The Microstructure of Diene Polymers. II. Polyisoprenes and Polybutadienes Prepared at High Pressures

Abstract The rapid bulk polymerization of isoprene at room temperature under high hydrostatic pressure was apparently first observed by Bridgman and Conant. A more extensive investigation by Conant and Tongberg established the free radical nature of the polymerization (peroxide catalysis and hydroquinone inhibition). The latter workers also noted the solubility and elasticity of polymers made to moderate conversion and the insoluble crumbly nature (gelation) of the polymers made to very high conversion. In view of the well known effect of increased pressure in driving chemical reactions in the direction of the products of least specific volume, it is of interest to consider the possibility that diene polymers made at high pressures may be different in microstructure from polymers made at comparable temperatures but near atmospheric pressure.

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Microstructural Characterization of High-Pressure Oxidized Si1-x Gex /Si Heterolayers

MRS Proceedings ◽

10.1557/proc-280-545 ◽

1992 ◽

Vol 280 ◽

Author(s):

N. David Theodore ◽

Gordon Tam

Keyword(s):

Heterojunction Bipolar Transistors ◽

Atmospheric Pressure ◽

High Pressures ◽

Microstructural Characterization ◽

Bipolar Transistors ◽

Pure Silicon ◽

Device Structures ◽

Microstructural Behavior ◽

Very High

ABSTRACTSiGe alloys have recently been of interest for fabrication of heterojunction bipolar transistors using pre-existing or modified silicon-processing technology. These devices are faster than devices using pure silicon. Because of the interest in developing SiGe device structures, various elements of processing relevant to fabrication of the devices are being investigated. One such element has been the use of thermal oxidation for isolation of SiGe devices. Utilization of the technique requires an understanding of oxidation behavior of SiGe layers under a variety of oxidation conditions. Past studies in the literature have investigated the oxidation of SiGe at atmospheric pressure or at very high pressures (∼650–1300 atmospheres). The present study investigates the wet-oxidation of SiGe structures at intermediate pressures (∼25 atmospheres) and temperatures (∼750°C). Unlike atmospheric oxidation, most of the Ge (from SiGe) remains in the oxidized silicon (SiO2) in the form of GeO2. Occasional segregation of Ge to the oxidizing interface is noted. The microstructural behavior of partially and entirely oxidized structures is presented.

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Quantum Chemical Calculation of Reactions Involving C20, C60, Graphene and H2O

International Journal of Nanoscience ◽

10.1142/s0219581x19400088 ◽

2019 ◽

Vol 18 (03n04) ◽

pp. 1940008 ◽

Cited By ~ 2

Author(s):

N. A. Poklonski ◽

S. V. Ratkevich ◽

S. A. Vyrko ◽

A. T. Vlassov ◽

Nguyen Ngoc Hieu

Keyword(s):

Gibbs Energy ◽

Chemical Reactions ◽

Atmospheric Pressure ◽

Room Temperature ◽

Hydrogen Release ◽

Graphene Sheets ◽

Water Molecules ◽

Hydroxyl Groups ◽

Chemical Calculation ◽

Assisted Decomposition

Calculations of chemical reactions between C20, C60, hydrogen and water molecules are carried out using the PM3 method. Reactions with a hydrogen release at room temperature and atmospheric pressure are identified by the Gibbs energy change. The hydrogen release can be raised by increasing the number of water molecules in chlorine-assisted decomposition of fullerenes. Calculations of the Gibbs energy of chemical reactions involving water molecules between two parallel curved graphene sheets are carried out using DFT with the functional UB3LYP. During pumping between plates of an electric capacitor designed from curved graphene sheets, the water vapor with the assistance of external illumination is enriched by electrically neutral hydroxyl groups (OH)0.

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Effect of High Hydrostatic Pressure on the Permeability of Elastomers to Water

Rubber Chemistry and Technology ◽

10.5254/1.3547139 ◽

1966 ◽

Vol 39 (4) ◽

pp. 1298-1307 ◽

Cited By ~ 2

Author(s):

Alexander Lebovits

Keyword(s):

Hydrostatic Pressure ◽

Thermodynamic Analysis ◽

Atmospheric Pressure ◽

High Hydrostatic Pressure ◽

Polymeric Materials ◽

Butyl Rubber ◽

Pressurized Water ◽

Simple Method ◽

Increased Pressure

Abstract The permeability of butyl rubber to pressurized water was measured at 10,000 psi hydrostatic pressure using a relatively simple method which consisted of constructing pouches from rubber, filling these with desiccant and exposing them to pressurized water. At this high hydrostatic pressure the permeability was found to be smaller than at atmospheric pressure which suggests the suitability of butyl rubber for the construction of hydrophone boots used at great depths. Similar results found by other investigators for other polymeric materials are cited. A thermodynamic analysis of the process of permeation by activated diffusion was made and a mechanism was discussed which explains the decrease in permeability of butyl rubber to water with increased pressure.

