Crystallization in Some Selected Processes

The crystallization of the minor component in incompatible polymer blends starts sometimes at distinctly larger undercoolings than in the pure polymer, and proceeds in several separated steps. After a short survey on the history of the effect in the available literature, the several types and the origin of this "fractionated crystallization" as observed in some selected systems are described. The information on the blend which can be deduced from the effect is discussed, and the consequences for the blend processing and properties are investigated. 

Final product isolation in a form suitable for further processing into the final dose form of the pharmaceutical, e.g., as a tablet or an injectable solution. Secondary production of this type is sometimes done in a separate facility, with the raw material referred to as the bulk product or, more recently, the active pharmaceutical ingredient. Examples of unit operations at this stage of processing include lyophilization, precipitation, or crystallization followed by solid isolation using filtration and drying techniques. In some cases, the final product must be produced in a sterile form, which introduces additional complications when selecting suitable process equipment. 

---