Macroscopic Morphology

Crosslinking of polymers is usually applied to stabilize the macroscopic morphology or shape of a material. In most cases, it results in insoluble polymeric materials, e.g., for polymeric coatings. In the chemoenzymatic strategies towards polymer networks, the enzymatic step is exclusively applied to synthesize the... 

Lohse and Gaylord (5) have examined the role of crystallite impenetrability on the Young s modulus. The crystallites are assumed to form pairs of parallel lamellae. Two macroscopic morphologies are considered ... 

Most of the previous studies on flame retardation of polymer nanocomposites are focused on the relationship between macroscopic morphologies of chars and the flammability properties. Fang et al. studied the relationship between evolution of the microstructure, viscoelasticity and graphitization degree of chars and the flammability of polymers during combustion (68). The flame retar-dancy of ABS/clay /MWNTs nanocomposites was strongly affected by the formation of a network structure. Flammability properties... 

Figure 16. Model for vesicle and bilayer control of macroscopic morphology and surface patterning, and mesolamellar structure of the aluminophosphates [206].

The deposits show nanostructures that, apart from sUghtly increased dimensions of the material, are very similar to the structure of the LLC phases they are derived from. These new electrode surfaces are adherent, macroscopically smooth (see Fig. 15) and shiny and expectedly show high specific surface areas. Variations in the deposition conditions, such as temperature and deposition potential, cause dramatic changes in the specific surface area, nanostructure and macroscopic morphology of the films, providing an additional tool to tailor the surface properties of such electrodes [62]. 

It is not the purpose of this chapter to describe compatibilization of layers of immiscible polymers in laminates. Strategies similar to those used to compatibilize intimately mixed polymer blends have also been used to prepare stable laminates and, in those cases where a chemical reaction takes place between laminate layers, similar types of chemical reaction have been used. Nevertheless, laminate macroscopic morphology is essentially hxed and formation of stable laminates is better treated as an adhesion problem. 

Fig. 3. Macroscopic and microscopic morphology of filamentous fungi. Macroscopic morphology describes the gross morphology, while microscopic morphology describes the properties (dimensions and compartmentalization) of the gross morphological forms...

The morphology of ordered mesostructured carbons is another important factor with respect to their practical applications. Various macroscopic morphologies are required, for example, films (in sensor, separation and optical applications), uniformly sized spheres (in chromatography) or transparent monoliths. Using suitable synthesis strategies, it is possible to control the external shape of the templated mesoporous carbon materials to generate powders, films and membranes, spheres, hollow spheres, rods, fibres, nanowires, nanotubes and monoliths. 

This macroscopic morphology is based on the general structures of the reaction schemes. The first aim of this chapter is to describe these and thus to trace the framework within which the detailed reaction mechanisms likely to account for the resulting chemistry will be developed. 

Effective conductivity of the membrane is related to its macroscopic morphology, viz. the random heterogeneous domain structure of polymer and solvent phases. On the basis of Gierke s cluster network model, a random network model of microporous PEMs was developed in [22]. This approach highlighted the importance of connectivity and swelling properties of pores. Random distributions of pores and channels as their interconnections were assumed. The connectivity between pores was considered as a phenomenological parameter. 

Wan] Wang, C.P., Liu, X.J., Takaku, Y, Ohnuma, L, Kainuma, R., Ishida, K., Formation of Core-Type Macroscopic Morphologies in Cu-Fe Base Alloys with Liquid Miscibility Gap , Metall. Mater. Trans. A, 35A(4), 1243-1253 (2004) (Experimental, Calculation, Morphology, Phase Diagram, Thermodyn., 31)... 

Wan] investigated the effect of C on the macroscopic morphologies in Cu-Fe alloys and established that the core-type macroscopic morphology is formed by the addition of C due to the stable miscibility gap in the liquid phase in the C-Cu-Fe system. 

The morphology of synthetic graphite is generally a function of particle size. For particles larger than about 20 pm, the macroscopic morphology is very similar to that of the coke feed used to manufacture the graphite. However, as size is reduced below about 20 pm, the basic flaky structure common to all graphites becomes apparent in the primary particle. 

The macroscopic morphology of as-prepared polyacetylene depends mainly on the catalyst concentration when homogenous catalyst systems such as Ti(OR)4-AIR a (R,R = alkyl) are employed. If the catalyst concentration is extremely low then introduction of acetylene gas at room temperature causes the pale-yellow solution to turn gradually purple, the characteristic colour of mixed cisitrans poly acetylene. The... 

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