Photodegradation and light stabilization are very important aspects of polymer aging. Polymer degradation includes different types of processes: thermodegradation, oxidation, acting of ozone, photodegradation, radiation, hydrolysis, mechanical degradation, and biodegradation. It is very important to know the mechanism of polymer degradation in order to select stabilizers against the degradation. This volume presents the analysis of achievements in the field of photodegradation of polymers. It includes, first of all, data of Russian investigators who have decisively contributed in the development of this field of knowledge (the schools headed by academicians V.V. Korshak, N.M. Emanuel, N.S. Enikolopov, A.A. Berlin, and many others).

An advanced, student-centered textbook that uses popular media to explore diverse perspectives from across Russian-speaking cultures Pro-dvizhenie is a student-centered, inquiry-based textbook designed to build Advanced-level Russian proficiency through engagement with timely topics that encourage reflection and examination. Whether exploring the role of technology in relationships, learning about indigenous communities of Russia, or reflecting on what it means to live well, Pro-dvizhenie uses popular Russian film, TV, and media as a springboard for various types of activities, including skill-building exercises, essay writing, and group projects. Students are encouraged to challenge assumptions and make intercultural connections throughout while developing ACTFL Advanced-level skills such as argumentation, narration, and collaboration. Students benefit from extensive activities and resources, including audio and video of diverse voices and viewpoints from across Russia, available to stream on the Press website. A full-service textbook for instructors, Pro-dvizhenie includes extensive online instructors' resources, such as additional grammar and vocabulary assignments, writing and group project prompts, grading rubrics, and answer keys. A modular structure and activities at various levels of difficulty give instructors the flexibility to select material in the book based on their class's needs, making Pro-dvizhenie perfectly suited for mixed-level classrooms. The textbook can be used over one semester or over the course of a full year.

Photochemical reactions are the main class of chemical processes. These processes provide for life on Earth, since due to photochemical processes, plants absorb carbon oxide from the atmosphere changing them into the "meal" for all creatures on Earth. Together with "good" photochemical processes there are some "bad" as well. This book is about photodestruction and light stabilisation and is devoted to these processes. For example, the heterochain polymers. They are the main class of large-tonnage polymers, which are used for manning a great variety of polymer and composite materials (including nanocomposites).

The main goal of this book is to describe the synthesis and properties of low and high-molecular compounds on the quantitative level. Special attention was given to composition materials based on polymers and dispersed wood, the mechanism of HCL elimination reactions via a four-centre transition state during PVC thermal destruction, swelling of the filled polymer compositions, structure and properties of combined systems based on butadiene-nitrile and ternary ethylene-propylene elastomers, intensification mass transfer processes in fast liquid-phase chemical reactions, the examples of hetero-nanophase kinetic description of photochemical reactions, the nanometric particle-like local structures and their implications in polymer behaviour, fractal physical chemistry of polymer solutions, modification of polycyanurates by polyethers, polyesters and polyurethanes, hybrid and interpenetrating polymer networks. This collection includes articles devoted to production of polymers, polymeric mixtures, composite and filled polymers, questions of expanding lifetime of polymeric articles, biologically active substances, modification of polymers and polymer-analogous transformations, fractal physical chemistry of polymer solutions, the study of structural transformations in polymers and some other questions. Of special attention are also production of pure substances and protection of the environment.

Cellulose and its derivatives -- cellulose acetate -- are renewed polymers, that, together with the whole complex of valuable and indispensable properties, defines continuous growth of their production. Acetate fibres differ from cellulose fibres in light and thermooxidative stability, as the presence of ester groups decreases stability of molecular structure, owing to which destructive processes begin at much lower temperatures and weak energy effects. Since macromolecules of cellulose acetate are constructed on the basis of cellulose then mechanism of photodestruction of these polymers may be considered as general. The most important energetic factor, which photodestruction of cellulose and its derivatives depend on, is intensity of irradiation and wave length. Destruction of cellulose and its derivatives under atmospheric conditions, proceeding as a result of photochemical reaction, on the whole takes place under the action of ultraviolet rays with ?=200-360 nm. Since cellulose contains three types of chromophore groups -- hydroxyl, acetate and semiacetate and also aldehyde -- then it is considered that light absorption in the region of 250-300 nm is caused just by them. At the same time some authors, bringing the possibility of light absorption by acetal chromophore in question, have put forward the supposition that photochemically active centres in cellulose materials, containing carboxyl and hydroxyl groups, may be molecular complexes between these groups, connected by the system of hydrogen bounds with definite energy of interaction. Disproportion of intermolecular bonds, providing fixation of excited state in cellulose matrix takes place in such complexes at their excitation. Thus, there are many different hypotheses, often contradicting each other, about the effect of chromophore groups on light absorption by cellulose. There are many data about the nature of free-radical particles, being formed at irradiation of cellulose by ultraviolet light. Since, being formed products of phototransformation are highly mobile and easily undergo further transformations, method of electron-paramagnetic resonance (ESP) is one of the most effective for these particles identification. Critical analysis of a great number of works on EPR spectra interpretation is quite fully given in surveys. More than 20 different radicals are being formed at ultraviolet irradiation as a result of break of practically all bonds C-C; C-H; C-O. Main types of macroradicals, with indication of atom and groups of atoms after removal of which these macroradicals are formed, are presented in scheme 1. of this book.

Photodegradation and light stabilization are very important aspects of polymer aging. Polymer degradation includes different types of processes: thermodegradation, oxidation, acting of ozone, photodegradation, radiation, hydrolysis, mechanical degradation, and biodegradation. It is very important to know the mechanism of polymer degradation in order to select stabilizers against the degradation. This volume presents the analysis of achievements in the field of photodegradation of polymers. It includes, first of all, data of Russian investigators who have decisively contributed in the development of this field of knowledge (the schools headed by academicians V.V. Korshak, N.M. Emanuel, N.S. Enikolopov, A.A. Berlin, and many others).