Particle size reduction milling problems

The size reduction step can be the source of problems. Firstly, it is often difficult to replicate the milling and sizing processes from batch to batch which, in turn, leads to poor reproducibility. We have found that a combination of wet ball-milling, using a ceramic system, and laser particle sizing allows the production of higher quality material [67]. However, since the MIP particles are not uniform in shape, MIP columns still tend to demonstrate relatively poor flow dynamics, which result in poor chromatographic performance. In spite of this problem, the exceptional selectivity of the polymers has still made them useful. 

Reducing the course material in size in a colloid mill or by means of ultrasonic waves generally does not lead to a higher distribution ratio, i.e. to smaller particles. As it is smaller particles tend to form larger ones under the influence of mechanical forces and due to the attraction between the particles. These problems are solved to a large extent when a surface active substance and possibly a solvent are added during the reduction process. 

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