Mesophase concept

Theocaris PS (1983) Mesophase concept in composite materials. Springer, Berlin Heidelberg New York, p 3... 

Theocaris, P. S. The Mesophase Concept in Composites Springer-Verlag, Berlin, Germany, 1987 Chapter III. 

Theocaris, PS., The Mesophase Concept in Composites. Springer, New York, NY, 1987. Lhotellier, F.C. and Brinson, H.F., Matrix-fiber stress transfer in composite materials elasto-plastic model with an interphase layer. Compos. Struct., 10, 281-301 (1988). Whitney, J.M. and Drzal, L.T., Axisymmetric stress distribution around an isolated fiber fragment. In Toughened Composites. American Society for Testing and Materials, Philadelphia, PA. 1987, STP 937, pp. 179-196. 

P.S. Theocaris. Mesophase concept in composites. In Polymers—Properties and Applications. Springer Series. Springer Verlag, New York, NY, 1987. ISBN-10 0387150528. 

In view of this disagreement, as well as of evidence from polymer mesophases and MD simulations, we also propose an alternative model, based on the concept that the attractive interactions are so short-lived as to be effectively delocalized. As a consequence, bridges separating consecutive bundles are also taken into account in the evaluation of the average stem length of the growing crystal, in addition to the crystalline stems and to the loops... 

The concept of interfacial mesophases promoting spontaneous emulsification (21.22) can be applied to the Tagat TO - Miglyol 812 system, where stable liquid crystalline dispersion phases are adequate to promote the process of self-emulsification. The stability of the resulting emulsion systems can also be accounted for by liquid crystalline interface stabilisation (23.24). Phase separation of material as observed above 55f surfactant, in conjuction with the increased viscosities of such systems, will inhibit the dynamics of the self-emulsification process and hence the quality of self-emulsified systems declines when the surfactant concentration is increased above 55. ... 

Comparson of the transitions observed by differential scanning calorimetry in membranes of M. laidlawii and in water dispersions of the lipids from the membranes support the concept that most of the lipids exist as a smectic mesophase in the membranes. The evidence for a bilayer structure is straightforward in this case. Lipid transition temperatures are a function of fatty acid composition and correlate well with biological properties. The calorimeter possesses advantages over high resolution NMR for M. laidlawii, and perhaps in many other systems, because the data can be interpreted less ambiguously. In M. laidlawii membranes the bilayer appears to be compatible with the same physical properties observed in other membranes—a red-shifted ORD, lack of ft structure in the infrared, reversible dissociation by detergents, and poorly... 

Additionally, the abilities of our model are exemplified by calculating X-ray patterns from PTFE (Phase I) and a smectic LC-phase of a polyester using the concepts of chain segmentation and space-averaged electron delocalization mentioned above. Thus it is verified that our model describes a wide range of different macromolecular structures covering the whole scale from crystals over mesophases up to polymer melts. 

Collective segmental rotation is considered to be the natural form gaining conformational entropy as the essential factor for stabilizing mesophases or liquid-crystalline structures. Despite the approximate character of our conception it should be possible to identify the significant characteristics of the intermolecular segmental arrangement in mesophases, in liquid crystals or in a polymer melt. 

Discussion. We can now propose a coarse description of the paraffinic medium in a lamellar lyotropic mesophase (potassium laurate-water). Fast translational diffusion, with D 10"6 at 90 °C, occurs while the chain conformation changes. The characteristic times of the chain deformations are distributed up to 3.10"6 sec at 90 °C. Presence of the soap-water interface and of neighboring molecules limits the number of conformations accessible to the chains. These findings confirm the concept of the paraffinic medium as an anisotropic liquid. One must also compare the frequencies of the slowest deformation mode (106 Hz) and of the local diffusive jump (109 Hz). When one molecule wants to slip by the side of another, the way has to be free. If the swinging motions of the molecules, or their slowest deformation modes, were uncorrelated, the molecules would have to wait about 10"6 sec between two diffusive jumps. The rapid diffusion could then be understood if the slow motions were collective motions in the lamellae. In this respect, the slow motions could depend on the macroscopic structure (lamellar or cylindrical, for example)... 

The origins and development of the concept of carbonaceous mesophase, as derived from discotic aromatic nematic liquid crystals, enable applications to be made to industrial processes. The world availability of pitch materials is such that there is an abundance of pitch which produces cokes of little commercial value. A major incentive for research into the Chemistry of mesophase formation is the commercial up-grading of such pitches and the development of specialized pitches. Structure in cokes is described in terms of optical texture. 

The carbonaceous mesophase is the intermediate material formed during carbonization of parent pitch and leading to the resultant coke. The discovery and development of the concept of mesophase over the last twenty years must represent one of the most significant advances in carbon science, Mesophase is a term borrowed from the science of conventional liquid crystals and means "intermediate phase". The term "carbonaceous mesophase" is distinguished from the term 1nematic... 

Following the third concept described above, of using electron-donor-ac-ceptor interactions for inducing smectic mesophases in SCLCPs, Pugh et al. presented the thioether monomers XXV-n as electron-donating and the sulfone derivatives XXVI-n as electron-accepting entities in a preliminary paper, as shown in Fig. 15 [80]. 

Despite that the silicate-surfactant mesophase formation resembles the phase separation normally observed in surfactant-polyelecholyte systems, it is interesting to note that it is stiU possible to make qualitative predictions about the influence of inorganic-surfactant phase behavior based on models developed for dilute surfactant systems. The packing parameter concept - is based on a geomettic model that relates the geomehy of the individual surfactant molecule to the shape of the supramolecular aggregate structures most likely to form. N, is defined as... 

In the following paragraph, the basic theoretical concepts for analysing scattering patterns from partially ordered systems (membranes, lipid mesophases) and particles (proteins) in solution are discussed. 

As the new field expanded and novel concepts were recognized other names were being used to designate the entire class or its subgroups. The examples include ordered or periodic mesoporous materials, mesostructures, mesophases, etc. and they have been used interchangeably. In here we adopted the abbreviated form mesoporous materials as referring to materials with uniform mesopores. 

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