Papers by Keyword: PTFE

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Authors: N.Z.F. Mukhtar, Mohamad Rusop, Saifollah Abdullah
Abstract: PTFE is a polymer of the type of Teflon. This polymer is from fluoropolymer family and made from monomer tetrafluoroethylene by polymerization. PTFE have properties that make them very useful in many application such as high melting point, extremely low friction of coefficient, very good chemical resistance, maximum mechanical resistance, non reactive polymer and good insulation properties. Therefore, this paper will report the study on commercial PTFE as an excellent remarkable polymer. The characterization will take over to analysis this polymer, respectively via Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infra - Red Spectroscopy (FTIR) and X-Ray Diffraction (XRD). It was found that PTFE have spherical shape like branches with crystalline phase.
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Authors: Thorsten Hoffmann, Dieter Lehmann, Martin Anders, Thorsten Schmidt, Thorsten Heinze, Markus Michael
Abstract: During the irradiation of high molecular weight poly (tetrafluoroethylene) (PTFE) in presence of oxygen perfluoroalkyl (peroxy) radicals and functional groups are formed which allow chemical coupling reactions (cc = chemical compatibilized) with oils and plastics. The micropowder resulting from the irradiation of PTFE are used in base oils to improve the tribological properties significantly if oil molecules are covalently linked to primary PTFE particles in the oil dispersion. These oil-PTFE-cc-dispersions show primarily anti-wear (AW) properties. The use of additional reactive groups (e.g. phosphite groups) in the oil gives the dispersions extreme pressure (EP) properties additionally. This article demonstrates the usefulness of the oil-PTFE-cc-dispersions in rolling bearings and in ropes using phosphite-modified PTFE products as additive in lubricants. The investigations are completed by wear tests with different contact geometries. A model is shown to explain the effect of phosphite groups on 100Cr6 metallic surfaces.Keyword s: PTFE, high performance lubricant, oil-PTFE-cc dispersion
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Authors: Dimitri Aslanidis, Akiyoshi Osaka, Satoshi Hayakawa, Kanji Tsuru
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Authors: Hong Xing Xu, Xin Hua Yuan, En Bo Zhu, Shuang Lian Li, Ling Chen, Zhi Rui Han
Abstract: The polytetrafluoroethylene (PTFE) matrix composites which filled with polyphenylene sulfide (PPS) fiber, poly-p-phenelenferephthalamide (PPTA) fibre or glass fiber (GF)) and graphite at various mass fractions were prepared by the processes of mechanical blending, compression molding and sintering. The mechanical properties of the composites, such as tensile strength, impact strength and hardness were investigated. The results show that tensile strength and elongation at break markedly decrease but elasticity increases by filling with fibers. Impact strength decreases by filling with PPS and GF, and the composite displays brittle characteristic. However, the impact strength rapidly increases by filling with PPTA fiber. Hardness increases with the fibers content increases, and decreases with graphite content increases. Filling graphite into PTFE has light effect on the impact and tensile strength of composites. The tribological properties of the composites were investigated on M-2000 wear tester at dry friction condition. The wear mechanism was also discussed and the wear surfaces were examined by SEM. The result indicates that fibers which diffused in PTFE matrix wind with PTFE molecule chain, and then form grid structure. The load-bearing capacity of composites can be obviously enhanced and the trend of block fragmentations slide is inhibited, so that the tribological properties are improved markedly.
203
Authors: L. Diguet, Michel Keddam, Hisasi Takenouti, H. Mazille, Y. Cètre
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Authors: Nicolas Bosq, Nathanaël Guigo, Nicolas Sbirrazzuoli
Abstract: Polytetrafluoroethylene (PTFE) is a semi-crystalline polymer that demonstrates a very fast crystallization process on cooling. This study investigates the nonisothermal PTFE ultra-fast crystallization over a wide range of cooling rates via conventional Differential Scanning Calorimetry (DSC), Fast Scanning Calorimetry (FSC) and Ultra-Fast Scanning Calorimetry (UFSC). A new knowledge about crystallization kinetics of PTFE is obtained from the data obtained under very fast cooling rates. The shift of the melting peak to lower temperature shows that the crystals formed under fast cooling rates are slightly less stable than those produced under slower cooling rates. SEM analysis allows to observe these differences in crystal morphologies. According to the results, the crystallization is still present even for the fastest cooling rate employed and in consequences it is impossible to reach a metastable glassy state. The effective activation energy (Eα) displays a variation with the relative extent of crystallization (α) that is characteristic of a transition of PTFE crystallization from regime II to regime III around 312°C. Following the Hoffman-Lauritzen theory the Eα dependency obtained from the crystallizations under the different cooling rates was fitted in order to study the theoretical dependence of the growth rate.
201
Authors: Yu Hui Zhang, Quan Ji, Wen Fei Chen
Abstract: Radio frequency (rf) magnetron sputtering of polytetrafluoroethylene (PTFE) using argon as the working gas was used to prepare hydrophobic fluorocarbon films on a polypropylene substrate. The morphology, structure and hydrophobicity of the fluorocarbon films were analyzed by means of SEM, AFM, XPS and contact angle determination. The growth pattern in this system was a typical one-dimensional (1-D) Volmer-Weber growth mode. The films demonstrated dependence of structure and hydrophobicity on the conditions of preparation. The contact angle decreased with increasing discharge power and increased with increasing pressure. Those trends are attributed to the presence of differing proportions of -CF3, -CF2-, -CF-, and -C- in fluorocarbon thin films prepared with different energy.
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Authors: Yu Kun Fu, Chuan Jun Han, Juan Wang, Yang Yi
Abstract: In order to enhance the sealing performance of rubber core in ram blowout preventer, this paper designed a new structure of the rubber core which embedded a half-PTFE ring in the central of rubber core based on the characteristics of failure mode on the contact surface. Through carrying out the experiment on the rubber under different temperature and pressure to determine the constitutive relation of the rubber core, this paper has established the 3D model of rubber core and drill pipe, accomplished the contact finite element analysis under 20MPa and compared with the general rubber core. The results show that in the contact surface between the new rubber core and the drill pipe, the whole rubber core is in stress concentration area, and the contact stress is bigger than the values of normal core with the drill pipe. When the well blowout occurred, it will have a greater sealing pressure between the PTFE ring and the drill pipe, which plays a greater role in blowout control. For the small friction coefficient between PTFE ring and drill pipe, the scuffing is reduced from the drill pipe and the service life of rubber core is extende
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Authors: Jun Deng, Xue Tian Wang, Chi Liu
Abstract: This paper concentrates on choosing basic materials for the polarizing beam splitter in the transmitter and receiver isolation network, and considering the influence of polarizing beam splitter’s ability parameters with different basic materials through analysis the optimizations. Based on the previous study above, we also devoted to find the most suitable basic materials, for which could improve the capacity and optimize the structure of the polarizing beam splitter.
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