Rheological and Morphological Properties of Dispersed Polymeric Materials

Frontmatter

1. Introduction

Abstract

Dispersed organic systems are ubiquitous in nature. Wood consisting of lignin and cellulose is a well-known example. A natural dispersion is blood that consists of plasma and dispersed organic cells. The main ingredient of the plasma is water and, therefore, its flow behavior is Newtonian. The organic cells of various shapes and compositions are distributed in the plasma and significantly influence the flow properties of blood.

Helmut Münstedt

2. General Rheological Features of Polymeric Materials

Abstract

During processing, polymeric materials can be exposed to various types of deformation. Shear is prevalent in tube flow, for example, while elongation occurs whenever a fluid passes through narrowing ducts. The stresses and strain rates applied during processing can cover a wide range and, therefore, material functions are important for a great number of polymer based systems.

Helmut Münstedt

3. Characteristic Properties of Particles

Abstract

A great variety of fillers are used in polymeric materials of different kinds. The particles are distinguished by chemical composition, consistency, surface properties, shape, and geometrical dimensions. For spherical particles the diameter and their size distribution are important parameters, nonspherical particles are often characterized by the length related to the diameter, the so-called aspect ratio, for example.

Helmut Münstedt

4. Rheological Properties of Newtonian Polymeric Materials Filled with Microparticles

Abstract

The number of possible particle-filled systems is nearly unlimited. To each fluid, particles of various composition, size, distribution, shape, and concentration can be added that have an influence on flow properties. Therefore, general aspects are discussed in the following that may be the basis to understand the flow behavior of a special particle-filled material.

Michael Schmidt

5. Rheological Properties of Polymeric Materials Filled with Nanoparticles

Abstract

The Newtonian polymeric matrices used in Chapter 4 for the investigations on microparticles are particularly suitable if structures built up by particles and their interactions are studied. The influence of stress on rheological properties of filled systems, for example, can be related to changes in particle structure because the viscosity of the matrix remains constant and its elasticity is negligibly small.

Christian Triebel

6. Rheological Properties of Thermoplastic Materials with Carbon Fillers

Abstract

Carbon fillers used in polymeric composites are carbon black, graphite, carbon nanotubes and carbon fibers. The fillers with the greatest economic importance are carbon black and carbon fibers. They are industrially produced with a wide variety of properties. Graphite is a mined natural product and, therefore, not as well specified as the two others.

Helmut Münstedt

7. Rheological Properties of Filled Thermoplastics with Respect to Applications

Abstract

In practice, filled polymeric materials play an important role. Because some fillers are distinctly cheaper than the polymer matrix, in some cases they are added only to reduce material costs. However, material properties are changed in some way or the other by fillers. Thus, fillers can be used to improve the performance of a polymeric material or even generate characteristics not inherent to the matrix.

Helmut Münstedt

8. Elongational Properties of Filled Thermoplastics

Abstract

As shown in the previous chapters, the rheological properties of filled polymeric materials in shear can markedly differ from those of their matrices. These results provoke the question in what way the elongational behavior of thermoplastics is affected by various fillers.

Helmut Münstedt

9. Rheological Behavior of Polymer Melts with Intrinsic Structural Heterogeneities

Abstract

It is commonly assumed that amorphous polymers do not contain any structural heterogeneities built up by the molecules neither in the solid state nor in the melt. Semicrystalline polymers are distinguished by a great variety of ordered molecular structures that decisively determine mechanical properties.

Helmut Münstedt

10. Appendix Related to Particle-Filled Samples

Abstract

The PMMA/silica samples were prepared in solution. First, 15 wt.% of the dried polymer was dissolved in dichloroethane (DCE), and then different amounts of the carefully desiccated silica powder were added. DCE was found to provide the best dispersion of the particles. After the treatment with a high-speed stirrer for a few minutes, the solution was treated with ultrasound for 30 min.

