Solid-state properties profound effect

The pharmaceutical industry has taken great interest of late in the study of polymorphism and solvatomorphism in its materials, since a strong interest in the phenomena has developed now that regulatory authorities understand that the nature of the structure adopted by a given compound upon crystallization can exert a profound effect on its solid-state properties. For a given material, the heat capacity, conductivity, volume, density, viscosity, surface tension, diffusivity, crystal... 

This difference in spatial characteristics has a profound effect upon the polymer s physical and chemical properties. In thermoplastic polymers, application of heat causes a change from a solid or glassy (amorphous) state to a flowable liquid. In thermosetting polymers, the change of state occurs from a rigid solid to a soft, rubbery composition. The glass transition temperature, Tg, ... 

Short intramolecular contacts between chalcogens and other chalcogens or other heteroatoms have been shown to influence molecular geometry, particularly planarity, in many structures of electroactive materials. Hence the position of the chalcogen atom in the material can profoundly affect its properties. For example Crouch et al 2 report the X-ray crystal structure of compound 24 (Figure 10), a candidate for an organic field-effect transistor, showing the effect of intramolecular S- F close contacts (in tandem with H F contacts) on the planarity of the molecule in the solid state. Note also the... 

The physical state of a substance (whether it is a solid, liquid, or gas) can have a profound effect on its chanical properties. In Chapter 5, we examined the general properties of gases, liquids and solids. In this chapter, we focus on the factors that influence the transformations of a substance from one phase of matter to another. While phase transformations in pure systems are examined in Section 9.1, the remainder of the chapter deals with physical changes in solutions. 

The high surface-to-volume ratio can also significantly improve thermal transfer conditions within micro-channels in two ways firstly, the convective heat transfer which takes place at the solid/fluid interface is improved via an increase in heat transfer area per unit volume and, secondly, heat transfer wifhin a small volume of fluid takes a relatively short time period to occur, enabling a thermally homogeneous state to be reached quickly. The improvement in heat transfer can certainly influence overall reaction rates and, in some cases, product selectivity. Perhaps one of the more profound effects of the efficient heat-transfer property of micro-reactors is the ability to carry potentially explosive or highly exothermic reactions in a safe way, due to the relatively small thermal mass and rapid dissipation of heat. 

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