During the past decade, the application of microscopical methods and associated techniques has contributed much to the knowledge of heterogeneous polymer systems. Plasticized polymer, pigmented polymer, and polymerpolymer systems have all been examined successfully by the microscopical technique.

Many of these hybrid polymer systems were developed, manufactured, and used extensively, long before any clear understanding of the mechanisms involved in their compounding was obtained. This discussion will bring together some of the technological details of the role of the microscope as it aids our understanding of heterogeneous polymer systems and the morphology — performance relationship of these materials.