Helmut Münstedt

11. Introduction to Polymer Blends

Abstract

Polymer blends are distinguished from the particle-filled polymeric materials presented in the foregoing chapters by the physical properties of the minor component. In the case of filled polymers, the matrix is a polymeric material to which solid particles are added that are not deformable in the temperature ranges applied.

Helmut Münstedt

12. Determination of Miscibility of Polymer Blends

Abstract

In spite of the low mixing entropy of polymer molecules, there are quite a number of miscible or partly miscible blends among the conceivable combinations of polymeric components. A list of such materials is given, for example, in [12.1]. Most of the polymer blends used in practice are immiscible, however. A miscible blend of relevance for applications is based on polystyrene (PS) and polyphenylene ether (PPE).

Helmut Münstedt

13. Rheological Properties of Blends of Homologous Polymeric Materials

Abstract

Blends from homologous polymers should be miscible, particularly when the molecular architecture is the same. Polystyrenes and polyethylenes are available with a wide variety of molecular structures. Therefore, they are very suitable for fundamental investigations on the rheological properties of homologous blends. Furthermore, blends of polystyrenes and blends of polyethylenes are widely used in many applications.

Helmut Münstedt

14. Rheological Properties of Polymeric Materials Filled with Rubbery Particles

Abstract

Immiscible polymer blends are distinguished from other heterogeneous polymeric systems by the specification that the two components are of macromolecular origin and, therefore, in contrast to solid fillers, they are deformable in a way similar to the matrix. Under certain conditions, the different phases are able to deform or even to flow, and subsequently the morphology of a blend may change.

Helmut Münstedt

15. Rheological Properties of Immiscible Polymer Blends

Abstract

The polymer blends as discussed in this chapter consist of immiscible polymeric components that are viscoelastic in their molten state. That means the components and the blends as well exhibit viscous and elastic properties. Moreover, the third characteristic property to be taken into account is the interfacial tension between the different phases that contributes to the elasticity.

Helmut Münstedt

16. Rheological Behavior of Compatibilized Blends

Abstract

Immiscible blends have the disadvantage that interactions between the matrix and the dispersed phase are weak and, therefore, optimal use of the synergisms of the components cannot be made. The exploitation of synergisms is particularly important in the case of mechanical properties. Furthermore, a coarsening of the morphology by the coalescence of droplets is unfavorable for many applications of blends.

Helmut Münstedt

17. Morphology Development of Immiscible Blends

Abstract

Besides the rheological behavior of polymer blends discussed in the previous chapters, mechanical properties, for example, are decisively determined by morphological features. As shown before, the chemical nature of the blend components and their ratio have a great influence on morphology. But even if the composition is fixed, processing is an important factor for the final morphology of a manufactured item.

Marcus Heindl, Zdenek Stary

18. Morphology Development in Compatibilized Polymer Blends

Abstract

Due to the importance polymer blends have today, a wide range of materials and processes exists that are used to tailor and improve blend properties. For these developments, so-called compatibilization plays an important role in improving the adhesion of dispersed phase and matrix and, following from that, the properties of a blend.

Zdenek Stary

19. Appendix Related to Polymer Blends

Abstract

Knowledge about the thermal stability of a polymer melt is important for an assessment of the processing behavior. Furthermore, from the change of rheological properties due to aging, qualitative conclusions with respect to alterations of the molecular or morphological structure of a polymeric material can be drawn.

Helmut Münstedt

20. About the Author

Abstract

Prof. Dr. Helmut Münstedt is a retired professor of the Friedrich-Alexander-University Erlangen-Nuremberg. From 1993 to 2009 he was in charge of the Institute of Polymer Materials at the Department of Materials Science and Engineering. His research was centered on the properties of polymeric materials in a wide field, from medical applications to processing. Fundamental work has been performed on the influence of molecular structure on the many facets of the rheological behavior.

Helmut Münstedt

Backmatter