Skip to main content
main-content

Über dieses Buch

The present monograph is intended as an introduction into a field which certainly did not receive proper attention in the past. It is one of the aims of this book to verify this suppo­ sition. The author hopes to show that the technique of the measurement of flow birefringence can fulfil an important com­ plementary task in polymer melt rheology. From this point it is expected that the present monograph will attract the atten­ tion of polymer scientists in general, and of rheologists and process engineers in particular. Certainly, the fourth chapter will appeal to the latter group. As a teacher in polymer science and technology the author wants to address also the group of the graduate students. In fact, the standard knowledge acquired during usual university studies in chemistry, physics or engineering does not enable a quick start of research activities in the field of polymer melt rheology. Certainly, in this typically interdisciplinary field everyone can lay emphasis on matters which are familar to hirn because of his preceding education. Significant research activities, however, can only be generated on the basis of a more universal knowledge. In the absence of this knowledge beginners have to rely upon the guidance of their supervisors for an unduly long period. Otherwise they take the risk of losing too much of their costly time. This holds in particular for the experimentalists who cannot be dispensed from being familiar with the necessary theoretical background.

Inhaltsverzeichnis

Frontmatter

1. Survey of Experimental Results

Abstract
As may be clear from the title of this monograph, the flow birefringence of polymer melts will be treated in the general context of the rheology of these fluid systems. As a matter of fact, it does not seem desirable to treat the flow birefringence technique as an independent method by which polymeric fluids can be characterized. For such a purpose the flow birefringence method suffers too much from a number of shortcomings. First of all, only clear fluids can be investigated. This means that systems containing filler particles must be excluded from the investigation. (Fortunately, pure crystalline polymers which are opaque at room temperature as a consequence of the microcrystalline structure, become clear above their melting points.) Another drawback of this method is that it is indirect. Rheologists are interested in the interrelations between stresses and strains: rheology is part of mechanics and not of optics.
Hermann Janeschitz-Kriegl

2. Quasi-Molecular Phenomenological Theories

Abstract
As has been pointed out by A.S. Lodge1) , the constitutive equation for the ideal rubber forms an advantageous starting point for the construction of suitable constitutive equations for polymeric fluids. On the other hand, it is well known that real rubbery materials do not obey the ideal equations derived from the statistical theory. From these facts it appears worth while to start the chapter on the theory of rubber-like liquids with a discussion of the main problems arising in the description of rubber elasticity.
Hermann Janeschitz-Kriegl

3. Prospects for Predictions on a Molecular Basis

Abstract
It goes almost without saying that there is a great interest in any quantitative interrelation between molecular parameters like chain stiffness or molecular mass distribution on one hand and rheological properties under varying conditions on the other hand. This interest is certainly not particularly characteristic for fundamentalists, it is shared by a great number of industrialists. A modern trend goes in the direction of producing polymer grades, the so-called tailored resins, for very specific purposes. In this connection manufacturers want to know how a molecular mass distribution has to be fashioned in order to realize a certain specific rheological effect such as strain hardening during extension. Even with general purpose grades questions can arise, which must be solved in terms of more or less pronounced adaptations in the chemical structure of the polymer. In particular, insufficiently defined long chain branching has been discussed as a source of variations in processing performance.
Hermann Janeschitz-Kriegl

4. Industrial Applications

Abstract
For this chapter only two topics are selected, viz molecular orientation in stretched amorphous samples and the birefringence patterns in injection moulded strips of amorphous polymers. No reference is made to typical hydrodynamic problems like the interpretation of birefringence distributions in non-uniform flow fields as occurring in the entrance region of capillaries etc. The reason for this omission is that the present author does not feel competent in solving these problems with the aid of adequate constitutive equations. Beautiful qualitative pictures are found in Chang D. Han’s book1) and in the papers by Teikichi Arai and coworkers?2).
Hermann Janeschitz-Kriegl

Backmatter

Weitere Informationen