@article{matthews_hwang_mccord_bourham_2004, title={Investigation into etching mechanism of polyethylene terephthalate (PET) films treated in helium and oxygenated-helium atmospheric plasmas}, volume={94}, ISSN={["1097-4628"]}, DOI={10.1002/app.21162}, abstractNote={This research makes an investigation into the etching mechanism of atmospheric plasma conditions on the surface of polyethylene terephthalate (PET) films. Two types of untreated PET films (S/200 and S/500) were exposed to plasma for 0 to 5.0 min in 30-s increments. The first set of each film type was treated in helium plasma, while the second was treated in oxygenated-helium plasma. Differential Scanning Calorimetry (DSC) was used to characterize pre- and post-exposure films. Weight changes and the degree of solubility were also determined. Based on peak area results, the percent crystallinity of PET S/200 increased by an average of 4.57% (helium treated) and 13.56% (oxygenated-helium treated), while the S/500 showed only a small increase. There was no significant change in the melting or crystallization temperatures of either film type, indicating a decrease in amorphous content versus an increase in crystalline material. Weight loss analysis supports this theory. Solubility testing revealed a continual decrease in swelling as exposure time was increased. A model was developed to predict the change in the degree of solubility for polyphase surfaces considering the etching rate per phase. The model was applied to PET with good correlation between the model and experimental data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2383–2389, 2004}, number={6}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Matthews, SR and Hwang, YJ and McCord, MG and Bourham, MA}, year={2004}, month={Dec}, pages={2383–2389} }
 @article{hwang_matthews_mccord_bourham_2004, title={Surface modification of organic polymer films treated in atmospheric plasmas}, volume={151}, ISSN={["1945-7111"]}, DOI={10.1149/1.1756891}, abstractNote={The effect of plasma treatment on surface characteristics of polyethylene terephthalate films was investigated using helium and oxygenated-helium atmospheric plasmas. Sample exposure to plasma was conducted in a closed ventilation test cell inside the main plasma chamber with variable exposure times. The percent weigh loss of the samples showed an initial increase followed by decrease with extended exposure time, indicating a combined mechanism of etching and redeposition. The wettability as measured by the contact angle showed a sharp initial increase followed by a steady-state trend with increased exposure time, suggesting a change in surface functionality. Atomic force microscopy analysis revealed increase in surface roughness, as well as evidence of redeposition of etched volatiles. Functionality changes were measured using X-ray photoelectron spectroscopy and these changes were correlated to the new plasma-induced properties.}, number={7}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Hwang, YJ and Matthews, S and McCord, M and Bourham, M}, year={2004}, pages={C495–C501} }
 @article{cai_qiu_zhang_hwang_mccord_2003, title={Effect of atmospheric plasma treatment on desizing of PVA on cotton}, volume={73}, DOI={10.1177/004051750307300803}, abstractNote={Both air/He and air/O 2/He atmospheric plasma treatments are applied to desize PVA on cotton, then PDR (percent desizing ratio) and tensile strengths of cotton fabrics and single yams are measured. XPS and SEM are used to analyze the effects of atmospheric pressure plasma treatments on PVA. These treatments can both remove some PVA sizing and significantly improve PDR by washing, especially by cold water washing. The tensile strengths of cotton fabrics treated with atmospheric pressure plasma are the same as for the unsized fabric. XPS analysis of the plasma treated PVA films reveals surface chemical changes such as chain scission and formation of polar groups, which promote the solubility of PVA in cold water. Air/O2/He plasma is more effective than air/He plasma on PVA desizing.}, number={8}, journal={Textile Research Journal}, author={Cai, Z. S. and Qiu, Y. P. and Zhang, C. Y. and Hwang, Y. J. and McCord, Marian}, year={2003}, pages={670–674} }
 @article{hwang_qiu_zhang_jarrard_stedeford_tsai_park_mccord_2003, title={Effects of atmospheric pressure helium/air plasma treatment on adhesion and mechanical properties of aramid fibers}, volume={17}, ISSN={["0169-4243"]}, DOI={10.1163/156856103321645194}, abstractNote={In order to investigate the effect of atmospheric pressure plasmas on adhesion between aramid fibers and epoxy, aramid fibers were treated with atmospheric pressure helium/air for 15, 30 and 60 s on a capacitively-coupled device at a frequency of 5.0 kHz and He outlet pressure of 3.43 kPa. SEM analysis at 10 000× magnification showed no significant surface morphological change resulted from the plasma treatments. XPS analysis showed a decrease in carbon content and an increase in oxygen content. Deconvolution analysis of C1s, N1s and O1s peaks showed an increase in surface hydroxyl groups that can interact with epoxy resin. The microbond test showed that the plasma treatment for 60 s increased interfacial shear strength by 109% over that of the control (untreated). The atmospheric pressure plasma increased single fiber tensile strength by 16-26%.}, number={6}, journal={JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY}, author={Hwang, YJ and Qiu, Y and Zhang, C and Jarrard, B and Stedeford, R and Tsai, J and Park, YC and McCord, M}, year={2003}, pages={847–860} }
