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Full-Text Articles in Materials Science and Engineering
Solution Chemistry Control To Make Well Defined Submicron Continuous Fibres By Electrospinning: The (Ch3ch2ch2o)4ti/Acoh/Poly(N-Vinylpyrrolidone) System, Gustavo F. Larsen, Maciej Skotak
Solution Chemistry Control To Make Well Defined Submicron Continuous Fibres By Electrospinning: The (Ch3ch2ch2o)4ti/Acoh/Poly(N-Vinylpyrrolidone) System, Gustavo F. Larsen, Maciej Skotak
Papers in Materials Science
The (CH3CH2CH2O)4Ti/AcOH/poly(N-vinylpyrrolidone) system has been shown to yield suitable formulations for electrohydrodynamic (EHD) processing into continuous fibres and particles. The EHD processability of this, and generally most sol–gel-based formulations, into well defined fibres and particles with narrow submicron-range diameter distributions depends not only on the EHD process variables (electric field and flow rates), but also on the stability of key physical properties (e.g., conductivity, viscosity, surface tension, density and dielectric constant) of the sol over time. Sols that were almost certainly still undergoing hydrolysis and condensation reactions have been processed via EHD by many research groups to make materials with …
A Direct Correlation Function For Mesomorphic Polymers And Its Application To The ‘Smectic’ Phase Of Isotactic Polypropylene, Y Cohen, Ravi F. Saraf
A Direct Correlation Function For Mesomorphic Polymers And Its Application To The ‘Smectic’ Phase Of Isotactic Polypropylene, Y Cohen, Ravi F. Saraf
Papers in Materials Science
A general model to calculate the structure of a smectic to nematic-like order in polymer systems is proposed. The model is limited to well-aligned molecules with respect to each other. It is especially suited for systems where the packing between neighboring chains is described by liquid-like disorder with axial registration in the chain-axis direction. In such a case the diffraction pattern from the oriented structure exhibits broad liquid-like reflections on the equatorial but sharper reflections on the layer lines. An Ornstein-Zernike approach is adopted to calculate the inter-chain packing and inter-chain registration, where the direct correlation function of packing and …
Simulation Of The Growth Of Cvd Films, Jacob J. Thiart, Vladimir Hlavacek, Hendrik J. Viljoen
Simulation Of The Growth Of Cvd Films, Jacob J. Thiart, Vladimir Hlavacek, Hendrik J. Viljoen
Papers in Materials Science
Chemical vapor deposition (CVD) is the preferred method of manufacture for solid films used in many industrially important thin and thick film applications. Requirements for the physical, mechanical and electrical properties of these films are becoming increasingly difficult to achieve, and deposition morphology plays an important role in this regard. Recently, we proposed a continuum model describing the evolution of a gassolid interface during atmospheric pressure CVD (Viljoen er al., 1994). A linear stability analysis (LSA) was used to determine the effect of reactor conditions on planar growth stability. The present paper discusses numerical solution of this model, and uses …
Analysis Of Transport Phenomena In The Coating Of Fibers By Cvd, J H. Scholtz, J E. Gatica, Hendrik J. Viljoen
Analysis Of Transport Phenomena In The Coating Of Fibers By Cvd, J H. Scholtz, J E. Gatica, Hendrik J. Viljoen
Papers in Materials Science
Inorganic coated fibres produced by chemical vapour deposition find several technological applications. In this CVD process, a filler core is mounted in a reactor between two electrodes. Reactive gases flow over the substrate and react near or on the fibre surface to form the desired coating. Experience has showed that, quality deposition can only be obtained over a small range of the governing parameters: these parameters are, however, difficult to control. In the present, study a mathematical model is developed for the reactor configuration under consideration. The different mass and energy transport mechanisms are compared and their influence on the …