Abbreviations and denotations xi
1 Polymer restructuring at plastic deformation 1
1.1 Terminology 1
1.2 Classical concepts of polymers deformation 8
1.3 Mechanism of crazing in liquids 10
1.4 Collapse of crazes structure 13
1.5 Applied aspects of crazing 18
2 Modification of synthetic fibers 23
2.1 Overview of synthetic fibers 24
2.2 Specifics of polyester fibers crazing 28
2.3 Techniques for synthetic fibers modification by crazing mechanism 31
2.4 Development of modification technique 43
3 Antimicrobial fibers 51
3.1 Problem of textile fabrics biodeterioration 51
3.2 Fibers with antimicrobial properties 53
3.3 Antiseptic components of fibers 55
3.4 Modifying compounds based on triclosan 59
3.5 Modifying compounds containing silver 62
3.6 Antimicrobial activity of fibers 66
3.7 Antimicrobial fibers’ use in medicine and clothing 71
4 Fibers of reduced combustibility 81
4.1 Fire-retardants 81
4.2 Fire-retardants for PET fibers modification 87
4.3 Estimation of fibers combustibility 91
4.4 Specifics of production and properties of fibers
of reduced combustibility 93
5 Aromatized and repellent fibers 99
5.1 Aromatic agents for textile materials 99
5.2 Modifying compounds with the smell of lavender 101
5.3 Manufacturing and testing of aromatized fibers 104
5.4 Repellent fibers, their range and application 106
6 Fibers for securities protection from counterfeit 115
6.1 Methods of securities protection from counterfeit 115
6.2 Paper filling with threads and fibers 120
6.3 Luminescent colorants for fibers 121
6.4 Requirements to fibers and methods for their production 122
6.5 Discontinuous dyeing of fibers 125
6.6 Luminescence of dyed fibers 129
6.7 Introduction of ferromagnetic indicators 134
7 Novel crazing technology applications 139
7.1 Radioabsorbing fibers 139
7.2 Electroconductive fibers 144
7.3 Investigation of the possibility of bicomponent and superthin PET fibers modification 147
Since ancient times, the mankind uses fibrous materials for production of clothes, tools, as well as for medical purposes. For example, the use of fibers in medicine was first mentioned in Surgical Papyrus, nearly 4000 years ago. In the Indian manuscript Susanta Sambita, written approximately 2500 years ago, a variety of fibrous materials are mentioned such as horse hair, leather strips, cotton, animal sinews, and fibrous tree bark. At present, textiles have found their way into a variety of medical applications. In addition to protective medical clothing, textiles in the form of fibers and fabrics are used as implants, filters, and surgical dressings. Recent decades have witnessed major development in the production of medical textiles, as well as in materials and technologies used to manufacture them.
The global problem of technogenic deterioration of environmental conditions for life on Earth have been considerably aggravated in the 21st century. The problems of local reduction of detrimental effects of the changed environment on human beings and the sphere of their existence have become topical as never before.
In the system “human—textile product—habitat,” the textiles act as protection for a person. The new generation textile products which are produced taking into account the adverse changes in the ecological environment are actively minimizing their effect. Additional functional properties are being imparted to polyester fibers which are traditionally incorporated into the composition of practically all textile fabrics to increase their wear- and crease-resistance. The best world samples of polyester fibers possess antimicrobial activity and an ability to discharge static electricity, demonstrate the reduced combustibility, and have other special properties. American, Chinese, Japanese, and other textile products have appeared in the market which react “smartly” to the change in environmental parameters, reducing its harmful effects on a human being. Targetedly modified polyester fibers are an indispensable component of such products.
Chemical fibers are obtained from products of chemical processing of natural polymers (artificial fibers) or from synthetic polymers (synthetic fibers). Despite continuous improvement of the textile production and advancement in technologies for chemical fibers, not many methods to impart them with special properties are developed. Classical methods for filling and plasticization of the polymer base have long remained a sole instrument to regulate the chemical fiber properties. Currently, the targeted modification of the surface layer of fibers which does not affect their core has become the leading trend in the textile materials science. Such modification is implemented predominantly by the diffusion mechanism using the technological environments which are thermodynamically compatible with the polymer base of the fibers. The latter condition is a significant limitation to the range of technological impact on the structure of the surface layer, thus making it impossible to introduce a lot of very effective target modifiers into it.
As an alternative, production of multilayer fibers consisting of polymer core (which properties essentially determine the deformation-strength characteristics of the fiber) and one-two external layers which impart the fiber with special properties (wettability/ nonwettability, frictionality/antifrictionality, high fusibility/low fusibility, etc.) has experienced active growth in many countries in the 1990s. However, interest in them quickly faded due to high costs of the considerably sophisticated industrial equipment, low stability of technological process of extrusion “facing” of the fibers, unreliability of multitubular extrusion heads and complexity of their repair.
The situation was radically changed at the introduction of the methodology of surface modification of chemical fibers based on implementation of the crazing phenomenon. Crazing is a process of plastic deformation of polymers which brings them into a specific structural state. At loading levels and properties of the environment (which are individual for each material), special areas of the oriented state—crazes— occur in the specimen. These are microcracks which walls are connected by fibrils less than 10 nm in diameter. Crazing was first discovered and studied by the American physicist- chemists E.I. Kramer, R.P. Кambour, A.S. Argon, and M.M. Salama; their first publications on crazing were issued in the early 1970s. The extent of crazes opening in the polyester fibers (in glassy state at room temperature) subjected to orientational drawing in the surface-active liquid media which promote cracking of fibers provides for the possibility to introduce into the surface layer of the fiber any substances, irrespective of their physico-chemical nature.
The extremely slow (months, years) release of the nonvolatile substances captured in the crazes to the environment which was discovered by Russian scientists N.F. Bakeev and A.L. Volynskii is of equal practical interest. At first, crazing was used in the processes of water-repellent fibers dyeing, and in the 1980s–1990s to produce semiconductor and low-combustible chemical fibers.
Nevertheless, crazing has not found application yet in large-scale production of chemical fibers and is very seldom used in the technology for their processing. As a rule, basic methods for chemical fibers modification by the mechanism of crazing are the know-how of the leading manufacturers of fibers with special properties which are closed to third-party experts.
This book summarizes the data available in scientific and patent literature on physico- chemical nature of crazing and discusses the results of original researches performed by the authors on implementation of this phenomenon at drawing the synthetic fibers which resulted in development of new technologies to produce multifunctional fibers.
The research findings presented in this monograph are obtained with financial support from the scientific and technical program “Composite” of the Union State of Russia and Belarus and are complemented with the results of activities performed under the contract with UNIKO Chemical Co., Ltd (South Korea) and the researches conducted by an order of the state program of scientific researches “Functional Materials” of the National Academy of Sciences of Belarus.
The authors would like to express their gratitude to Sergey Zotov, Elena Klimovich, and Tatyana and Konstantin Ovchinnikov, employees of the Metal-Polymer Research.
Institute of National Academy of Sciences of Belarus, for their creative participation in carrying out the experiments, including the ones on the industrial equipment, the results of which are presented in the book. We dedicate this book to the memory of our untimely deceased friend, colleague, and teacher, Professor Leonid Pinchuk, whose ideas are implemented in a number of our joint publications and inventions.
Victor A. Goldade and Nataly S. Vinidiktova