Pitch blending studies

This approach to pitch blending studies appeared to be successful. Careful and extended studies are obviously essential. 

Bie most common supply of carrier-free lead radioisotopes has been natural radium or thorium samples, Due to the presence of appreciable amounts of stable lead In pitch-blend which Is the principle source of radium or In thorium ores It Is necessary to obtain the carrier-free material from a sample which has previously been purified from lead. A convenient separation Is that of diffusion of the noble gas member of the radium or thorium decay chain from the parent material and its subsequent decay to radioactive lead Isotopes. Very early In the studies of radioactivity It was found that very high specific RaD(Pb ) sources could be obtained by... 

Materials obtained by pyrolysis of pitch-polysilane blends have been extensively studied as carbon materials containing Si [157-161], For some of these materials, ca. 600mAh/g of Crev for Li insertion, as well as small irreversible capacities and small hysteresis effects, were reported. It has been shown that the materials contain nanodispersion of Si-O-C and Si-O-S-C instead of nanodispersed Si particles [162-165], Furthermore, the oxygen and sulfur contents are proved to be correlated to the irreversible capacity. There is a report about the fabrication of porous Si negative electrodes with 1-D channels, where the usefulness of the fabricated negative electrodes for rechargeable microbatteries is also suggested [166],... 

The major consideration in selecting the experimental region for this study was that it include compositions that could be expected to produce acceptable pipe compounds. A second consideration was that the region be comprehensive enough to include blends containing pitch in excess of the maximum amount that could be acceptably added to pipe compounds. In other words, if the experiment was to indicate the maximum tolerable amount of pitch, then some blends containing unacceptable amounts also had to be studied. 

A mathematical transformation was made to convert the absolute amounts of each element to their relative amounts within the subregion studied. These relative amounts are called pseudocomponents (1). For example, the blend consisting of 45 percent graft, 30 percent SAN, and 25 percent pitch contains the maximum amount of pitch and minimum amounts of the other constituents. 

Two methods have been used to identify the boundary between transitional and laminar blending, and they give similar results for the value of Reynolds number at the boundary. Wichterle and Wein (1981) made visualization studies of the flow in vessels agitated by Rushton and pitched blade turbines. They deflned two Reynolds numbers the value when motion first appears and the value when all stagnant zones disappear. The second definition is used here ... 

There are a wide range of studies that investigate the production and utilization of activated carbons derived from PET [42-47]. The production of activated carbons from blends such as coal/pitch and PET [48,49], as well as the preparation of porous polyester fiber by using supercritical carbon dioxide, have also been studied [50]. 

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