Fine Chemical Technologies

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Vol 12, No 5 (2017)
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5-20 1307
Development of modern medical technologies would be impossible without the application of various materials with special properties. Over the last decade there has been a marked increase in interest in biodegradable materials for use in medicine and other areas of the national economy. In medicine, biodegradable polymers offer great potential for controlled drug delivery and wound management (e.g., adhesives, sutures and surgical meshes), for orthopedic devices (screws, pins and rods), nonwoven materials and scaffolds for tissue engineering. Among the family of biodegradable polyesters the most extensively investigated and the most widely used polymers are poly(α-hydroxyacid)s: polylactide (i.e. PLA), polyglycolide (i.e. PGA), poly-ε-caprolactone (PCL), polydioxanone and their copolymers. Controlling the molecular and supramolecular structure of biodegradable polymers allows tuning the physico-chemical and mechanical characteristics of the materials as well as their degradation kinetics. This enables selecting the optimal composition and structure of the material for the development of a broad range of biomedical products. Introduction of various functional fillers such as calcium phosphates allows creating bioactive composite materials with improved mechanical properties. To manufacture the highly dispersed biomedical materials for regenerative medicine electrospinning and freeze-drying are employed. Varying the technological parameters of the process enables to produce materials and devices with predetermined pore sizes and various mechanical properties. In order to increase the effectiveness of a great number of drugs the perspective approach is their inclusion into nanosized polymer micelles based on amphiphilic block copolymers of lactide and ethylene oxide. Different crystallization behavior of the lactide blocks and controlled regulation of their length allows producing micelles with various sizes and morphology. In this article we have attempted to provide an overview of works that are under way in the area of biodegradable polymers research and development in our group.
21-27 490
The aim of this work was to improve the physical, chemical and mechanical properties of epoxy composites with the use of nanosized aluminium oxide. The studies proved the possibility of directional control of the operational properties of epoxy composites by the use of small additions of nanosized aluminium oxide ensuring the creation of epoxy composites with high performance, satisfying the requirements of most industries. The rational content of aluminium oxide as a nanostructuring additive in an epoxy composition was selected (0,05 parts by weight). It ensures an increase in the complex of physico-mechanical properties (the breaking stress increases 3.3-fold, and the flexural modulus increases by 27%, the breaking stress in compression improves by 43%, the breaking stress and the tensile modulus of elasticity increases by 47-50%, the toughness increases 3-fold, and the hardness increases by 67%), while maintaining heat resistance. The introduction of nanosized aluminium oxide changes the parameters of the epoxy oligomer curing kinetics: the gelation duration increases from 45 to 75 minutes, and the duration of cure, from 53 to 100 minutes, while the maximum curing temperature is practically unchanged. Thus, the developed materials may be used for sealing electronic articles, for impregnating and filling components in aircraft engineering, shipbuilding and, automotive industry.
28-33 269
In this paper, we consider methods for producing artificial latexes based on butadiene-styrene thermoplastic elastomer in the presence of cationic surfactants, as well as their mixtures with nonionic and silicone surfactants. The obtained results are compared for the particle size distribution, and conclusions are drawn about the stability of the polymer suspension. The size of particles of polymer suspensions was determined by the method of photon correlation spectroscopy (dynamic light scattering) using a laser particle analyzer. This method allows us to consider the properties of the resulting polymer suspensions and directly draw conclusions about the effect of nature and the concentration of surface active substances on the stability of the resulting latexes. It can be assumed that in this case, structural- mechanical and electrostatic barriers form in the surface layers of the particles. The combined action of these barriers has made it possible to obtain stable polymer emulsions. Thus, it can be concluded that the used surfactant mixtures make it possible to increase the stability of artificial latexes in the stages of emulsification and distillation.