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Cold Consolidation of Powder by Hydrostatic Extrusion

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1974_188_075_02 ◽

1974 ◽

Vol 188 (1) ◽

pp. 639-645 ◽

Cited By ~ 1

Author(s):

R. L. Hewitt ◽

W. Wallace ◽

M. C. Demalherbe

Keyword(s):

Strain Hardening ◽

Metal Powder ◽

Room Temperature ◽

High Pressures ◽

Hydrostatic Extrusion ◽

Bonding Mechanism ◽

Similar Composition ◽

Isostatic Compaction ◽

Very High ◽

Strength Improvement

The isostatic compaction and hydrostatic extrusion of two atomized powders, namely Alcoa grade 1202 aluminium and Atomet 28 iron, are described and it is shown that the extrusion pressures for these powders may be 50-100 per cent greater than for an equivalent wrought material. Results of mechanical testing and metallographic and fractographic examinations of the extruded aluminium compacts are presented which show that good bonding can be developed by hydrostatic extrusion at ratios of 6·25 and that the resultant strengths can be higher than that of wrought material of a similar composition. This strength improvement is attributed to the strain hardening undergone by the materials during compaction. An interpretation of the bonding mechanism is also given. Although it has been shown that isostatic compaction and hydrostatic extrusion can be combined to produce well-bonded bar material from metal powder at room temperature, it is suggested that the method is limited by the very high pressures that would be required to produce materials of commercial interest.

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An experimental determination of the melting curves of argon and nitrogen into the 10000 atm region

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1954.0211 ◽

1954 ◽

Vol 225 (1162) ◽

pp. 393-405 ◽

Cited By ~ 23

Keyword(s):

Low Temperatures ◽

Room Temperature ◽

Small Volume ◽

High Pressures ◽

Steel Tube ◽

Melting Curves ◽

New Apparatus ◽

Very High ◽

Small Steel

A new apparatus for measuring melting curves at low temperatures and very high pressures is described. It is essentially a combined cryostat and high-pressure intensifier connected by a single junction at room temperature. The pressure is produced in a number of stages culminating in a single intensification stroke on to a small volume of gas maintained at low temperatures in a long steel tube. Solidification and melting are detected in this tube by means of a small steel pellet, which may be moved by an external magnetiċ field when the substance is fluid. Experiments have been carried out on argon and nitrogen. The solid-fluid equilibrium line has been extended to 8250 atm at 234° K for argon, and to 9100 atm at 180° K for nitrogen.

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Room-Temperature Silicon Nitrides Prepared with Very High Rates (>50 nm/s) in Atmospheric-Pressure Very High-Frequency Plasma

Plasma Chemistry and Plasma Processing ◽

10.1007/s11090-010-9242-7 ◽

2010 ◽

Vol 30 (5) ◽

pp. 579-590 ◽

Cited By ~ 6

Author(s):

Hiroaki Kakiuchi ◽

Hiromasa Ohmi ◽

Kei Nakamura ◽

Yoshihito Yamaguchi ◽

Kiyoshi Yasutake

Keyword(s):

Atmospheric Pressure ◽

High Frequency ◽

Room Temperature ◽

Silicon Nitrides ◽

Very High Frequency ◽

High Frequency Plasma ◽

Frequency Plasma ◽

Very High

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Ultimate H2 and CH4 adsorption in slit-like carbon nanopores at 298 K: a molecular dynamics study

RSC Advances ◽

10.1039/c4ra02553a ◽

2014 ◽

Vol 4 (44) ◽

pp. 22848-22855 ◽

Cited By ~ 11

Author(s):

Eric Poirier

Keyword(s):

Molecular Dynamics ◽

Room Temperature ◽

High Pressures ◽

Gas Adsorption ◽

Methane Storage ◽

Molecular Dynamics Calculations ◽

Ch4 Adsorption ◽

Slit Pores ◽

Very High ◽

Carbon Slit Pores

Molecular dynamics calculations of gas adsorption in ideal carbon slit pores provide new insights into the physical limits of nanocarbons for hydrogen and methane storage at very high pressures and room temperature.

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