Vol 53, No 3 (2019)

The effect of finely dispersed iron powder on the relaxation behavior of highly elastic acrylate latex polymers was studied by dynamic mechanical relaxation spectroscopy. The introduction of a filler led to a decrease in the intensity of the maximum of dissipative losses of α relaxation and in the modulus defect of the polymer and to dissipative losses of β relaxation. Special attention was paid to relaxation effects at negative temperatures, which showed themselves as local dissipative processes of μ relaxation in the spectra of internal friction and on the temperature dependences of frequency.

A graphic analysis of the processing of phosphorites from Koksu (Karatau deposit) into extraction phosphoric acid (EPA) by the dihydrate–hemihydrate method was performed according to the equilibrium solubility diagram of the CaO–P₂O₅–SO₃–H₂O system. It was shown theoretically that EPA with 30.0% P₂O₅ can be obtained for practical purposes from common phosphate raw material of Koksu (24.5% P₂O₅). The main concentration and mass parameters that underlie the experiments on process development were evaluated.

Estimations on the characteristics of the partial oxidation conversion of gasification products of solid organic fuels to a tar-free synthesis gas via partial oxidation are based on a stationary thermodynamic model. Calculations of combustion temperature, composition of synthesis gas, and the energy characteristics for the conversion of the gasification products of wood to a synthesis gas in the use of oxygen and oxygen-enriched air are carried out. The influence of the amount of pyrolysis tar and their elemental composition on conversion characteristics is studied.

In this study, two extraction methods were used sequentially. In the first stage, colemanite process waste was subjected to scrubbing and decantation, and colemanite concentrate was obtained. In the second stage, leaching and filtration processes were carried out on the colemanite concentrate, and pure boric acid was obtained. Colemanite process waste (CPW) contains colemanite, calcite, quartz and others minerals. The boron oxide percentage of CPW was increased by the scrubbing method. Thus, impurities of the CPW were decreased. Scrubbed CPW is referred to as colemanite concentrate (CC). Boric acid extraction was investigated by the leaching of the colemanite concentrate in sulfuric acid solutions. The characterization of colemanite concentrate was determined by X-ray diffraction (XRD) analysis and X-ray fluorescence (XRF) analysis. The leaching parameters in this study were solid/liquid ratio, stirring speed, acid concentration, and reaction temperature. It was observed that the dissolution efficiency increased with increasing reaction temperature and with decreasing solid/liquid ratio and acid concentration. CPW is a problem for the environment; however, in this study, this CPW was converted into a valuable product (boric acid).

A systematic approach to the optimal organization of a binary distillation process based on information theory is presented. This approach allows to formulate conditions for optimal function distribution for a complex process, when the feed stream is separated into several product streams. The results of computational experiments based on this approach and known thermodynamic approaches that involve the minimization of exergy losses and entropy production are compared using a numerical example that models the separation process for a methanol–water mixture. The results of computational experiments based on the information-probabilistic approach to the optimal organization of a binary distillation process agree with results obtained by using thermodynamic approaches, evidencing the applicability of the information approach in the context of its integration into the general algorithm of chemical engineering system design based on the information approach.

A mathematical model of the vertical pneumatic transport of a polydisperse bulk material is proposed based on the theory of interpenetrating continua and supplemented by equations of interfractional interaction that account for particle collisions of different fractions. The fractional interaction forces determined by the collision of particles are comparable in value with the interphase interaction forces of particles with a gas. For particles of fine fractions, collisions with large particles exert a decelerating effect, while larger particles are “pushed” by smaller particles. This leads to a decrease in the spread between particle speeds.

This work is focused on the study of mechanical and physicochemical properties of an innovative and environmentally friendly composite material based on different sugar palm fiber (SPF) loadings (10–30 wt %) with thermoplastic polyurethane (TPU). A two-step technique was used (extrusion of TPU with SPF fibers at 190°C; rotational velocity of 40 rpm, followed by hot press 190°C for 10 min) to obtain the composites. The size of SPF was fixed at 250 µm, and different weight percentages (10, 20, and 30 wt %) of SPF were added in TPU to find the optimum composition. The mechanical (impact, tensile, and flexural) properties of the new (TPU/SPF) composite were studied as per ASTM standards. The Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and the X-ray Diffraction (XRD) were employed for structure and morphology study of TPU/SPF composites. The results proved that best tensile strength (14 MPa) and strain performance is shown with 10 wt %, while at 20 wt % exhibited maximum impact property. An increasing trend was recorded in flexural properties and tensile modulus with the increasing fiber loading. On the other hand, strain deteriorated with increment of fiber content.