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The series Advances in Polymer Science presents critical reviews of the present and future trends in polymer and biopolymer science. It covers all areas of research in polymer and biopolymer science including chemistry, physical chemistry, physics, material science. The thematic volumes are addressed to scientists, whether at universities or in industry, who wish to keep abreast of the important advances in the covered topics.Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.Review articles for the individual volumes are invited by the volume editors. Single contributions can be specially commissioned.Readership: Polymer scientists, or& nbsp;scientists in related fields interested in polymer and biopolymer science, at universities or in industry, graduate students.

Inhaltsverzeichnis

Frontmatter

The Extended Non-affine Tube Model for Crosslinked Polymer Networks: Physical Basics, Implementation, and Application to Thermomechanical Finite Element Analyses

Abstract
This chapter is devoted to a summary of the so-called extended non-affine tube model. First, general model approaches for representation of the behavior of elastomers within numerical simulations are discussed. Second, the extended non-affine tube model is considered in the context of hyperelastic material models. Starting from molecular-statistical considerations, a Helmholtz free energy function is derived and formulated in terms of continuum mechanical quantities of the macroscale. Furthermore, combination with a model approach to represent continuum damage and time-dependent effects is addressed. The free energy function of the model approach is further set into the context of thermomechanics to account for temperature-dependent behavior of elastomers within numerical simulations. Finally, finite element implementation of the extended non-affine tube model and its application to uniaxial and biaxial tension tests performed on elastomer specimens are presented.
Ronny Behnke, Michael Kaliske

Reinforcement of Rubber and Filler Network Dynamics at Small Strains

Abstract
Carbon black particulate reinforcement of rubber is examined in terms of linear viscoelasticity and the dynamics of the filler particle network. First, it is demonstrated that for the case of purely hydrodynamic reinforcement, the dynamics of the filled rubber are equivalent to those of the corresponding unfilled material. A breakdown in thermorheological simplicity is observed with the onset of filler networking in reinforced compounds. The dynamics of the filler network are initially examined by strain sweep/recovery experiments performed on uncrosslinked materials. The role of the surface activity of carbon black in defining the rate and magnitude of flocculation is explored and various models to describe this process are reviewed. The dynamics of carbon black filler networks in crosslinked materials are probed using small strain torsional creep experiments. Physical ageing (structural relaxation) of filled compounds at temperatures well above the glass transition temperature of the rubber matrix is observed and the ageing rate is found to scale with the level of filler networking in the various compounds. Physical ageing is the result of non-equilibrium, slow dynamics, which sheds light on the physical origin of the filler network. Furthermore, the implications of physical ageing of highly filled rubbers on typical linear viscoelastic time–temperature superposition experiments are discussed.
Lewis B. Tunnicliffe, James J. C. Busfield

Multiscale Contact Mechanics with Application to Seals and Rubber Friction on Dry and Lubricated Surfaces

Abstract
Fluid leakage out of mechanical equipment such as gearboxes, hydraulic systems, or fuel tanks could cause serious problems and thus should be avoided. Seals are extremely useful devices for preventing such fluid leakages. We have developed a theoretical approach for calculation of the leak rate of stationary rubber seals and the friction force for dynamic seals. The theory is based on a recently developed theory of contact mechanics, which we briefly review. To test the theory, we have performed both simple model experiments and experiments on engineering seal systems. We have found good agreement between the calculated and measured results, and hence our theory has the potential to improve the future design of efficient seals.
We briefly review the processes that determine rubber friction on lubricated smooth and rough substrate surfaces. We present experimental friction results for lubricated surfaces, obtained using a simple Leonardo da Vinci setup. The data is analyzed using the Persson rubber friction and contact mechanics theory.
B. N. J. Persson, B. Lorenz, M. Shimizu, M. Koishi

Multiscale Modeling Approach to Dynamic-Mechanical Behavior of Elastomer Nanocomposites

Abstract
Rubber composites based on an elastomeric matrix filled with rigid fillers such as carbon black or silica remain important materials for technical applications and everyday life. Targeted improvement of the mechanical properties of these materials requires a deep understanding of the molecular mobility over broad time and temperature scales. We focus here on recent studies of the dynamic properties of rubber composites with the aid of a physically motivated multiscale theoretical approach. Rubber compounds, based on a solution-polymerized styrene butadiene rubber filled with precipitated silica, have been investigated. The construction of master curves for the storage and loss moduli over more than 15 decades of frequencies is presented. The master curves over the whole frequency range are analyzed with the aid of a new multiscale approach, which includes contributions from the relaxation processes described in rigorous theoretical studies for different scales of motion. It takes into account the long-scale motions of dangling chain ends, Rouse-like dynamics and bending motions of semiflexible chain fragments in the intermediate frequency range, and the specific nonpolymeric relaxation at very high frequencies. The modification of molecular mobility of polymer chains on the surfaces of filler particles and the contribution of the percolation network built by the filler are discussed. The proposed theoretical approach allows fitting of the dynamic moduli of filled and unfilled rubbers in the linear viscoelastic regime with a limited set of parameters (relaxation times, scaling exponents, molar mass of the Kuhn segment, etc.) having reasonable values. The slowing down of the relaxation processes in the vicinity of the filler particles is demonstrated.
Ievgeniia Ivaneiko, Vladimir Toshchevikov, Stephan Westermann, Marina Saphiannikova

