**Meet the editor**

Anna Boczkowska is an assistant professor at the Faculty of Materials Science and Engineering, Warsaw University of Technology. She graduated from the Faculty of Materials Science and Engineering in 1989. She received her PhD degree in 2000 and D.Sc degree in 2011. Her scientific interest is mostly related to the processing and study of polymer materials, especially magnetorheologi-

cal elastomers , polymer matrix composites and nanocomposites. Dr Anna Boczkowska has industrial background of 20 years in the development and application of urethane elastomers and composite materials. She is an author of over 100 scientific papers and 4 books. She is a member of the American Chemical Society, American Association for the Advancement of Science, International Society of Optical Engineering and many others.

## Contents

#### **Preface** XI



X Contents


Chapter 15 **The Significance of Equi-Biaxial Bubble Inflation in Determining Elastomeric Fatigue Properties 363**  Steve Jerrams, Niall Murphy and John Hanley

## Preface

Elastomers due to their versatile properties have been widely explored in academic and industry since they were invented in the nineteen century. By definition, elastomer is a polymer with viscoelasticity, having low Young's modulus and high yield strain in comparison to other materials. The term "elastomer" is derived from "elastic polymer". The elasticity is caused by the ability of the long chains (macromolecules) to reconfigure themselves to distribute an applied stress. Elastomers are amorphous polymers used above their glass transition temperature, so that significant motion of macromolecule's segments is possible. The chemical (covalent) or physical (hydrogen) cross-linkages ensure that the elastomer returns to its original shape after deformation, when the stress is removed. As a result of this extreme flexibility, elastomers can reversibly extend from a few up to one hundred percent or even more, dependently on their chemical and physical structure. Elastomers can be thermoplastics or thermosets if the segments of macromolecules are cross-linked during curing. They are commonly used in a large range of industrial and household applications, however, the progress in development of new methods of synthesis and characterisation, new materials, especially "smart" and nanocomposites based on elastomer matrix is still up-to-date.

This book provides an extensive overview of current trends in the area of elastomers and their composites from the chapters contributed by internationally recognized specialists. The book deals with novel synthesis, modelling and experimental methods in elastomers and provides a unique opportunity to discover the latest research on elastomer advances from laboratories around the world. Numerous references are given at the end of each chapter to enable the reader to explore the topics covered in greater detail.

The book has a broad scope and brings together 7 Chapters that deal with the various aspects of processing, as well as experimental and analytical approaches to elastomer characterisation. Each section demonstrates how enhancements in materials, processes and characterization techniques can improve performance in the field of engineering.

Chapter 1 presents new approach to crosslinking of elastomers by means of electron beam. Usually elastomers show low thermal conductivity, and therefore, require complex and high cost heating methods; thus, the ionizing (accelerated electrons)

#### XII Preface

method shows high interest for the grafting and cross-linking processes. In addition to the lack of environmental impact, reliability, flexibility and low costs render the radiation technologies especially attractive.

Chapter 2 contains the overview on liquid crystal elastomers, which combines the properties of liquid crystals order characteristic with the elasticity typical for the conventional rubbers, as they are today being considered as promising candidates for media that can easily be driven by external stimuli (heat, electromagnetic or optic field) for applications such as data storage, image processing, or optical modulators.

Chapter 3 discusses structure, rheological and vulcanization properties of elastomer based nanocomposites and presents the remarkable improvements of mechanical and barrier properties of a rubber matrix, obtained due to addition of clays or hybrid pigments, that led to their application in tire and sport goods. Mechanical properties, spectrophotometric and DSC data of the vulcanizates produced with the composite pigment fillers are also reported before and after being aged under UV radiation.

Chapter 4 provides information about smart materials such as magnetorheological elastomers and thermo-shrinkable-elastomers. The overview on magnetorheological elastomers is given, as well as basic knowledge about rheology and magnetorhelogy. The effect of the amount, size and orientation of the particles on their microstructure and properties is discussed. Also in this chapter the crosslink density, the static and dynamic mechanical properties and the thermo-shrinkable behaviour of vulcanisates is described. The effect of the ionic crosslink content on the ability of the vulcanisates to recover their primary shape upon thermal treatment is discussed.

