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A nonthermal, pulsed spark discharge is applied to three polymer powders in Ar and Ar–H2 ${{\rm{H}}}_{2}$ gas mixtures. Hydrogen is introduced to assess plasma‐driven decomposition. Gaseous decomposition products, including methane, acetylene, and ethylene, are observed with Fourier‐transform infrared (FTIR). Surface modifications are observed on the residual polymer via attenuated total internal reflection‐FTIR. Time‐averaged rotational, vibrational, and excitation temperatures are characterized in the discharge. The plasma density is found to be around 3×1022 m−3 $3\times 1{0}^{22}\unicode{x0200A}{{\rm{m}}}^{-3}$, with rotational and vibrational temperatures ranging from 1500 to 2200 K and an excitation temperature of 1–2 eV. While spark properties did not change with either gas composition or polymer composition, it was determined that the addition of hydrogen promoted higher concentrations of gaseous phase products (promoting hydrogenolysis). [ABSTRACT FROM AUTHOR]

Outside Front Cover: A spark discharge in an argon and argon–hydrogen mixture provides evidence of plastic depolymerization of low‐density polyethylene, polypropylene, and polyethylene terephthalate. Light hydrocarbon products and the resulting polymer surface are analyzed and connected to the discharge properties.For further information see the article by Roxanne Z. Walker, Sophia Gershman, Dorothy E. Doughty, and John E. Foster (e2300155).By Roxanne Z. Walker; Sophia Gershman; Dorothy E. Doughty and John E. FosterReported by Author; Author; Author; Author [Extracted from the article]