ABSTRACT
The initial interest in the production of plastics evolved from the desire to create synthetic rubber. The basic building block during these early polymerization reaction attempts was the water-insoluble monomer, butadiene. An emulsion of the monomer was developed by adding a surfactant and homogenizing the mixture. An initiator caused the attachment of the monomer molecules, resulting in larger molecules termed polymers. Today the science of polymerization has grown extraordinarily to include ABS resins, acetal resins, acetate fibers, fiber-reinforced composites, foamed plastics, and many others. These polymers may then be used to form a wide variety of products such as wood glue, carton sealants, paint, paper coatings, water-proofing materials, carpet backing, as well as in the production of more commonly observed products including pipe, bottles, plasticwares, computer cases, desk organizing items, and many others. The importance of these items to the populace cannot be understated. As a result, the quality of the products is of great importance, which, in turn, feeds back to the original control of the polymer characteristics during production. The physical analysis of these suspensions and the resulting plastic precursors can influence upstream processibility, e.g., pellet formation, and, ultimately, the final product characteristics and quality. This chapter will review one aspect of the physical characterization of the polymers and its products-particle size measurement. From the smallest sizes of polymers during the polymerization reaction, to larger sizes of the pellets used in extrusion, the size range generally includes 0.003 to 1000 µm (and possibly larger). The technique to be discussed is light scattering as applied to static (diffraction) and dynamic (Brownian motion) measurements. Several examples of the potential applications will be provided, as well as an overview of the more recently accepted approaches of analyzing the scattering information.
