IR Fourier Spectroscopy Research Articles

Development of solid dispersion system from milk thistle dry extract by solvent method

Introduction. Silymarin is one of the main components used in preparations for hepatotropic therapy. Silymarin is contained in the dry extract of seeds and fruits of milk thistle (Silybum marianum L. Gaertn.), however it has poor bioavailability due to the crystalline state and low solubility of silymarin flavolignans in water at room temperature, as well as their poor absorption. One of the methods for increasing the bioavailability of medicinal substances consists in their introducing into solid dispersion systems (SDS). The most suitable method for obtaining SDS with extracts is the solvent method, since it does not require the use of a high temperature regime during the obtaining process of SDS.Aim. To develop the technology for solid dispersion system from milk thistle dry extract by solvent method to increase the bioavailability of this phytosubstance.Material and methods. The obtaining of the solid dispersion systems from milk thistle dry extract by solvent method was carried out with polyvinylpyrrolidone (PVP K-29/32), polyvinylpyrrolidone vinyl acetate 6 : 4 (PVPVA 64), hydroxypropylmethylcellulose (HPMC), gelatin and sodium lauryl sulfate (SLS). The quality indicators of the SDS: particle size distribution, bulk density, residual humidity and hygroscopicity were carried out according to the methods of the State Pharmacopoeia of the Russian Federation (GP RF) XV edition. The quantitative determination of biologically active substances (BAS) was carried out in accordance with the GP RF XV ed. by the amount of flavolignans in terms of silybin.Results and discussion. During the development of solid dispersion systems by solvent method, SDS samples from milk thistle dry extract (MTDE) with different polymers were studied. As a result of studying the particle size distribution, several SDS samples were selected. The SDS samples were compared with the MTDE sample. The "Dissolution" test showed that the micronization of MTDE in form of SDS by solvent method, containing polyvinylpyrrolidone vinyl acetate – PVP VA 64 is the best alternative for increasing the silybin releasing-degree from the extract and increasing its bioavailability. According to the content of the sum of flavolignans in terms of silybin, the selected SDS sample meets the requirements of the normative documentation for milk thistle dry extract. In addition, the conditions for the development of SDS do not significantly affect the quantitative content of silybin compared with the content of the control sample of MTDE. The technological characteristics of SDS have been investigated and their qualitative improvement compared to the MTDE sample has been established. The interaction between the polymer carrier and the milk thistle extract was evaluated by the IR-fourier spectroscopy method.Conclusion. The SDS from milk thistle dry extract was developed by solvent method. For the developed SDS, quality indicators such as the content of the sum of flavolignans in terms of silybin, residual humidity, bulk density, particle size distribution and hygroscopicity were determined. The solid dispersion system from milk thistle extract was analyzed by IR-fourier spectroscopy. The physico-chemical compatibility between the milk thistle extract and the polymer-carrier polyvinylpyrrolidone vinyl acetate is shown. The development of the SDS from milk thistle dry extract significantly increased the bioavailability of the phytosubstance by increasing the silybin releasing-degree of the SDS by 3 times compared with the control sample of MTDE.

Composite material from polylactic acid and modified fire flax: synthesis and properties

Abstract The paper presents data on the synthesis of a composite material based on polylactic acid and fire flax powder. To improve adhesion between the polymer matrix and the plant filler, the fire flax powder was modified (acylated) with acetic anhydride. The IR Fourier spectroscopy method established the acylation reaction of fire flax powder. After modification with acetic anhydride, an increase in the intensity of the following peaks is observed in the IR Fourier spectrum: at 1747 cm-1, at 1374 cm-1 and at 1234 cm-1. Composites based on polylactic acid were manufactured, which contained the modified filler in concentrations of 30%, 40% and 50% by weight. Physicomechanical, electron microscopic and thermal studies of the developed polymer composites are presented. The tensile strength of the studied composites was determined using standard methods according to ISO 527-2:2012. The composite containing 50 wt. % modified fire flax powder has the following characteristics: tensile strength – 6.53 MPa, relative elongation - 13.89%, density - 1.247 g/cm3, maximum permissible operating temperature (sample weight loss up to 5 wt. %) - 254 ° C. This study promotes the development of biodegradable materials by offering polylactide-based composites with the addition of fire flax as an alternative to non-degradable synthetic fillers. The use of agricultural waste not only reduces the cost of production, but also solves the problem of biomass utilization, which opens up prospects for the creation of environmentally friendly composites in various industries. The research methodology also makes it possible to modify natural components, expanding their use and potentially replacing traditional plastics.