34-46 382
Extractive distillation of acetone-chloroform-n-butanol mixture with dimethylformamide in two-outlet column schemes is considered. Optimal parameters according to the total energy consumption criterion in the column boilers of the three extractive distillation schemes for this mixture separation are determined. Calculations were carried out in a design-verification version at 1000 kg/hr of the initial mixture with the concentrations of acetone, chloroform and n-butanol 71.3, 14.7 and 14.0% wt., respectively. Dimethylformamide concentration in the entrainer flow was set to 99.99 wt%. The main component concentration in the product stream was 99.9 wt% for chloroform and 99.5 wt%. for acetone and n-butanol. The parameters to be optimized were: the number of plates in the columns, the temperature and flow rate of dimethylformamide, reflux ratios, distillate flow rates and the position of the feed plates in the columns. The optimum location of the entrainer feed plate was found additionally in the extractive distillation column. Separation product concentrations served as the constraints of the optimization. The optimization was carried out in Aspen Plus with the use of a combination of Sensitivity Analysis and sequential quadratic programming (SQP). It is established that scheme P5 has the lowest energy consumption. In the first column of this scheme, n-butanol is separated, and then the azeotrope-forming components (acetone and chloroform) are separated by the extractive distillation subsystem. Energy consumptions for two other schemes (P1 and P2), in which dimethylformamide is used in the first column of the sequence, are significantly higher than for scheme P5 - by 69.1% and by 49.3%, respectively. The data obtained will be used: to synthesize and optimize the extractive distillation schemes including the subsystems with coupled thermal and material flows to separate the acetone-chloroform-n-butanol mixture; to estimate the energy efficiency of those schemes and to obtain the criterion for estimating the energy efficiency of systems with coupled thermal and material flows in the extractive distillation of multicomponent mixtures.


47-55 273
Results of testing a prototype light-emitting diod miniphotometer for rapid and sensitive elements determination both in laboratory and in field conditions are presented. The new photometer consists of two devices providing measurements of absorbance and diffuse reflectance, having a joint system of data management, registration and presentation of the results. The measurements of absorbance were registered in the visible spectrum. The explored reaction of Mn(II) with 1-(2-pyridylazo)-2-naphthol and the new reaction with 2-(2-quinolinazo)-5-diethylaminophenol were used to verify the device’s metrological parameters. Spectra obtained by means of the proposed photometer were compared to those for commercial photometers. A computer algorithm considering the difference in light-emitting intensity between diods was developed. The possibility of determination down to 1 mkg/ml metal ions in liquid samples was shown.
56-64 310
A method of the synthesis of plasmon gold nanoparticles by the reduction of HAuCl4 with organic reductants, such as formalin, sodium citrate and hydroquinone has been studied. It is shown that, depending on the concentration of the reagents, the temperature of synthesis and the type of the reducing agent, the position of the maximum of the plasmon band varies in a wide range from 520 nm to 720 nm. A one-stage method using hydroquinone as a reducing agent for the synthesis of long-wave plasmonic gold nanoparticles that form agglomerates of smaller particles with a plasmon absorption band in the red region of the spectrum is proposed. Since the resulting sol is rapidly precipitated due to the aggregation processes, it has been found necessary to use stabilizers for its subsequent application. The influence of some stabilizers (gelatin, as well as surface-active substances polydimethyldiallylammonium chloride and cetyltrimethylammonium bromid) on the stability of the gold sol synthesized by the hydroquinone method has been studied. It is shown that all the types of investigated stabilizers even in a minimal quantity provide the colloidal stability of the sol for several hours. However, only a natural polymer, gelatin, stabilizes the sol so that the maximum absorption of the plasmon band remains in the long-wavelength region of the spectrum.


65-70 324
The structure and properties of oil disperse systems (ODS) are mainly determined by the presence of paraffin hydrocarbons (n-alkanes) in the crude oil and natural gas liquid. Short-chain n-alkanes (С8-С17) are part of ODS dispersion medium. Under oil refining treatment, they concentrate in the distillate fractions and influence the operation characteristics of product liquid fuels and natural gas liquid.We studied the influence of hydrodynamic cavitation on the short-chain n-alkanes. Cavitation was produced by a high pressure disintegrator DA-1. A plunger pump produced compression pressure 50 MPa. Cavitation treatment was applied three times in a row. The research object was liquid oil paraffin containing 96.5% wt. n-alkanes С9-С21 (including 95% wt. С9-С17) and 2.5% wt. isoalkanes С10-С20; the balance was a mixture of other hydrocarbons. The results of GLC demonstrated that the total conversion of initial n-alkanes С14-С17 was not high, but it grew growing constantly: after the 1st cavitation cycle - 1.4%, after the 2nd cavitation cycle - 2.7%, after the 3rd one - 3.6%. At the highest conversion, the concentration of n-alkanes C8-C13 in liquid oil paraffin increased by 28% rel., and the concentration of n-alkanes C18-C22 - by 36% rel. The information obtained allows predicting the influence of the short-chain n-alkanes present in the oil feed on alterations of its hydrocarbon and fraction composition after cavitation.


