Structure formation crystallization

Figure 2.4 Scheme for investigating structure formation (crystallization and melting) in semicrystalline polymers through the technique of irradiation-induced cross-iinking and fixation at temperatures in the melting range. After fixation of the amorphous phase in each case, the structure formed can be studied by TEM [6, 7]... 

Structured laundry liquids are currently available in Europe and were recently introduced in the United States [50,51]. These products typically contain high levels of surfactants and builder salts, as well as enzymes and other additives. In the presence of high ionic strength, the combination of certain anionic and nonionic surfactants form lamellar liquid crystals. Under the microscope (electron microscope, freeze fracturing) these appear as round droplets with an onion-like, multilayered structure. Formation of these droplets or sperulites permits the incorporation of high levels of surfactants and builders in a pourable liquid form. Stability of the dispersion is enhanced by the addition of polymers that absorb onto the droplet surface to reduce aggregation. 

The Mechanism of Structure Formation During the Induction Period of Crystallization from the Unstable State... 

On the basis of the above described studies, we propose a model for the structure formation mechanism during the induction period when a polymer is crystallized from the unstable state. Figure 24 shows a schematic diagram of... 

Fig. 31 Structural formation model for the initial stage of polymer crystallization [19], N G nucleation and growth of oriented domains, SD spinodal decomposition into oriented and unoriented domains, Tb, Ts, and Tx bimodal, spinodal, and crystallization temperatures, respectively I isotropic, N smectic, and C crystalline...

Floudas et al. [135] also studied the isothermal crystallization of PEO and PCL blocks within PS-b-PEO-h-PCL star triblock copolymers. In these systems the crystallization occurs from a homogeneous melt Avrami indexes higher than 1 are always observed since the crystallization drives structure formation and does not occur under confined conditions. A reduction in the equilibrium melting temperature in the star block copolymers was also observed. 

Quinacridones, for example, depend on hydrogen bonds to define their crystal structure during crystal formation. 

In this level, the fundamental tasks required to convert the raw materials into the final product are identified. All tasks are related to property differences. Siirola (1996) has presented the following hierarchy of property differences molecular identity, amount, composition, phase, temperature/pressure, form. This list of tasks is not very well suited for food properties. Common tasks for food processes are decontamination (e.g. pasteurization and sterilization) and structure formation (e.g. emulsification, size reduction of dispersed phase in an emulsion, crystallization, interfacial adsorption/desorption). 

I Abdelmoty, F Albericio, LA Carpino, BM Foxman, SA Kates. Structural studies of reagents for peptide bond formation crystal and molecular structures of HBTU and HATU. Lett Pept Sci 1, 57, 1994. 

Imai, M., Kaji, K. and Kanaya, T., Structural formation of polyethylene terephthalate) during the induction period of crystallization. 3. Evolution of density fluctuations to lamellar crystal, Macromolecules, 27, 7103-7108 (1994). 

The fibers exhibit a fine structure consisting of large crystals separated by areas of poorly oriented, amorphous regions with many crystal nuclei at a pronounced skin/core character, which is a consequence of a complex structure formation mechanism. The nuclei grow into large crystals upon heating. 

If the local structure formation discussed in this chapter is not specific to bmimX ILs but applies to ILs in general, ILs may not be genuine liquids in the conventional sense. They might be better called nano-structured fluid or crystal liquid. They may form a new meso-phase that is distinct from the liquid... 

Many compounds of technetium and rhenium are of analogous composition and of corresponding physical and chemical properties. Because of the very similar ionic radii, isotypic crystal structure formation of analogous compounds could often be observed. Technetium remarkably differs from manganese by the high stability of pertechnetate compared with permanganate. Moreover, divalent technetium does not exist as a hydrated ion but only as a stabilized complex. 

Raag, R., Swanson, B. A., Poulos, T.L., and Ortiz de Montellano, P. R. (1990) Formation, crystal structure and rearrangement of a cytochrome P- iron-phenyl complex. Biochemistry 29, 8119-8126. 

Thus, it has been demonstrated that the combination of weak interactions is useful for the design of topochemical polymerization to yield a new type of stereoregular polymer. The weak intermolecular interactions are tolerant of a variety of crystal structure formations and induce a different molecular stack-... 

M. lijima, D.G.A. Nelson, Y. Pan, A.T. Kreinbrink, M. Adachi, T. Goto, Y. Mori waki, Fluoride analysis of apatite crystals with a central planar OCP inclusion Concerning the role of F" ions on apatite/OCP/apatite structure formation, Calcif. Tissue Int. 59 (1996) 377-384. 

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