Changes in the Structure and Properties of Silicon During Ytterbium Doping: The Results of o Comprehensive Analysis

In this work, a comprehensive study of the structural, chemical and electrophysical properties of monocrystalline silicon (Si) doped with ytterbium (Yb) has been carried out. The alloying was carried out by thermal diffusion at a temperature of 1473 K in high vacuum conditions followed by rapid cooling. Atomic force microscopy (AFM), infrared Fourier spectroscopy (FTIR), deep level spectroscopy (DLTS) and Raman spectroscopy (RAMAN) were used to analyze the samples obtained. AFM images of the surface of the doped samples demonstrated significant changes in topography. The RMS surface roughness increased from less than 10 nm to 60-80 nm, and the maximum height of the irregularities reached 325 nm. These changes are explained by the formation of nanostructures caused by the uneven distribution of ytterbium atoms in the silicon crystal lattice, as well as the occurrence of internal stresses. "IR-Fourier spectroscopy showed a significant decrease in the concentration of optically active oxygen (NOopt ) by 30-40% after doping. This effect is associated with the interaction of ytterbium atoms with silicon and a change in the chemical composition of the material. The RAMAN spectra revealed the formation of new phases and nanocrystallites in the doped samples. Peak shifts and changes in their intensity were detected, indicating a rearrangement of the crystal lattice caused by the introduction of ytterbium. It was calculated that the diffusion coefficient of ytterbium in silicon is 1.9×10-15 cm2/s, which indicates a slow diffusion process characteristic of rare earth metals. Electrical measurements carried out on the MDS-structures showed a shift in the volt-farad characteristics towards positive bias voltages, which is associated with a decrease in the density of surface states at the Si-SiO₂ interface and the appearance of deep levels with an ionization energy of Ec-0.32 eV.

Formation of Hybrid Membranes for Water Desalination by the Method of Membrane Distillation

A method has been developed for the formation of hybrid membranes consisting of a hydrophilic microporous substrate and a hydrophobic nanofiber polymer layer deposited by electroforming. A track-etched membrane made of polyethylene terephthalate was used as a hydrophilic microporous substrate, on the surface of which a thin layer of titanium was applied by magnetron sputtering to ensure adhesion of the nanofiber layer. Simultaneously, the titanium coating was used to make a conductive track-etched membrane that served as a collector electrode. It is been shown that the application of this method for the formation of polymer coatings when used as a starting material for the formation of polyvinylidene fluoride nanofibers makes it possible to obtain a layer with highly hydrophobic properties, the water contact angle of the surface of which, depending on the deposition density, averages 143.3 ± 1.3°. A study of the morphology of the nanofiber coating shows that it has a microstructure typical of non-woven materials. The nanofibers forming the porous system of this layer have a wide range in size. The study of the molecular structure of the nanofiber layer by IR-Fourier spectroscopy and X-ray diffraction analysis showed that its structure is dominated by the β-phase, which is characterized by a maximum dipole moment. It is been shown that the hybrid membranes of the developed sample provide high separation selectivity when desalting an aqueous solution of sodium chloride with a concentration of 26.5 g/l by membrane distillation. The salt rejection coefficient for membranes with a nanofiber layer density from 20.7 ± 0.2 to 27.6 ± 0.2 g/m2 in the studied mode of the membrane distillation process is 99.97−99.98%. It has been established that the use of a highly hydrophobic nanofiber layer with a developed pore structure in combination with a hydrophilic microporous base makes it possible to increase the productivity of the membrane distillation process. The value of the maximum condensate flow through the membranes is on average 7.0 kg m2/h and its depends on the density of the deposited nanofiber layer.

Chankanai Zeolite Modified with Heteroatomic Derivatives of 3-Aminopropyltriethoxysilane as an Effective Sorbent for Ag(I), Co(II)

