Microplastics have been prepared by impregnating aramid and glass fibers with of polysulfone melts of various viscosities unfilled and filled with montmorillonite. A minimum of the melt viscosity has been found at a montmorillonite content of 1 wt %. Radial-transverse impregnation of multifilament fiber by a thermoplastic melt has been studied by the gravimetric method. Introduction into the polysulfone melt up to 1% of the filler at the initial stage of impregnation have almost no effect on the rate of the process; however, a decrease in it is observed as compared subsequently to impregnation with the melt containing no filler. It has been shown that torsional rigidity of microplastics, along with weight change, characterizes the degree of fiber impregnation.

The structure and rheological behavior of cellulose solutions in the high-polarity donor solvent N -methylmorpholine- N -oxide containing particles of layered aluminosilicates of various natures, namely, natural hydrophilic montmorillonite (Cloisite Na + ) and hydrophobized montmorillonite (Cloisite 20A), are studied. The rheological properties of the mixed systems cellulose- N -methylmorpholine- N -oxide-Cloisite Na + and cellulose- N -methylmorpholine- N -oxide-Cloisite 20A are similar, although their structures are different. This similarity may be explained by the fact that the highly developed structure of the cellulose matrix phase resulting from strong interactions between polar components of the system exerts the decisive effect on the character of flow of mixed solutions. Therefore, the filler assumes the minor role. The concentration dependences of solution viscosity turn out to be atypical when the content of moisture in Cloisite 20A is increased above the equilibrium value and when M 2 Cloisite Na + nanoparticles modified in a certain manner are introduced into cellulose solutions.

Исследована структура и реологические свойства растворов целлюлозы в высокополярном растворителе донорного типа N-метилморфолин-N-оксиде, содержащих частицы слоистых алюмосиликатов различной природы: природного гидрофильного (Cloisite Na+) и гидрофобизованного монтмориллонита (Cloisite 20А). Реологическое поведение исследованных смесевых систем целлюлоза–N-метилморфолин-N-оксид–Cloisite Na+ и целлюлоза–N-метилморфолин-N-оксид–Cloisite20А, несмотря на различия их структуры, близко друг другу. Причиной такого подобия можно считать определяющее влияние на характер течения смесевых растворов высокоразвитой структуры целлюлозной матричной фазы, формирующейся в результате сильных взаимодействий между полярными компонентами системы. Поэтому роль наполнителя становится второстепенной. Концентрационные зависимости вязкости растворов оказываются нетипичными при увеличении содержания влаги в Cloisite 20А выше равновесного содержания и при введении в целлюлозные растворы модифицированных определенным способом наночастиц М2Cloisite Na+.

A study was made of the effect of montmorillonite on the curing of an epoxy oligomer with diaminophenylsulphone. It was shown that the introduction of the clay in all cases leads to an increase in the viscosity of the epoxy oligomer. It turned out that ultrasound has a considerable effect on the viscosity of a composite containing modified clay.

An examination is made of the effect of modifying montmorillonite with organic compounds and its ultrasound treatment on the rheological properties of filled epoxy oligomers and the structure and physicomechanical properties of cured composites. To improve the physicomechanical properties of filled epoxy composites, it is recommended that use be made of modified montmorillonite of grade Cloisite 30B, which has the best compatibility with the epoxy matrix.

Phase state and morphological features of solutions of cellulose blends with rigid-chain thermotropic LC copolyesters and isotropic poly( m -phenyleneisophthalamide) in the highly polar donor solvent N -methylmorpholine- N -oxide are studied by DSC and polarization microscopy. The ternary phase diagram for the cellulose-copolyesters- N -methylmorpholine- N -oxide system is constructed. Rheological characteristics of the prepared solutions are studied using capillary and rotary rheometers under the regimes of continuous and periodic shear deformation. Rheological characteristics of cellulose solutions with copolyesters in N -methylmorpholine- N -oxide with their different phase states are shown to change in accordance with the traditional mechanism of flow for solutions with high specific interactions between their components. However, the character of the rheological behavior of mixtures of cellulose with poly( m -phenyleneisophthalamide) in N -methylmorpholine- N -oxide primarily stems from structural-morphological transformations in solutions taking place upon deformation.

The rheological properties of HDPE specimens treated with oxygen or hydrogen peroxide in a melt were studied. Measurements showed that the oxidation leads to an increase in shear viscosity and elongational viscosity and the appearance of a hysteresis in the flow curves (thixotropy) in the low-shear-rate region, as well as to an increase in the eloncation at break and the melt strength. These effects were observed only at high temperatures (T > 170degreesC). IR spectroscopy and gel-permeation chromatography data suggest that this treatment of PE melts results in the formation on chains of reaction sites leading to the generation of rare long-chain branches. The presence of branched structures enhances the resistance of the melt to tensile strain and facilitates improvement of the processability and quality of articles manufactured by blow molding.