Chapter 5 reviews the recent research advances in the emerging field of elastomeric electronics. Various strategies in implementing electronic devices and systems that can be flexed, twisted, and compressed are addressed, with special emphasis on stretchable microfluidic electronics. The recently demonstrated elastomeric electronic devices, e.g. foldable and stretchable antennas, radiation sensors, as well as wireless strain sensors, using the microfluidic approach, are presented and analyzed in detail. Examples of elastomers used in microelectronics and microfluidics are shown, as well as elastomer based composites with conductive particles as a filler. Future perspectives and outlook for elastomeric electronics are discussed.

Chapter 6 aims at expounding properties, application and performance of natural rubber latex (NRL) as a modifier in cement concrete and mortar. Properties of NRL influencing performance in mechanical and durability functions are discussed. Also influence of high temperature on concrete strength and durability is shown. Recent trends in research activities and challenges facing applications of elastomers are provided.

In Chapter 7 the development of experimental testing and various analytical, as well as FEM models for characterising of elastomer microstructure and properties are presented.

This book addresses to industrial and academic researchers in the fields of physical, chemical, biological sciences and engineering. It is intended to be useful not only for to engineers, academics, researchers and designers in the field of materials sciences, but also to postgraduate research students and manufacturers of elastomer's products.

X Preface

radiation technologies especially attractive.

method shows high interest for the grafting and cross-linking processes. In addition to the lack of environmental impact, reliability, flexibility and low costs render the

Chapter 2 contains the overview on liquid crystal elastomers, which combines the properties of liquid crystals order characteristic with the elasticity typical for the conventional rubbers, as they are today being considered as promising candidates for media that can easily be driven by external stimuli (heat, electromagnetic or optic field) for applications such as data storage, image processing, or optical modulators.

Chapter 3 discusses structure, rheological and vulcanization properties of elastomer based nanocomposites and presents the remarkable improvements of mechanical and barrier properties of a rubber matrix, obtained due to addition of clays or hybrid pigments, that led to their application in tire and sport goods. Mechanical properties, spectrophotometric and DSC data of the vulcanizates produced with the composite pigment fillers are also reported before and after being aged under UV radiation.

Chapter 4 provides information about smart materials such as magnetorheological elastomers and thermo-shrinkable-elastomers. The overview on magnetorheological elastomers is given, as well as basic knowledge about rheology and magnetorhelogy. The effect of the amount, size and orientation of the particles on their microstructure and properties is discussed. Also in this chapter the crosslink density, the static and dynamic mechanical properties and the thermo-shrinkable behaviour of vulcanisates is described. The effect of the ionic crosslink content on the ability of the vulcanisates

Chapter 5 reviews the recent research advances in the emerging field of elastomeric electronics. Various strategies in implementing electronic devices and systems that can be flexed, twisted, and compressed are addressed, with special emphasis on stretchable microfluidic electronics. The recently demonstrated elastomeric electronic devices, e.g. foldable and stretchable antennas, radiation sensors, as well as wireless strain sensors, using the microfluidic approach, are presented and analyzed in detail. Examples of elastomers used in microelectronics and microfluidics are shown, as well as elastomer based composites with conductive particles as a filler. Future perspectives

Chapter 6 aims at expounding properties, application and performance of natural rubber latex (NRL) as a modifier in cement concrete and mortar. Properties of NRL influencing performance in mechanical and durability functions are discussed. Also influence of high temperature on concrete strength and durability is shown. Recent trends in research activities and challenges facing applications of elastomers are

In Chapter 7 the development of experimental testing and various analytical, as well as FEM models for characterising of elastomer microstructure and properties are

to recover their primary shape upon thermal treatment is discussed.

and outlook for elastomeric electronics are discussed.

provided.

presented.

**Anna Boczkowska**  Warsaw University of Technology, Faculty of Materials Science & Engineering, Warsaw, Poland

**New Approach to Elastomer Crosslinking** 

**Chapter 1** 
