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Pressure Cell (pressure + cell)

Distribution by Scientific Domains
Chemistry40%

Selected Abstracts

Hydrostatic low-range pressure applications of the Paris,Edinburgh cell utilizing polymer gaskets for diffuse X-ray scattering measurements

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2007
Karena W. Chapman
The use of a polymeric Torlon (polyamide,imide) gasket material in a Paris,Edinburgh pressure cell for in situ high-pressure X-ray scattering measurements is demonstrated. The relatively low bulk modulus of the gasket allows for fine control of the sample pressure over the range 0.01,0.42,GPa. The quality of the data obtained in this way is suitable for Bragg and pair distribution function analysis. [source]

DSC as a valuable tool for the grease laboratory

LUBRICATION SCIENCE, Issue 3 2000
Martin Josef Pohlen
Abstract There is a need to reduce both the time and cost involved in research and development for lubricating greases. Most of the normal test methods used to characterise a grease are long-term tests, but it is important to develop screening tests that also give reliable information. Thermal analysis is one such way to fulfil these requirements. In the present work, a differential scanning calorimeter (DSC) with a normal pressure cell was used in a grease laboratory. By varying the atmosphere and the heating rate, different tests were worked out. The effects of changing physical parameters, such as viscosity and thickener structure, or chemical parameters, such as additives and thickener types, were examined. These methods can be used for controlling raw materials, improvement of grease formulations and production processes, development of new products, as a replacement for the oxidation bomb (ASTM D-942, DIN 51 808), and as a screening test for the FE9 life (DIN 51 821) test rig. [source]

Dynamics of Foaming of Polystyrene Particles

MACROMOLECULAR SYMPOSIA, Issue 1 2006
Gabriela Salejova
Abstract September 24, 2006 Summary: In this work, we address the industrially relevant problem of the foaming of expandable polystyrene (PS) impregnated by pentane as a traditional down-stream processing in the suspension polymerization of styrene. Once the polystyrene foam is formed by means of a proper foaming agent, e.g., pentane or fluoro- or chloro-hydrocarbons, the blowing agent diffuses out from the cellular structure. Environmental efforts call for the reduced consumption of blowing agents. The dynamics of foaming of polystyrene particles was recorded video-microscopically in our laboratory as the sequence of images of expanding particle located in the small pressure cell placed under the microscope with sufficient depth of focus. The amount of pentane sorbed in PS was controlled by the length of the impregnation period and was determined independently by gravimetric measurements. Strong dependence of the structure of the produced foam and of the foaming dynamics on the amount of sorbed pentane, temperature and particle size is reported and explanations for some observed foaming phenomena are provided. [source]

Vibrational properties of single walled carbon nanotubes under pressure from Raman scattering experiments and molecular dynamics simulations

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007
In-Hwan Choi
Abstract We have investigated theoretically and experimentally the pressure dependent structural and vibrational properties of single-walled carbon nanotubes (SWNT). Bundles of SWNTs are studied inside a diamond anvil high pressure cell with micro-Raman scattering. The tube diameter and size distribution are determined from the radial breathing modes (RBM) of the tubes. The pressure coefficient and linewidth of one of the high frequency C,C bond stretching modes was found to change suddenly at ,3 GPa which is well below the structural transformation pressure (Pc) for the tubes in our sample. Molecular dynamics simulations were used to calculate the vibrational density of states of SWNTs as a function of pressure. Our simulations suggest that the experimental results can be explained by a softening of a low-frequency optical mode of the SWNTs , the "squashing" mode , and the dynamical effect of this softening on other phonon modes. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Density Measurements of Fluids and Their Mixtures at High Pressure

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2007
A. M. F. Palavra
Abstract The principles of the isochoric method are described, as well as the different variants of this method that can be considered according to the technique used to determine the amount of fluid inside the high pressure cell. An automated isochoric apparatus to measure the density of binary mixtures is presented. Accurate isochoric measurements of density of pure fluids, involving molecules like methanol, and mixtures, such as nitrogen plus methane and a multicomponent system with a composition representative of the U.S.A. commercial Gulf Coast natural gas, are analyzed. Moreover, the effect of the thermal degradation of fluids at high temperatures on the accuracy of the density measurements is also discussed. [source]