Polymer Processing and Rheology

This chapter is devoted to the presentation of the fundamental rheological properties of polymers and their processing technologies. Measurements of the rheological properties offer a fast and reliable way to determine molecular weight distribution and long-chain branching, which, in combination with the processing conditions, have a decisive influence on the end-use product properties. Shear viscosity, elongational viscosity, normal stress differences, stress relaxation, and some other measures and rheological phenomena, of relevance to polymer processing, are discussed. The most widely used polymer processing technologies of extrusion and injection molding are discussed with some details. The discussion includes key features of equipment used and design and operation challenges. Brief descriptions are presented on calendering, compression molding, blow molding, thermoforming, rotational molding, fiber spinning, and additive manufacturing. It is argued that computer-aided flow analysis and rheological measurements are necessary for equipment design, troubleshooting, and optimization in the processing of thermoplastics.