Networks: From Rubbers to Food

Abstract
Many soft materials can be viewed as networks of different structure and complexity. Their (statistical) physics determine their elastic deformation behavior, fracture, and failure. In food systems, similar properties are of importance. This contribution discusses some of the common points between elastic materials and food gels. Topics range from fundamental physics to some applications in materials science and food science.
B. I. Zielbauer, N. Schönmehl, N. Chatti, T. A. Vilgis

Nanostructured Ionomeric Elastomers

Abstract
Driven by the desire to find an alternative way of vulcanizing elastomers without sulfur, researchers have widely explored ionic crosslinking techniques. The opportunity was taken to play with the functionality of the host polymer and its modification process to develop nanostructured ionic elastomers. Neutralization of polar elastomers by various divalent metal cations has been the route most employed for fabrication of this class of material. Ionic association or aggregation on the molecular level results in microphase separation of certain regions and, hence, enables easier processing. Thermally labile ionic domains introduced into the network make the entire material thermoresponsive and, therefore, it is possible to obtain reversible transition of dynamic mechanical properties. The unique network structure of these materials has led to outstanding physical properties that have not been achieved so far for conventional sulfidic networks. Consequently, many multifunctional and smart materials have been envisaged and designed using these systems. A detailed overview is provided on the various nanostructured ionic elastomers developed over the years. It would not be exaggerating to mention in the context of the discussion that nanostructured ionic elastomers will definitely open up new horizons in materials research.
Debdipta Basu, Amit Das, Klaus Werner Stöckelhuber, Sven Wießner

Graphene-Based Elastomer Nanocomposites: Functionalization Techniques, Morphology, and Physical Properties

Abstract
Understanding the fundamentals involved in the fabrication of an elastomer nanocomposite is crucial for the development of high performance materials. Despite a plethora of studies of different types of elastomer nanocomposites, work related to the development of graphene-based elastomer nanocomposites has only gained precedence in recent years. Because the inherent structure of graphene often limits its processability inside a high molecular weight elastomer matrix, various strategies have been adopted to control the dispersion of graphene in an elastomer. In this chapter, representative and commercially important elastomers are selected for discussion. The effect of different processing routes for the preparation of elastomer/graphene nanocomposites and their correlation with dispersion of the graphene-based filler in the elastomer matrix are discussed in detail. Parameters controlling strength, thermal stability, barrier properties, and dielectric behavior are discussed. This chapter gives a comprehensive review of the preparation of graphene/elastomer nanocomposites and also provides an idea of the structure–property relationships that exist for such nanocomposites.
Titash Mondal, Anil K. Bhowmick, Ranjan Ghosal, Rabindra Mukhopadhyay

Characterization and Application of Graphene Nanoplatelets in Elastomers

Abstract
The physical performance of elastomer composites based on graphene nanoplatelets (GNPs) was investigated regarding the mechanical and fracture mechanical properties, viscoelastic and dielectric responses, and friction, wear and gas permeation properties. Static gas-adsorption measurements at very low pressures demonstrated that pronounced differences in the surface activity and specific surface area can be observed for different GNPs. The surface activity was shown to be large for GNPs that indicate strong polymer–filler couplings for these systems. This is closely related to the energetic heterogeneity (i.e., the number of highly energetic sites) at the filler surface, which determines the polymer–filler interaction strength and is the main factor determining the reinforcing potential. Based on this information, the stress–strain responses of several GNP types and fine graphite were analyzed in styrene butadiene rubber (SBR) and nitrile butadiene rubber (NBR) with and without softener in relation to standard carbon black. Results demonstrated qualitatively different mechanical behaviors. It was revealed that the mechanical response of the composites under quasistatic cyclic loading can be well understood on the basis of quantitative analysis using a micromechanical model. Gas permeation is strongly reduced by GNPs and further reduced in anisotropic samples with orientation of GNPs perpendicular to the gas flow direction. In comparison with carbon black, dynamic crack growth under pulsed excitation remains almost unaltered for all GNP types, although the wear behavior under sharp abrading conditions is worse. The dry and wet friction properties of SBR composites are well described by hysteresis and adhesion friction theory for GNPs and for carbon black. The dry friction coefficient on rough granite and especially on smooth glass decreases significantly when GNPs are used instead of carbon black. However, the wet friction coefficient on rough granite increases slightly at small sliding velocities, which correlates with the higher hysteresis of GNP composites in the rubbery plateau region.
M. Klüppel, M. M. Möwes, A. Lang, J. Plagge, M. Wunde, F. Fleck, C. W. Karl

Tearing Energy as Fracture Mechanical Quantity for Elastomers

Abstract
The fracture mechanical characterization of elastomeric materials is based on a global energy balance. Tearing energy was introduced in 1953 by Rivlin and Thomas to characterize the energy required for an infinitesimal increase in surface area during crack propagation. Enhancing the contributions of various energy dissipation mechanisms during the process of crack propagation is crucial for the understanding and modification of elastomeric materials with respect to an enhanced service life. Apart from the tearing energy, alternative fracture mechanical quantities based on the global energy balance are reviewed and discussed with respect to various influencing factors such as geometrical constraints of the specimen, specific loading conditions, and the specific material and its structural details. Finally, the application of advanced experimental methods characterizing the stages of crack initiation, propagation, and wear under more practical loading conditions are reviewed.
Radek Stoček, Thomas Horst, Katrin Reincke

Backmatter

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