Time pressure mechanism

Transformations in the Solid State. From a practical standpoint, the most important soHd-state transformation of PB involves the irreversible conversion of its metastable form II developed during melt crystallization into the stable form I. This transformation is affected by the polymer molecular weight and tacticity as well as by temperature, pressure, mechanical stress, and the presence of impurities and additives (38,39). At room temperature, half-times of the transformation range between 4 and 45 h with an average half-time of 22—25 h (39). The process can be significantly accelerated by annealing articles made of PB at temperatures below 90°C, by ultrasonic or y-ray irradiation, and by utilizing various additives. Conversion of... 

Returning now to the subject of the chapter, in addition to appropriate retentive characteristics, a potential stationary phase must have other key physical characteristics before it can be considered suitable for use in LC. It is extremely important that the stationary phase is completely insoluble (or virtually so) in all solvents that are likely to be used as a mobile phase. Furthermore, it must be insensitive to changes in pH and be capable of assuming the range of interactive characteristics that are necessary for the retention of all types of solutes. In addition, the material must be available as solid particles a few microns in diameter, so that it can be packed into a column and at the same time be mechanically strong enough to sustain bed pressures of 6,000 p.s.i. or more. It is clear that the need for versatile interactive characteristics, virtually universal solvent insolubility together with other critical physical characteristics severely restricts the choice of materials suitable for LC stationary phases. 

The pressure necessary to produce a specific stress in a vessel depends on the thickness of the vessel, the vessel diameter, and the mechanical properties of the vessel wall.7 For cylindrical vessels with the pressure p not exceeding 0.385 times the mechanical strength of the material SM... 

A photoelectric conversion device 10 is formed in a p-type HgCdTe substrate 11 and a CCD 20 is formed in a p-type silicon substrate 13. Indium electrodes 4a and 4b, which are connected to the photoelectric conversion device and the CCD, respectively, are covered on their sides with shape-memory metal layers 5a and 5b. Pressure bonding is used to couple the photoelectric conversion device to the CCD. Thereafter, the temperature is raised to return the shape-memory metal to its original shape, at the same time releasing mechanical stress in the indium electrodes. 

In the above experiments, deionized water was used as the external solution. As described in the previous section, the addition of salts to the solution decreased the photostimulated dilation of the gels. If the bending motion in the electric field was due to the osmotic pressure mechanism, the addition of salt would also suppress the motion. This is not the case. On the contrary, the response time of the bending motion was accelerated by the addition of salts to the external solution. The bending rate in the solution containing 2 x lO mole/l NaCl was 1.5 mm/sec, which is 4 time faster than the rate in the absence of NaCl. The result indicates that the bending motion in the electric field is not due to the osmotic pressure mechanism. 

Extruder Retention time, pressure, thermal and mechanical energy input Expansion ability, texture Kokini (1991)... 

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