Structure and Properties of Deforming Polymers

Because of their molecular structure, polymers are by far the most complex fluids engineers will encounter. Therefore, what seems trivial when dealing with Newtonian fluids, is a complex experimental and mathematical exercise for a rheologist dealing with polymeric melts. An important aspect of any rheologist’s work is to find relations between deformation and stresses for various well defined conditions, such as transient shear flows, step strain, creep, and oscillatory shear flow, to name a few. These relations, also called material functions, are determined using different types of rheometric techniques. This chapter will introduce the reader to the causes of the various phenomena only observed with plastics and the relation of these effects to the molecular architecture of polymer melts.