Morphological change mechanism crystal

This anisotropic distribution of the occluded additive provides a second independent method of confirming the absolute configuration assigned by means of the morphological changes, once the mechanism of adsorption is known. This principle will be met again in the growth of centrosymmetric crystals. 

The systems described above are by deLnition metastable and are affected by temperature Luc-tuations. Two other factors inLuencing solubility are the effect of change in crystal morphology and the creation of a higher-energy surface on particles by mechanical stress (grinding). 

The effects of morphology (i.e., crystallization rate) (6,7, 8) on the mechanical properties of semicrystalline polymers has been studied without observation of a transition from ductile to brittle failure behavior in unoriented samples of similar crystallinity. Often variations in ductlity are observed as spherulite size is varied, but this is normally confounded with sizable changes in percent crystallinity. This report demonstrates that a semicrystalline polymer, poly(hexamethylene sebacate) (HMS) may exhibit either ductile or brittle behavior dependent upon thermal history in a manner not directly related to volume relaxation or percent crystallinity. 

Surface nano-morphology changes of photoreactive molecular crystals are an attractive area of research, because the phenomena could potentially be applied to photodriven nanometer-scale devices and provide important information on crystal-line-state reaction mechanisms and dynamics [2a, 21]. As described in Section 25.3.2, the single crystal of lEt, in which the CpEt rings have no reorientation freedom in the crystal, tends to collapse and degrade as the reaction proceeds. This observation for the crystal of lEt can be explained by the local stress induced by the photoreaction that is not suitably released by the crystal lattice. In such a crystal, does the surface morphology of the crystal change ... 

The morphology and mechanical properties of PVA were studied using atactic poly(vinyl alcohol) (at-PVA) dry gel films prepared by crystallization from solutions in dimethyl sulfoxide and water mixtures. The NMR measurements suggested changes in the hydrogen bonds. ... 

Mechanisms of crystal growth, morphological changes, kinetics, defect structure, and surface lattice parameters have been reported on numerous organic (Overney 1991 Mao 1997 Last 1998), inorganic (Ott 1994 Hillner 1994 Bosbach 1995 Marinkovic... 

In the crystallization of polymorphs influence with some special additives is observed(i-3). Such effect is due to the relative change of nucleation rate and growth rate of the polymorphs, the effect also contains the change in transformation rate(4,5). Furthermore, a morphological change occurs in many cases. On the other hand, a crystallographic approach has been applied to effect of various type of additives on crystal growth(6-fl). However, the effect of additives espeddly on the kinetic behavior of polymorphism has not usually been treated quantitatively and the mechanisms are not known. 

C02-induced crystallization of polymers presents a unique, tunable degree of morphological control of the polymeric matrix, as revealed by CRM. Control over the operating conditions enables control of the diffusivity of CO2 combined with control over the kinetics of crystalhzation. This degree of control enables the distribution of morphological changes in the polymer to be tailored, which may facilitate the formation of novel materials with a skin-core morphology with possible unique mechanical properties. 

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