mass m/z 28.)
We report the use of Py - GC - high resolution time-of-flight MS (HRTOFMS) for monitoring the low-molecular weight compounds generated upon heating the polymer materials. This report focuses on the generation of low molecular weight compounds near m/z 18, 28, and 4.
A small piece of commercial PA66 (Nylon 66) 0.28mg was measured without further sample preparation by using PY/GC/HRTOFMS, using the JMS-T200GC "AccuTOF GCx-plus” coupled with a PY-2020iD. Measurement conditions were shown in Table 1. To detect evolved gases by heating, we used a low filament current.