71-78 246
The technique for the formalized description of functional models of chemical manufacturing is developed. The technique is based on graph theory. The model is described as a set of oriented labeled graphs that are hierarchically organized by the decompose relationship. First we describe the conversion of a single diagram to a labeled graph, including adding new nodes and edges. The nodes of the graph correspond to boxes, borders and branching points of the arrows at the diagram. The edges of the graph correspond to the arrows at the diagram. The graph descriptions of the model of base functional relationships such as output-input, output-control, output-mechanism are represented. We develop procedures to convert the border arrows and branch arrows. Conversion of branch arrows is performed depending on changes of the labels of branches. Branching of each arrow corresponds to a subgraph including several edges and perhaps additional nodes. Oriented labeled graphs are described by set-theoretic notation that contains the labels of the edges and the roles of nodes. The hierarchy of diagrams is specified by a decompose relationship, which includes the parent chart, the child chart and the decomposed box. As an example, we present the set-theoretic description of the functional model of vinyl acetate manufacturing. The application of mathematical apparatus built within the framework of graph theory for verification and analysis of functional diagrams based on the proposed formal description is an area for further research.
79-87 238
The analysis of experimental internal friction spectrum tgδ - f(T) shows that monocrystalline metallic materials possess the simplest spectrum. For those materials, dissipation of a part of the energy of external power impact exists in a form of internal friction background. The background increases slightly and monotonously at homologous temperatures θ < 0.2 ÷ 0.4, and it increases exponentially at θ ˃ 0.4. Taking into consideration the fact that monocrystalline systems may contain defects in the form of disturbance, and the concentration of point defects related to implantation atoms is minimal, one can suppose that this monocrystalline system consists of one aggregate subsystem having flat defects. Different analytical functions, which are often used in describing the inelasticity phenomenon, were studied as relaxation cores for describing the inelastic response of such subsystem in the area of increasing relaxation background of dissipative loss. It is shown that Rabotnov’s, Rzhanitsin’s and Havriliak-Negami’s cores don’t satisfy the asymptotic conditions for the convergence of series with positive values of incoming characteristics. In this case they cannot be used as relaxation functions describing the response of the aggregative subsystem in the temperature range which is higher than homologous temperature 0.4. Description of the viscoelastic response of the high-temperature background internal friction and, accordingly, of the temperature-frequency change of shear modulus is possible only when using Maxwell’s or Kolrausсh’s function which transforms into Maxwell’s function only at a single value of fractionality parameter.
88-96 230
A systemic analysis of the life cycle of products from elastomeric materials was carried out. The main modules of a management system for managing the life cycle - development, production and distribution of products from elastomeric composites on the basis of the integrated information system are described. The main control points of the process control are indicated. A detailed description of complex chemical-technological processes of multicomponent elastomeric composites structuring from the positions of a system approach based on a complex of information and production models is proposed. The model of an automated control system for the chemicaltechnological processes of elastomeric composites structuring based on vibration-rheometric data is considered, which is an example of the use of a control system based on indirect indicators. It is shown that the disturbing effects leading to the deviation of the process indices from the given ones are of a prescription and technological nature. The architecture of the integrated information management system for complex chemical-technological processes of multicomponent elastomeric composites mixing and structuring based on the production rules system is proposed. A block diagram of the algorithm for processing the main rheometric information of elastomeric composites structuring is given.

ISSN 2410-6593 (Print)
ISSN 2686-7575 (Online)