Поглощение воды и водных растворов глинополимерными нанокомпозитами внедрения

Рассмотрено первичное и повторное поглощение воды и раствора, имитирующего жидкие отходы атомных станций, глинополимерными нанокомпозитами внедрения, синтезированными на основе бентонита. Показано, что частицы глинополимерного нанокомпозита более эффективно поглощают воду и солевые растворы по сравнению с частицами природного бентонита.Розглянуто первинне і повторне поглинання води і розчину, який імітує рідкі відходи атомних станцій, глинополімерними нанокомпозитами проникнення, синтезованими на основі бентоніту. Показано, що частинки глинополімерного нанокомпозита ефективніше поглинають воду і сольові розчини у порівнянні з частинками природного бентоніту.In many cases the use of nanocomposites is restrained by insufficient knowledge of their properties. It primarily relates to intercalated nanocomposites, especially the nano composites with particles size less than 0.6 mm, containing a significant amount of clay (>60 %). The research is focus on the study of the properties of such na nocomposites. The bentonite clay from the Cherkassy deposit comprising up to 95 % of Ca-montmorillonite was used for the synthesis of nanocomposites. The preliminary substitution of Na⁺ cations for Ca²⁺ and Mg²⁺ cations was carried out. The nanocomposites clay-polymer were obtained in the process of free radical polymerization. The nanocomposites, dried at 105 ºC with particle size of 0.4 ÷ 0.6 mm were used for experiments. The properties of the nanocomposites to take up water and solutions were studied by Enslin method. The maximum value of water uptake was 69.45 ml/g. Subsequently, the sample was dried on the filter to constant weight and repeated water uptake was examined. In this case, the result was 82 ml/g, i. e. in repeated contact with water particles absorbed by 18 % more amount water than during first water uptake. The increase in water uptake is due to nonuniform polymerization (in volume and time), which resulted in deformation of some polymer chains and only after water absorption, polymer chains have a chance to take a more low-energy position. Since this phenomenon was observed for particle size of less than 0.6 mm, it can be assumed that the crystallites or aggregates of intercalated nanocomposites clay-polymer are the sites of the beginning of acrylamide polymerization. The rate of water re-absorption was lower than in case of the primary water uptake up to period of time of 1000 min and was constant to 5000 min while the rate of primary absorption decreased substantially after 1000 min. The sorption capacity of nanocomposites for solutions simulating waste of nuclear power plants was 18 ml/g that was higher than absorption by natural bentonite (3.4 ml/g). Thus, the intercalated nanocomposites clay-polymer could be promising materials as components of the geochemical and water insulating barriers

Gymnastics' centre of gravity: the Fédération Internationale de Gymnastique, its governance and the Cold War, 1956–1976

International audienceFounded as the Bureau Des Fédérations Européennes De Gymnastique in 1881, the International Gymnastics Federation (FIG) was officially created in 1922. However, despite having over 100 national associations affiliated by the end of the twentieth century, it was dominated by Europeans until relatively recently. In particular, the former communist bloc of Eastern Europe had a particular hold on gymnastics from the 1950s onwards. This article uses the FIG as a case study to highlight the institutional, political and ideological rivalries within international sport. It reveals such influences on the sportification of gymnastics and, in doing so, offers new insights into the history of the Cold War, including the USSR’s ascension to the international sporting scene, and its power surrounding the ‘South Africa ban’ due to its Apartheid policy. Thus, this work allows us to understand how the FIG’s policies were, from an early stage, embedded in a twofold dynamic of East–West and North–South. Our study is based on official and administrative documents from national associations and the FIG, and on press review from several European countries