Particle properties, relationship

Although both of these models provide a reasonable description of the precipitation polymerization process, they do not illustrate the relationship between the reactor variables and the polymer particle properties. 

The appropriate decarbonylation of surface carbonyl species can lead to the retention of the metal frame. When the original metal frame is preserved under reaction conditions, and it is properly characterized, a direct structure-catalytic properties relationship can be established, and the catalytic behavior of supported metaUic clusters can be differentiated from that of the supported metallic particles. 

Expressions for minimum fluidizing velocify can be derived by examining fhe relationship between the velocity of a fluid passing through a packed bed of particles and the resultant pressure drop across the bed. Consequently it is necessary to define a number of bulk particle properties which influence fluidized bed behaviour. 

With the advent of advanced characterization techniques such as multiple detector liquid exclusion chromatography and - C Fourier transform nuclear magnetic resonance spectroscopy, the study of structure/property relationships in polymers has become technically feasible (l -(5). Understanding the relationship between structure and properties alone does not always allow for the solution of problems encountered in commercial polymer synthesis. Certain processes, of which emulsion polymerization is one, are controlled by variables which exert a large influence on polymer infrastructure (sequence distribution, tacticity, branching, enchainment) and hence properties. In addition, because the emulsion polymerization takes place in an heterophase system and because the product is an aqueous dispersion, it is important to understand which performance characteristics are influended by the colloidal state, (i.e., particle size and size distribution) and which by the polymer infrastructure. 

The third characteristic entered in Table II reflects the exactness of the theoretical relationship between particle properties and experimental results. Except in special cases, a rigorous theoretical linkage will improve the quality of information derived from a fractionation experiment. 

Both of these effects refer to a high surface activity and specific surface of the filler particles [26, 27, 47]. In view of a deeper understanding of such structure-property relationships of filled rubbers it is useful to consider the morphological and energetic surface structure of carbon black particles as well as the primary and secondary aggregate structure in rubber more closely-... 

Efremov and Vakhrushev25 suggested that k — /(l/e,t7L, particle properties). Darton and Harrison21 derived an empirical relationship for k as... 

Because of the importance of size-dependent property changes to the materials sciences, size-property relationships have been studied in detail for some systems. For example, for semiconductors, size effects become important when the particle diameter is close to the Bohr diameter of excitons in the bulk phase. Generally, semiconductor size quantization effects (relevant for naturally occurring metal sulfides, for example) appear when particles are less than 10 nm in diameter (Vogel and Urban 1997). 

Compaction Microlevel Processes Compaction is a forming process controlled by mechanical properties of the feed in relationship to applied stresses and strains. Microlevel processes are controlled by particle properties such as friction, hardness, size, shape, surface energy, and elastic modulus (Fig. 21-86). The performance of compaction techniques is controlled by the ability of the particulate phase to uniformly transmit stress, and the relationship between applied stress and the compaction and strength characteristics of the final compacted particulate phase. 

Becu, L. Sautereau, H. Maazouz, A. Gerard, J.F. Pabon, M. Pichot, C. Synthesis and structure-property relationships of acrylic core-shell particle-toughened epoxy networks. Polym. Adv. Technol. 1995, 6, 316-325. 

The DE and combined FE/DE methods are interesting, since they are able to provide complementary information on the particle scale (54,64). In particular, the relationship between particle properties (such as Young s modulus and yield stress) and powder properties may be elucidated. In this manner, it has been shown that the Heckel s parameter (65) (also referred to as the yield pressure) indeed reflects the yield stress of individual particles provided that the ratio between the Young s modulus and yield stress is sufficiently high (Fig. 7B) (64). For lower ratios, the Heckel s parameter rather reflects the Young s modulus. 

If all the material values are known, the sinking power Psink and D can be calculated and thence the stirrer power can be determined using equation (5.31). If, however, the necessary details are not available, model experiments with the original material system are necessary, with which a representative sinking power, also for particle collectives with broad particle size distributions, can be determined. The dependence of the power ratio on the Iteo.g number has first to be determined, for which knowledge of the particle properties is not necessary. D and Rco 9 can be immediately converted into one another. For this the known relationship (5.31) is transformed into ... 

Here we report preliminary results on the multiple fluorescence emission of 1 and 2. From structure-property relationships, solvent effect and temperature effect studies, we are able to show that the multiple emission is from the emission of free squaraine in solution, the emission of the solute-solvent complex and the emission of a twisted relaxed excited state. Further solvent effect study using 2 as a model shows that squaraine forms strong solute-solvent complexes with alcoholic solvent molecules. Analogous complex-ation process is also detected between 1 and the hydroxy groups on the macromolecular chains of poly(vinyl formal). The Important role of this complexation process on the stabilization mechanism of particles of 1 in polymer solution is discussed. 

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