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Surface modification of polytetrafluoroethylene film using single liquid electrode atmospheric-pressure glow discharge

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Chinese Physics B 2011年第6期20卷 329-335页

作者：周澜吕国华陈维庞华张谷令杨思泽 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences College of Science Minzu University of China Fujian Key Laboratory for Plasma and Magnetic Resonance Department of Aeronautics School of Physics and Mechanical & Electrical Engineering Xiamen University

Polytetrafluoroethylene films are treated by room temperature helium atmospheric pressure plasma plumes, which are generated with a home-made single liquid electrode plasma device. After plasma treatment, the water contact angle of polytetrafiuoroethylene fihn drops from 114° to 46° and the surface free energy increases from 22.0 mJ/m2 to 59.1 mJ/m2. The optical emission spectrum indicates that there are reactive species such as O2＋, O and He in the plasma plume. After plasma treatment, a highly crosslinking structure is formed on the fihn surface and the oxygen element is incorporated into the film surface in the forms of C O-C-, -C=O, and O C=O groups. Over a period of 10 days, the contact angle of the treated film is recovered by only about 10°, which indicates that the plasma surface modification is stable with time.

关键词： single liquid electrode atmospheric pressure glow discharge wettability ageing effect

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Shear wave velocity-based evaluation and design of stone column improved ground for liquefaction mitigation

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Earthquake Engineering and Engineering Vibration 2017年第2期16卷 247-261页

作者： Zhou Yanguo Sun Zhengbo Chen Jie Chen Yunmin Chen Renpeng MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering Institute of Geotechnical Engineering Zhejiang University Hangzhou 310058 China

The evaluation and design of stone column improvement ground for liquefaction mitigation is a challenging issue for the state of practice. In this paper, a shear wave velocity-based approach is proposed based on the well-defined correlations of liquefaction resistance （CRR）-shear wave velocity （V）-void ratio （e） of sandy soils, and the values of parameters in this approach are recommended for preliminary design purpose when site specific values are not available. The detailed procedures of pre- and post-improvement liquefaction evaluations and stone column design are given. According to this approach, the required level of ground improvement will be met once the target V of soil is raised high enough （i.e., no less than the critical velocity） to resist the given earthquake loading according to the CRR-V relationship, and then this requirement is transferred to the control of target void ratio （i.e., the critical e） according to the V-e relationship. As this approach relies on the densification of the surrounding soil instead of the whole improved ground and is conservative by nature, specific considerations of the densification mechanism and effect are given, and the effects of drainage and reinforcement of stone columns are also discussed. A case study of a thermal power plant in Indonesia is introduced, where the effectiveness of stone column improved ground was evaluated by the proposed V-based method and compared with the SPT-based evaluation. This improved ground performed well and experienced no liquefaction during subsequent strong earthquakes.

关键词： Liquefaction mitigation Stone column Shear wave velocity Void ratio Densification ageing effect

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A low power 50Hz argon plasma for surface modification of polytetrafluoroethylene

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Plasma Science and Technology 2022年第11期24卷 1-13页

作者： Yen Theng LAU Wee Siong CHIU Hong Chun LEE Haw Jiunn WOO Oi Hoong CHIN Teck Yong TOU Department of Physics Faculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Faculty of Engineering Multimedia UniversityPersiaran CyberjayaCyberjaya 63100Malaysia

The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene(PTFE)film is presented in this *** current–voltage behavior of the discharge and time-varying intensity of the discharge showed that a DC glow discharge was generated in reversed polarity at every *** discharge power between 0.5 and 1 W,the measured electron temperature and density were 2–3 eV and∼10^(8) cm^(−3),*** optical emission spectrum of the argon plasma showed presence of some‘impurity species’such as OH,N_(2) and H,which presumably originated from the residual air in the discharge *** exposure of PTFE films to the argon glow plasma at pressure 120 Pa and discharge power 0.5 to 1 W,the water contact angle reduced by 4%to 20%from the original 114°at pristine condition,which confirms improvement of its surface *** increase in wettability was attributed to incorporation of oxygen-containing functional groups on the treated surface and concomitant reduction in fluorine as revealed by the XPS analysis and increase in surface roughness analyzed from the atomic force *** upon storage in ambient air showed retention of the induced increase in surface wettability.

关键词： 50 Hz glow discharge plasma surface treatment PTFE hydrophobic recovery ageing effect

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