Hollow metal cylinders produced from diacetylenic lipid

2000 ◽  
Vol 15 (11) ◽  
pp. 2368-2374 ◽  
Author(s):  
Dan Zabetakis
Keyword(s):  
Electrical Properties ◽  
Packing Density ◽  
Parallel Plate ◽  
Volume Fraction ◽  
Bulk Material ◽  
Critical Volume ◽  
Critical Volume Fraction ◽  
Specific Packing ◽  
Improved Technique ◽  
Hollow Metal

A method was presented for the formation and metallization of cylindrical tubules from a diacetylenic lipid. This improved technique allowed for the production of metal microcylinders without the need for preliminary lipid purification and in large quantities. The physical and electrical properties of the material were investigated, and composites were used to form parallel plate capacitors. A comparison of the conductivity of the bulk material with the derived conductivity of a composite showing electromagnetic percolation showed the proportionality of the specific packing density and the critical volume fraction characteristic of percolating systems.

scholarly journals The AC and DC Conductivity of Nanocomposites

2007 ◽  
Vol 2007 ◽  
pp. 1-9 ◽  
Author(s):  
David S. McLachlan ◽  
Godfrey Sauti
Keyword(s):  
Electrical Properties ◽  
Volume Fraction ◽  
Matrix Material ◽  
Dc Conductivity ◽  
Critical Volume ◽  
Matrix Structure ◽  
Electrical Measurements ◽  
Conducting Component ◽  
Critical Volume Fraction ◽  
The Matrix

The microstructures of binary (conductor-insulator) composites, containing nanoparticles, will usually have one of two basic structures. The first is the matrix structure where the nanoparticles (granules) are embedded in and always coated by the matrix material and there are no particle-particle contacts. The AC and DC conductivity of this microstructure is usually described by the Maxwell-Wagner/Hashin-Shtrikman or Bricklayer model. The second is a percolation structure, which can be thought to be made up by randomly packing the two types of granules (not necessarily the same size) together. In percolation systems, there exits a critical volume fraction below which the electrical properties are dominated by the insulating component and above which the conducting component dominates. Such percolation systems are best analyzed using the two-exponent phenomenological percolation equation (TEPPE). This paper discusses all of the above and addresses the problem of how to distinguish among the microstructures using electrical measurements.

scholarly journals Effects of Bentonite Nanoclay and Cetyltrimethyl Ammonium Bromide Modified Bentonite Nanoclay on Phase Inversion of Water-in-Oil Emulsions

2020 ◽  
Vol 4 (1) ◽  
pp. 2
Author(s):  
Sileola B. Ogunlaja ◽  
Rajinder Pal
Keyword(s):  
Contact Angle ◽  
Aqueous Phase ◽  
Phase Inversion ◽  
Volume Fraction ◽  
Critical Volume ◽  
Ammonium Bromide ◽  
Cetyltrimethyl Ammonium Bromide ◽  
Modified Bentonite ◽  
Critical Volume Fraction ◽  
Cetyltrimethyl Ammonium

The effects of unmodified and modified bentonite nanoclays (with various degrees of surfactant modification) on the catastrophic phase inversion from water-in-oil (W/O) emulsion to oil-in-water (O/W) emulsion were determined experimentally. The bentonite nanoclay (NC-Bt) was suspended in the aqueous phase, and the critical volume fraction of water where phase inversion from W/O to O/W emulsion took place was determined through conductivity measurements. Cetyltrimethyl ammonium bromide (CTAB) was used as a surfactant to modify the nanoclay. The adsorption of CTAB onto nanoclay had a strong influence on the contact angle and the critical volume fraction of water where phase inversion took place. The modification of the nanoclay brought about by the adsorption of CTAB increased the three-phase contact angle (measured through the aqueous phase), thereby making it more hydrophobic, and prolonged the phase inversion point. CTAB alone and CTAB-modified nanoclay delayed the phase inversion process in a similar manner, showing a strong dependence on the CTAB concentration.

Compressive deformation and damage of Mg-based metallic glass interpenetrating phase composite containing 30–70 vol% titanium

2010 ◽  
Vol 25 (11) ◽  
pp. 2192-2196 ◽  
Author(s):  
Yu Sun ◽  
Haifeng Zhang ◽  
Aimin Wang ◽  
Huameng Fu ◽  
Zhuangqi Hu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metallic Glass ◽  
Fracture Strength ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Critical Volume ◽  
Strengthening Mechanisms ◽  
Phase Volume ◽  
Phase Volume Fraction ◽  
Critical Volume Fraction

Mg-based metallic glass interpenetrating phase composites (IPCs) containing 30–70 vol% titanium was fabricated in this study. The effects of reinforced phase volume fraction and interspace on the mechanical properties were investigated systematically. With increasing the volume fraction of titanium, the fracture strength and strain increased up to 1860 MPa and 44%, respectively. The results showed that the critical volume fraction (around 40%) of Ti metal should be required for significantly improving plasticity of IPC. Decreasing the interspace of the titanium phase could lead to enhancement of yield and fracture strength. The deformation behavior and strengthening mechanisms were discussed in detail.

