Short Crystallinity, effect

Quinapyramine sulfate and chloride are bitter, odorless, white to pale yellow crystalline powders. The sulfate salt is readily soluble in water and the chloride salt is soluble in boiling water up to a concentration of 2%. The sulfate salt has a rapid onset of action but a short duration effect, whereas the chloride salt has a long-acting effect and is used for prophylaxis. 

A number of studies have introduced the reactive element into the aluminides by ion implantation. The author considers this approach to be of limited value since, as discussed by Pint and Hobbs [27], the high local concentration of reactive element can stabilize the transition aluminas and, at high temperatures, has a short-lived effect. More importantly, from a fundamental standpoint, the implantation process can have a profound effect on the nature of the exposed surface. For example, Schumann [28] has shown that Y implantation into single-crystal NiAl results in a 45 nm thick, finegrained crystalline region which is disordered. 

In this Chapter the basic approaches used to describe nematic liquid crystalline (NLC) systems in slab geometries under the effect of confinement are introduced. We review both, the microscopic and macroscopic approaches, however, the emphasis is on the latter. We also show the correspondence between the approaches on different levels. Special attention is devoted to effects of the confinement on the LC order and consequently to the interactions arising from that. More precise descriptions of the techniques and also more detailed results have been already published elsewhere [9-12,15-18]. In the following Section we first shortly review the microscopic origin of order and define the appropriate order parameter. Then we review the basic microscopic and macroscopic theoretical approaches to describe LC systems. In the third Section we describe in short the effect of confinement in two different types of NLC systems. The fourth Section is devoted to macroscopic interactions between confining walls, especially the ones characteristic for ordered systems. We conclude the Chapter with the discussion on the observability of structural and fluctuation forces in NLC systems. 

The crystallinity of TPs is important for their short term yield strength. Unless the crystallinity is impeded, increased molecular weight generally also increases the yield strength. However, the cross-linking of TSs increases their yield strength substantially but has an adverse effect upon toughness. 

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... 

Crystallinity often has little if any effect on 7A, but with some polymers crystallized under certain conditions, the 7A value is raised (78,79). The increase appears to be caused either by polymer being restricted to short amorphous segments between two crystallites or by stresses put on the amorphous chain sequences as a result of the crystallization process. In either case the mobility is restricted, so higher temperatures are required to restore it. Thus quench cooling tends to increase 7A whereas annealing reduces TK back to the value typical of the amorphous polymer. 

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