 @article{mccord_hwang_qiu_hughes_bourham_2003, title={Surface analysis of cotton fabrics fluorinated in radio-frequency plasma}, volume={88}, ISSN={["0021-8995"]}, DOI={10.1002/app.11896}, abstractNote={Cotton fabrics were treated by radio-frequency plasma with tetrafluoromethane (CF4) and hexafluoropropene (C3F6) gases under different exposure times, pressures, and power levels. The hydrophobicity and water repellency were analyzed with measurements of the cosine of the contact angle (cos θ) and wet-out time. The hydrophobicity was enhanced with treatments of both gases. X-ray photoelectron spectroscopy (XPS) revealed increases in the surface fluorine content of 1–2% for CF4 plasma and of 2.3–7.8% for C3F6 plasma. The relative chemical composition of the C1s spectra after CF4 and C3F6 plasma treatments showed increases in the relative amounts of COC and fluorocarbon groups (CF, CF2, and CF3), whereas peak areas for COH and COOH decreased. The hydrophobicity was enhanced by the increase in the fluorine content and fluorocarbon groups. C3F6 plasma treatment resulted in higher hydrophobicity than CF4 plasma treatment according to not only cos θ and wet-out measurements but also XPS analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2038–2047, 2003}, number={8}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={McCord, MG and Hwang, YJ and Qiu, Y and Hughes, LK and Bourham, MA}, year={2003}, month={May}, pages={2038–2047} }
 @article{hwang_an_mccord_park_kang_2003, title={The effect of etching on low-stress mechanical properties of polypropylene fabrics under helium/oxygen atmospheric pressure plasma}, volume={4}, ISSN={["1229-9197"]}, DOI={10.1007/BF02908270}, number={4}, journal={FIBERS AND POLYMERS}, author={Hwang, YJ and An, JS and McCord, MG and Park, SW and Kang, BC}, year={2003}, month={Dec}, pages={145–150} }
 @article{qiu_hwang_zhang_bures_mccord_2002, title={Atmospheric pressure helium plus oxygen plasma treatment of ultrahigh modulus polyethylene fibers}, volume={16}, ISSN={["1568-5616"]}, DOI={10.1163/156856102760067217}, abstractNote={Ultrahigh modulus polyethylene fibers were treated with atmospheric pressure helium + oxygen plasma in a capacitively coupled device at a frequency of 7.5 kHz. The fibers were treated for 0, 0.5, 1, 1.5, and 2 min. The surfaces of the fibers treated with He + O2 plasma were etched and micro-cracks were formed. XPS analysis showed a 65ndash213% increase in oxygen content on the surfaces of all plasma-treated fibers, except for the 1.5 min group. An increase in the concentration of C—O and the appearance of C=O bonds on the surfaces of plasma-treated fibers were observed. In the micro-bond test, He + O2 plasma-treated groups had a 65–104% increase in interfacial shear strength over that of the control. The tensile strength of the fibers was either unchanged or decreased by 10–13% by the plasma treatments.}, number={4}, journal={JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY}, author={Qiu, Y and Hwang, YJ and Zhang, C and Bures, BL and McCord, M}, year={2002}, pages={449–457} }
 @article{mccord_hwang_hauser_qiu_cuomo_hankins_bourham_canup_2002, title={Modifying nylon and polypropylene fabrics with atmospheric pressure plasmas}, volume={72}, ISSN={["0040-5175"]}, DOI={10.1177/004051750207200605}, abstractNote={Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O2 plasmas for selected exposure time intervals. Scanning electron microscopy anal ysis of the fabrics shows no apparent changes in the plasma-treated nylon fiber surfaces, but significant surface morphological changes for the polypropylene. Surface analyses of the nylon filaments reveal small differences in the surface carbon and oxygen contents between the treated and control groups. The surface oxygen and nitrogen content of the polypropylene fabric increases significantly after treatment in both He and He-O2 plasmas. There is a slight decrease in nylon fabric tensile strength after treatment in He plasma for 3 minutes, while. there is no significant change in tensile strength of the nylon fabric treated with He-O2 after exposure times of up to 8 minutes.}, number={6}, journal={TEXTILE RESEARCH JOURNAL}, author={McCord, MG and Hwang, YJ and Hauser, PJ and Qiu, Y and Cuomo, JJ and Hankins, OE and Bourham, MA and Canup, LK}, year={2002}, month={Jun}, pages={491–498} }
 @article{cai_hwang_park_zhang_mccord_qiu_2002, title={Preliminary investigation of atmospheric pressure plasma-aided desizing for cotton fabrics}, volume={2}, number={12}, journal={AATCC Review}, author={Cai, Z. S. and Hwang, Y. J. and Park, Y. C. and Zhang, C. Y. and McCord, M. and Qiu, Y. P.}, year={2002}, pages={18–21} }
 @article{qiu_zhang_hwang_bures_mccord_2002, title={The effect of atmospheric pressure helium plasma treatment on the surface and mechanical properties of ultrahigh-modulus polyethylene fibers}, volume={16}, ISSN={["0169-4243"]}, DOI={10.1163/15685610252771185}, abstractNote={Ultrahigh-modulus polyethylene fibers were treated with atmospheric pressure He plasma on a capacitively coupled device at a frequency of 7.5 kHz and a He partial vapor pressure of 3.43 × 103 Pa. The fibers were treated for 0, 1, and 2 min. Microscopic analysis showed that the surfaces of the fibers treated with He plasma were etched and that the 2-min He plasma-treated group had rougher surfaces than the 1-min He plasma-treated group. XPS analysis showed a 200% increase in the oxygen content and a 200% increase in the concentration of C—O bonds (from 11.4% to 31%) and the appearance of C=O bonds (from 0% to 7.6%) on the surface of plasma-treated fibers for the 2-min He plasma-treated group. In the microbond test, the 2-min He plasma-treated group had a 100% increase of interfacial shear strength over that of the control group, while the 1-min He plasma-treated group did not show a significant difference from the control group. The 2-min He plasma-treated group also showed a 14% higher single-fiber tensile strength than the control group.}, number={1}, journal={JOURNAL OF ADHESION SCIENCE AND TECHNOLOGY}, author={Qiu, Y and Zhang, C and Hwang, YJ and Bures, BL and McCord, M}, year={2002}, pages={99–107} }