Dilution and Suppression of Partially Premixed Flames in Normal and Microgravity for Different Fuels

2006 ◽  
Author(s):  
Andrew J. Lock ◽  
Alejandro Briones ◽  
Suresh K. Aggarwal ◽  
Ishwar K. Puri ◽  
Uday G. Hegde
Keyword(s):  
Volume Fraction ◽  
Premixed Flames ◽  
Dilution Effect ◽  
Critical Volume ◽  
Area Of Interest ◽  
Air Stream ◽  
Partially Premixed Flames ◽  
Critical Volume Fraction ◽  
Partially Premixed ◽  
Fuel Stream

The suppression of fires and flames is an important area of interest for both terrestrial and space based applications. In this investigation we elucidate the relative efficacy of fuel and air stream inert diluents for suppressing laminar partially premixed flames. A comparison of the effects of fuel and air stream dilution are also made with other fuels. Both counterflow and coflow flames are investigated, with both normal and zerogravity conditions considered for coflow flames. Simulations are conducted for both the counterflow and coflow flames, while experimental observations are made on the coflowing flames. With fuel or air stream dilution, coflow flames are observed to move downstream from the burner after overcoming initial heat transfer coupling. Further increases in diluent result in increases in the flame liftoff height until blow off occurs. The flame liftoff height and the critical volume fraction of extinguishing agent at blow out vary with both equivalence ratio and with the stream in which diluents are introduced. Nonpremixed methane-air flames are more difficult to extinguish than partially premixed flames with fuel stream dilution; whereas, partially premixed methane-air flames are more resistant to extinction than nonpremixed flames with air stream dilution. This difference in efficacy of the fuel and air stream dilution is attributed to the action of the diluent. In leaner partially premixed flames with fuel stream dilution and richer partially premixed flames with air stream dilution the effect of the diluent is to replace the deficient reactant in the system, thus starving the flame. In leaner partially premixed flames with air stream dilution and richer partially premixed flames with fuel stream dilution the effect of the diluent is purely thermal in that it absorbs heat from the flame, until combustion may no longer be sustained. The dilution effect is more effective than the thermal effect. When gravity is eliminated from the 2-D flame the liftoff height decreases and the critical volume fraction of diluent for blow off is also decreased.

Criterion for Dendrite Fragmentation of Steel under Imposition of Linear Traveling EMS

2010 ◽  
Vol 148-149 ◽  
pp. 84-91
Author(s):  
Jin Chen ◽  
Zhi-Jian Su ◽  
Keiji Nakajima ◽  
Ji Cheng He
Keyword(s):  
Fluid Flow ◽  
Mushy Zone ◽  
Volume Fraction ◽  
Critical Volume ◽  
Solute Content ◽  
Dendrite Fragmentation ◽  
Critical Volume Fraction

In the fragmentation theory of T. Campanella et al, the local remelting of dendrite arms is induced by the solute-rich fluid flow. Based on this theory, the effects of linear EMS intensity and solute content on CET of steel are investigated. The conclusions are as follows: The criterion for dendrite fragmentation under linear EMS is derived based on dendrite fragmentation theory by T. Campanella et al. And the criterion is verified with steel experiments. It is valid for steel under the Linear EMS. Investigation is carried out on relation between critical volume fraction of solid and solute content at the time of dendrite fragmentation (CET occurrence). It is concluded that critical volume fraction of solid is small with low EMS intensity and it decreases with the increase of solute content (C, Mn). The reason is that it causes that flow in the mushy zone becomes small which leads to CET occurrence difficult.

Numerical Analysis of the GF/UHMWPEF Interply Hybrid NOL Ring Critical Volume Fraction

2012 ◽  
Vol 457-458 ◽  
pp. 449-452
Author(s):  
Ming Lin Xu ◽  
Xiao Qing Wu ◽  
Ming Kang An
Keyword(s):  
Finite Element ◽  
Volume Fraction ◽  
Critical Volume ◽  
Tooth Contact Analysis ◽  
Breaking Strain ◽  
Finite Element Software ◽  
Critical Volume Fraction ◽  
The Matrix ◽  
The Relationship ◽  
Strain Model

The tensile test of NOL ring composites with different interply hybrid ratio is simulated by finite element software. The relationship between the stress of Naval Ordnance Laboratory(NOL) ring and the volume fraction of UHMWPEF is linear when the matrix suffering from the equal loading, but tower suddenly appears at the point of 56.25% which is about the critical volume fraction. The critical volume fraction of hybrid NOL ring is figured out on the basis of the constant strain model. By contrast, the results of the Finite Element Method (FEM) and constant strain model have subtle differences. Tooth contact analysis can exactly predict the stress of the interply hybrid NOL ring and the critical volume fraction of GF in interply hybrid NOL ring which has lower breaking strain than UHMWPEF does.

Critical volume fraction of crystallinity for conductivity percolation in phosphorus‐doped Si:F:H alloys

1982 ◽  
Vol 40 (6) ◽  
pp. 534-535 ◽  
Author(s):  
R. Tsu ◽  
J. Gonzalez‐Hernandez ◽  
S. S. Chao ◽  
S. C. Lee ◽  
K. Tanaka
Keyword(s):  
Volume Fraction ◽  
Critical Volume ◽  
Critical Volume Fraction ◽  
Phosphorus Doped
Sign in / Sign up

Export Citation Format

Share Document