Image acquisition technology

Flory, Robert

doi:10.1109/proc.1985.13188

Cited by 31 publications

(20 citation statements)

References 19 publications

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“…The higher the aspect ratio of the rods, the lower the concentration at which a nematic phase begins to appear. A more accurate estimate of this critical concentration is provided by the lattice theory of Flory, which is based only on excluded volume effects [545,546]. For both theories, the degree of orientation in the nematic phase, expressed through the scalar order parameter S, is high.…”

Section: Liquid Crystalsmentioning

confidence: 99%

“…The lower limit of the two-phase region was derived from polarizing microscope observations, whereas the upper one was determined by assuming that, according to Matheson [554], the minimum viscosity marks the transition from the two-phase condition to the anisotropic system. The two-phase region is significantly broader than theoretical prediction from Flory's theory for rigid rods with a large aspect ratio [545,546,555] Onogi and coworkers used rheo-optical techniques to record the intensity of transmitted polarized light through the sample during shear flow and on cessation offlow [557,558]. The concentration dependence of viscosity may change dramatically with increasing shear rate and, hence, the flow curves relative to different concentrations may intersect in the power-law region [553,556,560].…”

Section: Liquid Crystalsmentioning

confidence: 99%

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Rheology of polysaccharide systems

Lapasin

Pricl

1995

Rheology of Industrial Polysaccharides: Theory and Applications

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The transport properties and, specifically, the rheological behavior of real and complex materials such as polysaccharide systems can be significantly affected by several factors, mainly related to molecular and supermolecular features. Most of these factors are common to all polymeric systems, as they have universal character; others are peculiar to carbohydrate polymers. If we bear in mind the concepts discussed in §1.4, we can easily imagine for polysaccharides a variety of structural conditions much wider than that generally observed for synthetic polymers. On both molecular and supermolecular scales, polysaccharides possess special characteristics that reflect specific behavior so that different classes of materials can be identified.Let us consider the molecular scale first: at this level, the polymer backbone and its related features, such as its length in solution, shape, stitfuess and the eventual presence of ionizable groups, playa major role in determining the macroscopic properties of the system, including its rheology. Many of these molecular parameters correlate among themselves (e.g. chain stitfuess and length); others must be combined with external factors such as, for instance, the characteristics of the solvent medium. These latter may, in turn, exert an influence on the conformation adopted by the macromolecule in the medium itself, as well as on the possibility of forming supermolecular structures. In other words, changes in ionic strength, the nature of counterions, temperature or other solvent parameters may induce a conformational transition, thus modifying the hydrodynamic resistance of the macromolecule to flow. Also, if the polymer concentration is high enough, the variations described above may promote structural changes at a supermolecular level and, accordingly, modifications in the rheological behavior. Before leaving this brief comment on solvent characteristics we must mention the viscosity although, R. Lapasin et al. (eds.), Rheology of Industrial Polysaccharides: Theory and Applications

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Section: Liquid Crystalsmentioning

confidence: 99%

Section: Liquid Crystalsmentioning

confidence: 99%

Rheology of polysaccharide systems

Lapasin

Pricl

1995

Rheology of Industrial Polysaccharides: Theory and Applications

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“…We have designed several random copolymers that are melt miscible with iPP using the conformational asymmetry concept. For a random copolymer that obeys Gaussian statistics, (a' ) = c 6iPT (3) where Oi and Bi are the volume fraction and symmetry parameter for repeat unit i. Based on small-angle neutron scattering (SANS)" and density measurements," p$p z 5.2 X 106 cm-' at 175°C.…”

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confidence: 99%

Isotactic polypropylene‐compatible block copolymer

Bates

Kumar

Schulz

1995

J Polym Sci B Polym Phys

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“…The number average molecular weight of the PBLG sample was 12.3 x 104 and its number average axial ratio x calculated by means of the following equation [2] was 54.4, where M is the molecular weight of the sample. The phase diagrams of PBLG in DMF, in chloroform, and in dioxane are shown in figures 4, 5 and 6, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Flory [2] has shown theoretically that these critical concentrations, A and B points, are only functions of the axial ratio, x, of rigid rod-like molecules and are independent of the intermolecular interaction if the solution is athermal. Recently, he proposed a revised theory for the polydispersed systems [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Phase separation of poly(?-benzyl L-glutamate) to liquid crystal and isotropic solution in various helicogenic solvents

Sakamoto

1984

Colloid & Polymer Sci

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Solvent effects on the phase separation of poly(y-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations, v~, at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observed v2 value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observed v2 values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, the v~ value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such as m-cresol that dissolves the polymer almost molecularly, the v~ is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.

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Image acquisition technology

Cited by 31 publications

References 19 publications

Rheology of polysaccharide systems

Rheology of polysaccharide systems

Isotactic polypropylene‐compatible block copolymer

Phase separation of poly(?-benzyl L-glutamate) to liquid crystal and isotropic solution in various helicogenic solvents

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