ABSTRACT

This chapter describes several processes that might be applied to the encapsulation of pesticides and discusses their versatility and limitations with respect to possible capsule shell compositions. The encapsulation techniques under consideration fall under the general heading of physical processes in that nozzle devices are involved, although to categorize them as such might be misleading, as chemical processing is frequently utilized. The criterion of nonreactivity of the shell formulation with the material being encapsulated is quite obvious, although a slow, limited reaction may be permissible in some instances. Shell polymers dissolved in volatile solvents may be hardened by evaporation of the solvent as the capsules are projected from the encapsulating nozzle. The various encapsulation processes to be described require that the material to be encapsulated be pumped through the nozzle devices. Postencapsulation treatment may also be appropriate, particularly with respect to controlled release applications.