Thermodynamic filler dispersion

Microdomain stmcture is a consequence of microphase separation. It is associated with processability and performance of block copolymer as TPE, pressure sensitive adhesive, etc. The size of the domain decreases as temperature increases [184,185]. At processing temperature they are in a disordered state, melt viscosity becomes low with great advantage in processability. At service temperamre, they are in ordered state and the dispersed domain of plastic blocks acts as reinforcing filler for the matrix polymer [186]. This transition is a thermodynamic transition and is controlled by counterbalanced physical factors, e.g., energetics and entropy. 

Vaterite is thermodynamically most unstable in the three crystal structures. Vaterite, however, is expected to be used in various purposes, because it has some features such as high specific surface area, high solubility, high dispersion, and small specific gravity compared with the other two crystal systems. Spherical vaterite crystals have already been reported in the presence of divalent cations [33], a surfactant [bis(2-ethylhexyl)sodium sulfate (AOT)] [32], poly(styrene-sulfonate) [34], poly(vinylalcohol) [13], and double-hydrophilic block copolymers [31]. The control of the particle size of spherical vaterite should be important for application as pigments, fillers and dentifrice. 

Blends are classified as either thermodynamically miscible or immiscible, with the latter dominating. However, imposition of a flow affects the thermodynamic equilibrium and it may enhance the miscibiUty of immiscible blends or vice-versa - there is an interrelation between rheology and thermodynamics. Similarly, flow affects the degree of deformation of the dispersed phase, thus in immiscible blends there are other interrelations between rheology and morphology, which affect the blend performance. To the complexity of polymer alloys and blends (PAB) behavior one must add the incorporation of soUds, either in the form of filler and nanofiller particles or by simple factofblendingtwocomponents with widely differenttransitiontemperatures. 

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