Co-rotating twin screw extruder
Make sure to have a clear command of the change regulation of two or more polymers and materials in the extruding process, their mixing state, the process of their structural change, and the relationship between final mixtures and their functions.
A model that is helpful for the molding-filling process can be formed by the internal relationship among the reaction process, speed, function of extruding process and twin screw extruder structure, as well as operation condition.
The development of twin screw extruders: it was first invented in 1930s in Italy, while in the late 1960s and early 1970s, it experienced a rapid development. With the development of RPVC products, counter-rotating twin screw extruder came into being; while co-rotating twin screw extruder appeared, companying with the polymer modification. It is useful to study the twin screw extruding theory, because it can not only be applied effectively, but also has become a consensus and a hot research in the world.
One big obstacle to the industry’s adoption of HME has been that in the initial phases of development, pharmaceutical companies have limited amounts of API and no way to test it except in a full-batch mixing bowl. During the past two years, however, screw extruder design has fundamentally changed to allow small batches (e.g., 5–20 g) of candidate APIs to be tested in a continuous way, says Martin. Manufacturers now can experiment to determine whether HME is an appropriate processing method for a new drug candidate.
The pharmaceutical industry has not used HME to manufacture many of its medicines, perhaps because it has been largely unfamiliar with the process. Companies could use the technology to create many dosage forms, however, and the process could enable the manufacture of drugs that otherwise would remain unmarketed. As a continuous technique, HME likely would be favored by the US Food and Drug Administration and yield dosage forms of consistently high quality, says Martin. The process also seems to hold the promise of greater efficiency and reduced operating expenses. Given these advantages, the adoption of HME may become more widespread in the near future.