Fabrication processes aggregates

The implications of texture on the properties exhibited by a material are discussed later in this chapter. It can be seen that the properties of polycrystaUine aggregates with a sufficiently large number of grains, possessing a completely random orientation distribution, are macroscopically isotropic (independent of direction), even though the crystallites themselves may be anisotropic. Fabrication processes such as extrusion, rolling, and pressing, act to remove this isotropy. 

As introduced above, much effort has been applied to electrospun polymer nanofibers to comprehend the fundamental phenomena of fabrication process as well as the physical and chemical properties from the material science viewpoint. Consequently, researchers are able to flexibly control the fiber component, morphology, and aggregate structure, which have provided much impetus to the dream of realizing the applications of electrospun nanofibers [2, 30, 35]. Particularly, electrospinning nanofibers have provided important evidence of the potential roles in solving the energy and environmental issues, which are the most important factors that influence fhe sociefy in the twenty-first century. 

The formation of ordered two- and three-dimensional microstructuies in dispersions and in liquid systems has an influence on a broad range of products and processes. For example, microcapsules, vesicles, and liposomes can be used for controlled drug dehvery, for the contaimnent of inks and adhesives, and for the isolation of toxic wastes. In addition, surfactants continue to be important for enhanced oil recovery, ore beneficiation, and lubrication. Ceramic processing and sol-gel techniques for the fabrication of amorphous or ordered materials with special properties involve a rich variety of colloidal phenomena, ranging from the production of monodispersed particles with controlled surface chemistry to the thermodynamics and dynamics of formation of aggregates and microciystallites. 

---