Using the methods of steady-state and small-amplitude oscillatory shear, the rheological properties are studied for liquid mixtures of a paraffin oil (the model matrix) and a polypropylene melt with a clay modified with various agents. Such systems are precursors of nanocomposites. The modification of microparticle surfaces involves their treatment with either dioctadecyldimethylammonium chloride, various block copolymers, or a mixture of these substances. The typical rheological behavior of polypropylene-clay systems under shear flow consists in an increasing viscosity (and dynamic moduli) at low shear rates (frequencies), accompanied by the appearance of the yield point. At high shear rates, the viscosity decreases as the degree of filling increases. Exceptions are systems that contain clay with the immobilized ethylene oxide-ethylene block copolymer: the viscosity of these systems decreases as the degree of filling increases within the entire studied range of shear rates. The proposed explanation of the experimental facts is based on the assumption that apolar blocks of modifying copolymers immobilized on the surface of particles, being partially compatible with polypropylene macromolecules, lead to structure formation of the system and make its behavior viscoplastic. The strength of bonding of the block copolymers with the surface of nanoparticles and polypropylene is determined by the nature Of the block copolymer and depends on the intensity of deformation.

Rheological properties of polymers with narrow and wide molecular weight distributions filled by carbon black with high structurizing property have been studied in a wide range of shear stresses and shear rates in steady shear. The strength of the structures formed by the particles of the dispersed phase was characterized by the yield stress. It was shown that the yield value depends on the molecular parameters of the dispersion medium. For polydisperse polymers it is associated with the adsorption of low molecular weight fractions on the surface of the filler particles and therefore depends slightly on the molecular weight (MW) of the matrix. For monodisperse polymers the strength of the structure increases with increasing MW. In this case the strength reaches larger values than for polydisperse polymers.

Fibril formation in mixtures of incompatible polymers, in this case polyethylene and polystyrene, has been studied with their melt being deformed in a uniform shear field. It has been found that when polyethylene is present in a smaller amount, it may form very long fibrils 5 to 8 µm in diameter in the deformed mixture. The formation of such fibrils is determined by the relationship between the viscosity ratio of the mixture components and shear stress. Also, just as in the case of a nonuniform shear field in a flow through a duct, fibril formation in melts of mixtures of incompatible polymers in a uniform shear field takes place upon reaching a certain shear stress. The lower the ratio between the viscosities of the fibril-forming polymer and the other component, the lower this shear stress.

As was shown in some works, the morphology of mixtures of incompatible polymers depends on a number of factors, such as composition of the mixture, viscoelastic properties of the components, conditions of their mixing, and surface tension at the interphase. The rheological properties of the components and, consequently, the conditions of their mixing produce a tangible effect on the phase state of the mixture and its microstructure. The morphology, in turn, determines to a great extent the mechanical properties of the products based on mixtures of incompatible polymers. For example, the anisometry of the dispersed phase particles leads to anisotropy of the mechanical properties. In some cases, for instance, when a mixture of polymers is pressed through ducts, the dispersed phase is observed to form a fibrous structure, which results in one polymer being reinforced by the other.

Mixtures of linear polyethylene with polystyrene were used in studying the fiber formation pattern of mixtures of incompatible polymers whose melts were forced through dies. Variables included the viscosity of the components, mixture preparation conditions, and shear stress. It has been established that the process of fiber formation occurs within a definite range of shear stresses, dependent on the viscosity ratio of the fiber-forming polymer and the polymer serving as the dispersion medium. When this ratio is equal to or less than unity, mixtures containing the fiber-forming component in the form of a finely dispersed phase yields continuous fibers several micrometers in diameter within a broad range of shear stresses. At greater values of the component viscosity ratio (tens of units), no fiber formation takes place in the mixtures.

The viscous properties of SBS block copolymers (of “Cariflex TR-1102” in this work) have been determined with the rate of shear being varied by 108 times. It has been shown that in the region of low shear rates the polymer behaves as a structured highly concentrated disperse system which exhibits sharply pronounced thixotropy. In the region of high shear rates, the viscous properties of the polybutadiene matrix are of decisive importance. At low values of shear stress the compliance of the SBS block copolymer exceeds that of the polybutadiene matrix almost by a decimal order.

Rheological properties of carbon black filled polyisobutylene samples (of low and high molecular weight) have shed light on the relationship between the behaviour of disperse and polymeric systems. At sufficiently high filler concentration a structural skeleton seems to appear. This affects the properties.