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2014 | Buch

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In-situ Structure Characterization of Elastomers during Deformation and Fracture

verfasst von: Karsten Brüning

Verlag: Springer International Publishing

Buchreihe : Springer Theses

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

This thesis offers novel insights into the time-dependent structural evolution of polymers under deformation. In-situ tensile experiments at high-brilliance synchrotron sources allowed to characterize the material with unrivaled resolution in time and space. The strain-induced crystallization in natural rubber was studied by wide-angle X-ray diffraction. Special emphasis was put on the establishment of new structure-property relationships to give a more in-depth understanding of the mechanical performance of rubber parts, e.g. in tear fatigue loading. To this end, the kinetics of strain-induced crystallization were investigated, subjecting the material to high strain rates. The local structure around a crack tip was observed by scanning wide-angle X-ray diffraction. Ultra-small angle X-ray scattering served to study filled elastomers under deformation, from specially prepared model filler systems to industrially relevant carbon black filled rubbers. Other methods include electron microscopy coupled with in-situ tensile testing and optical dilatometry to examine cavitation in rubbers.

The underlying theory as well as a literature review are covered by an extensive introductory chapter, followed by a description of the experimental techniques. The results are presented in more detail than in the original journal publications.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

This chapter introduces the reader to the fields of research covered by this thesis and gives an overview of rubber materials, rubber processing, rubber reinforcement, X-ray scattering and diffraction, strain-induced crystallization, and cavitation in natural rubber. The chapter aims to provide the required background for the reading of this thesis to non-experts, but is also of interest to the experienced researcher, giving a broad literature review, citing more than 200 literature references.

Karsten Brüning

Chapter 2. Motivation and Objectives

Abstract

This chapter puts the current work in the context of the past research performed in the fields of rubber reinforcement by strain-induced crystallization and filler reinforcement. It derives the motivation from recent experimental progress in synchrotron radiation sources, enabling novel experiments, which in turn can establish new structure-property relationships, ultimately helping to improve theoretical approaches in modeling the mechanical behavior of rubbers.

Karsten Brüning

Chapter 3. Experimental

Abstract

This chapter provides a detailed description of the experiments performed in this work. It starts with a section on the material preparation. The major part deals with the synchrotron scattering setups, which were used in wide or small angle transmission geometry, coupled with various tensile testing machines. The computer processing of the scattering data to extract quantities like the degree of crystallinity, orientation, cavitation volume is described. Additional methods, e.g., mechanical testing, optical dilatometry, and in-situ tensile testing in a scanning electron microscope are covered.

Karsten Brüning

Chapter 4. Results

Abstract

This chapter presents the major findings of the thesis. The results are presented in greater detail than in the original journal publications. The chapter includes crystallization under quasistatic tension, strain amplification in filled rubbers, and crack tip scans under static as well as dynamic conditions. A special emphasis is put on the kinetics of the strain-induced crystallization in natural rubber, obtained by strain-jump experiments, resolving the crystallization kinetics at unrivalled timescales in the millisecond range. The finite kinetics are reflected in the crystallization under dynamic cyclic load and are shown to affect the mechanical and tearing performance of rubbers at high frequencies, which usually occur in tires. A novel approach is used to quantify the filler orientation under strain, using WAXD and USAXS, coupled with an analytical model. SEM observations of local processes in the crack propagation zone with unprecedented magnification are presented and given new insight into the deformation mechanisms on the ?m-scale.

Karsten Brüning

Chapter 5. Conclusion and Outlook

Abstract

This chapter summarizes the outcomes of the thesis and highlights the major results.

Karsten Brüning

Backmatter

Titel: In-situ Structure Characterization of Elastomers during Deformation and Fracture
verfasst von: Karsten Brüning
Verlag: Springer International Publishing
Electronic ISBN: 978-3-319-06907-4
Print ISBN: 978-3-319-06906-7
DOI: https://doi.org/10.1007/978-3-319-06907-4

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