Blend with two completely immiscible components

The crystallizahon of a mixture of two polymers that are immiscihle over the complete composihon range presents some features that have not been previously 

At low concentrations of the low molecular weight polymer, PiB(LM), all of the polymer is rejected between the spherulites at all crystallization temperatures. As 

In the initial melts of blends of two immiscible components the noncrystallizable component is segregated in droplet domains. During crystallization the domains can 

In effect, an additional term has been added to the conventional transport and nucleation terms. The additional activation energy, E, for these additional processes can be expressed as 

With all these possibilities, modifications of the conventional growth rate can be expected in some blends.(79) It is, therefore, not surprising that the growth rate-composition relations of blends with two immiscible components are not unique and a variety of results can be expected, as is observed. 

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Both points can be achieved by adding small amounts of a third component to the blend to act as a bonding agent between the two incompatible phases. Depending on the chemical structure of both compatibilizers and components of the blends, the compatibilization mechanism is different. When the macromolecular compound is a copolymer having monomer units which are identical to, or at least compatible with, each phase, there is physical bonding. The copolymer is miscible with the two phases, creating a bond between the two completely immiscible phases. 

What is necessary with a polymer blend in order to achieve the desired breadth of transition is partial miscibility. Complete immiscibility leads to two Tgs unshifted with respect to the Tgs of the components, and complete miscibility leads to the same relatively narrow transitions observed for homopolymers. Of course, with immiscible blends, it is possible to mix two or more polymers with relatively close Tgs and achieve broad damping transitions in that way. Hourston and Hughes (33) have reported broad transitions for polyether ester-polyvinyl chloride (PVC) blends where specific interactions occur between the ether oxygens and the chlorines in the PVC leading to partial miscibility. 

Polymer blending is to combine two or more components and has superior mechanical, optical, or thermal properties than these individual polymers. From the practical and economical points of view, polymer blending from existing polymers is the most effective and convenient route to create new and useful materials with greater versatility and flexibility than the development of new polymers. Basically, three different types of blends can be distinguished completely miscible, immiscible, and partially miscible blends [1,2] as shown in Figure 2.1. 

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