ABSTRACT
Melts that tend to supercool cannot be pastillated or prilled in a straightforward fashion. This is described in Sec. 6.2. The cause of the problem is explained in Sec. 6.3. ‘‘Anticrystalline’’ clusters are present above the melting point. These clusters hinder normal crystallization. This phenomenon occurs in organic melts having viscosities in the range 102-1 N sec m2 and having relatively complicatedmolecular structures. For complicatedmolecular structures, it is not easy to stack the molecules one on top of the other as in crystallization. An abnormal viscosity increase on approaching the melting point downward is an indication for the occurrence of ‘‘anticrystalline’’ clusters. This is treated in Sec. 6.4 and a number of examples are given. Sec. 6.5 deals with equipment for the crystallization of melts that tend to supercool. Pastilles can be made in a Sandvik unit, whereas rods are produced in a twin-screw extruder. Finally, the drown-out ofmelts to get granules is described. Examples of pastille production and rod production are given in Secs. 6.6 through 6.8.
