Determining the Outgassing Kinetics of a Cryo-Milled Polymer Using Temperature-Programmed Desorption SIFT-MS

We perform temperature-programmed desorption (TPD) directly on cryo-milled polymeric samples with selected ion flow tube mass spectrometry, SIFT-MS, to measure outgassing kinetics and the onset of thermal decomposition. Specifically, we monitored siloxane outgassing from the silicone elastomer encapsulant Sylgard 184. The TPD spectra reveal a rich and complex VOC emission landscape up to the point of thermal decomposition. We performed experiments at multiple ramp rates and successfully applied Kissinger analysis to all observed emission peaks, which indicated activation energies in the range of 30–55 kJ/mol and exponential prefactors of 10²–10⁵ s^–1. Finally, we relate reagent ion depletion in the SIFT-MS and total mass loss from thermogravimetric analysis (TGA) and find that the two techniques agree well on the onset of thermal decomposition, which was found to be approximately 250 °C. This novel application of TPD-SIFT-MS to obtain emission kinetics could prove useful in indoor air quality studies, where understanding the rate of VOC emission is crucial for model development.