Relationships Between Polymer Rheology and Polymer Processing

Abstract Polymer products have long been used for a variety of applications in our daily lives, as well as for some more exotic applications, such as biomedical devices, superhigh- speed airplanes, and outer-space vehicles. Other applications are too numerous to mention them all here. There are many steps involved in the production of polymer products, from the synthesis of raw materials to the manufacturing of the finished products. Of the many steps involved, the fabrication (processing) step plays a pivotal role in determining the quality of the final products. Successful processing of polymeric materials requires a good understanding of their rheological behavior (Han 1976, 1981). Thus, intimate relationships exist between polymer rheology and polymer processing. In this chapter we describe briefly some of these close relationships between polymer rheology and polymer processing. Rheology is the science that deals with the deformation and flow of matter. Hence, polymer rheology is the science that deals with the deformation and flow of polymeric materials. Since there are a variety of polymeric materials, we can classify polymer rheology further into different categories, depending upon the nature of the polymeric materials; for instance, (1) the rheology of homogeneous polymers, (2) the rheology of miscible polymer blends, (3) the rheology of immiscible polymer blends, (4) the rheology of particulate-filled polymers, (5) the rheology of fiberglass-reinforced polymers, (6) the rheology of organoclay nanocomposites, (7) the rheology of polymeric foams, (8) the rheology of thermosets, (9) the rheology of block copolymers, and (10) the rheology of liquid-crystalline polymers. Each of these polymeric materials exhibits its own unique rheological characteristics. Thus, different theories are needed to interpret the experimental results of the rheological behavior of different polymeric materials. However, at present we do not have a comprehensive theory that can describe the rheological behavior of some polymeric materials and thus we must resort to empirical correlations to interpret the experimentally observed rheological behavior of those materials. It is then fair to state that a complete understanding of the rheological behavior of all polymeric materials remains quite a challenge indeed.