Hybrid organic-inorganic nanocomposites for ion-exchange processes

Two types of composite ion-exchangers, which are based on strongly acidic gellike cation-exchange resin and zirconium hydrophosphate, have been obtained. The first group contains both inorganic nanoparticles and their aggregates, the second one contains only aggregates. Analysis of differential porogrammes obtained with a method of standard contact porometry allowed us to estimate porous structure both of polymer matrix and inorganic constituent. Each stripe of the porogrammes has been related to structure element of polymer and ZrPh. Geometrical globular model has been applied to estimate a size of nanoparticles. A size of the nanoparticle size was shown to depend on their location: it reaches 16 nm, if the globules are placed in clusters of the polymer matrix, and 36 nm for aggregated nanoparticles in macropores. The results have been confirmed by data of scanning and transmission electron microscopy. Modification of ion-exchange resins causes transformation of porous structure of labile polymer matrix. The transformation occurs both at nano- and micro-levels. Recommendations regarding to structure of composite ion-exchangers for different applications are given. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2057

Study of the nonlinear instability of a longitudinal structure generated by a roughness element in the boundary layer of a straight wing

The results of experimental study of a nonlinear varicose instability of the streaky structure generated by roughness element in unswept-wing boundary layer are presented. Features of the varicose breakdown of longitudinal steady streaky structure such as modulation of structure in transverse and streamwise directions by secondary disturbance, occurrence of the new streaky structures and Lambda-structures downstream are shown. Spatio-temporal pictures of the hot-wire visualization of flow during spatial evolution of the streaky structures under influence of secondary high-frequency disturbance are discussed. Features of the adverse pressure gradient influence upon processes of the nonlinear varicose instability evolution and flow structure are revealed. Essential influence of the adverse pressure gradient on evolution of disturbances is shown. Comparison of varicose instability of the streaky structures generated in two different ways (the roughness element as in the given work, and continuous air blowing as in the earlier published work) is the carried out