AbstractThe North Carolina atmospheric plasma system (NCAPS) was interfaced with electric diagnostics and computer‐based instrument control hardware and software to display plasma parameters in real‐time. The monitoring system is also interfaced with gas flow controllers and a Teflon‐coated thermocouple for continuous monitoring of the gas flow and the ambient temperature inside the plasma test cell. A simplified plasma model was developed and built in the interface system to solve for the plasma electron number density and display the results during device operation. Polyethylene terephthalate (PET) films were treated in the device using various gas combinations. The ambient gas temperature inside the test cell increases from 83 to close to 95°F (28.33–35°C) for most gases within 30 s, and further increases to about 105 (40.6°C) after 300 s of operation, indicating a nonthermal plasma condition inside the test cell. The interface solver shows that the electron number density decreases when PET films are immersed in the plasma, indicating recombination of etched species to the free electrons. Contact angle measurements showed that the wettability of PET surfaces increased after plasma exposure for all used gas combinations. Measurements of Young's modulus with dynamic mechanical analysis (DMA) showed an increase of the modulus of PET after treatment with helium plasma, whereas the modulus slightly decreased after treatment with oxygen, tetrafluorocarbon and hexafluorocarbon gases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
