Uniform Elongational Flow of Molten Polymers

Abstract

In this review we shall concentrate on uniaxial elongational flows which are uniform (i.e. spatially homogeneous) and may be time-dependent. We trace briefly the development of the subject from the study by Trouton (1906) through a series of errors and their correction to the beginnings of the modern period around 1950. The “early modern period”, which is characterised by the development of techniques for measuring the elongational viscosity of soft solid and highly viscous molten polymers and by the derivation of theoretical expressions for elongational viscosity, may conveniently be divided from the “late modern period” by the review of Dealy (1971). In this latter period we find that experimental techniques have been refined and their limits pushed further and further, revealing new facets of behaviour for the theorists to explain. There has also been a growing interest in unsteady flows of well-defined character both by experimenters and by theorists.