Bis-N,N-(3-triethoxysilylpropyl)thiosemicarbazide 3 was obtained by the condensation of 3-aminopropyltriethoxysilane 1 with thiosemicarbazide 2. Ethyl ether N-[3-(triethoxysilyl)propyl]-b-alanine 5 was obtained by the interaction of an equimolar amount of aminopropyltriethoxysilane 1 and ethyl acrylate 4 (aza-Michael reaction). Synthesized functional organosilanes 3 and 5 were successfully immobilized on the surface of natural zeolite Z (Chankanai deposit, Kazakhstan). Compounds and materials have been studied by NMR and IR Fourier spectroscopy and X-ray diffraction analysis. The elemental composition and morphology of modified zeolites Z3 and Z5 were studied using SEM-EDX analysis. The modification of zeolite by organosilanes 3 and 5 leads to changes in the surface structure of the material: with the enlargement of particles and agglomerates, the surface becomes more homogeneous and less porous. This indicates a high degree of zeolite coverage by the modifier layer. The study of the sorption characteristics of the initial Z and modified zeolites (Z3 and Z5) showed a high sorption capacity relative to Ag(I) and Co(II) (static sorption capacity, SSC = 35.85–23.92 mg/g), whereas the SSC values for Z were SSC = 20.63 and 16.64 mg/g. The adsorption of Ag(I) and Co(II) ions was studied in solutions prepared using Co(NO3)2·6H2O, AgNO3 and distilled water. The choice of the initial concentration of metal ions, as well as the pH of the solutions, corresponded to the composition of wastewater from real electroplating production. Zeolites Z3 and Z5 can be used in various sectors of industry, in ecology and for medical purposes as inexpensive and effective adsorbents (enterosorbents) of heavy and noble metals.

First comb-like copolymer of poly(ethyl 2-cyanoacrylate) grafted as a side-chain to dextran

The first comb-like cyanoacrylic copolymer was synthesized by anionic polymerization of ethyl 2-cyanoacrylate in an aqueous solution of dextran of Mw = 50 ± 5 kDa. The copolymer was explored by NMR and Fourier IR spectroscopy, as well as by MALDI-TOF mass-spectrometry methods. It contains up to 10 cyanoacrylate units grafted to anhydroglucose cycles of dextran main chain, multi- substituted glycose units were not detected.

Fibre-reinforced geopolymer (FRG) cemented aeolian sand flexural properties and microproduct evolutionary processes

To reveal the flexural behaviour and microproduct evolution mechanism of FRG cemented aeolian sand, four factors, namely, sodium hydroxide dosage, water-solid ratio, fibre dosage, and fibre length, were classified into mutually independent levels and combined to form a set of test matrices for the design of orthogonal tests. Using DIC digital scattering technology to analyze the evolutionary process of specimen ring-breaking and employing scanning electron microscopy to explore the polymerization product micro-morphology, evolutionary process, pore defects, and analyze the fiber endowment morphology and the destruction mode; the use of EDS spectroscopy, X-ray diffraction, Fourier IR spectroscopy, and other technical means to analyze the polymerization product chemical composition, elemental distribution, and evolutionary characteristics. The results of the study show that the 28-day flexural performance of FRG cemented wind-blown sand as a filling material is significantly affected by various factors in the following order of magnitude: sodium hydroxide dosage > water-solid ratio > fibre dosage > fibre length. The optimal combination from the local test is: sodium hydroxide dosage of 1.4 %, the water-solid ratio of 0.32, the fibre dosage of 0.5 %, and the fibre length of 12 mm. With the increase in load, the value of the displacement field increases continuously, indicating a greater degree of specimen damage. As the reaction proceeds, the polymerization product's morphology evolves from rod-like to flaky, ultimately stabilizing into a network structure. The main elements in the product include C, O, Si, Al, and Ca, indicating that the polymerization product is a C-(A)-S-H gel. A reasonable distribution of discrete ductile fibers can play a positive role inside the specimen, acting as a bridge. The damage behavior under bridging can be divided into fiber debonding, producing slippage behavior, and fiber damage, leading to fracture behavior. The results of the study provide a scientific basis for the design, preparation, and application of solid waste filling materials, thereby promoting the development of materials science and engineering.

Pyrolytic Decomposition of Polyethylene in the Presence of Aluminosilicate Materials Containing Nickel Oxide

The work is devoted to the study of the pyrolysis of high-density polyethylene (PE) in the presence of aluminosilicate materials containing nickel oxide. The process of catalytic pyrolysis of plastics makes it possible to convert polymers into chemical compounds, which can later be used as an additional source of fuels, raw materials for the chemical industry or polymer production. The physicochemical parameters of materials containing nickel oxide have been established using the following methods: IR-Fourier spectroscopy; x-ray diffraction analysis; N2 physical adsorption method; thermogravimetric analysis; pyrolytic gas chromatography. The dependences of the chemical composition of PE pyrolysis products on the type of support used and the presence of nickel oxide. The presence of nickel oxide in the studied aluminosilicates increases the Lewis acidity, which increases the content of aromatic compounds in the pyrolysis products. The activation energy of the PE pyrolysis process in the presence of MCM-41 containing nickel oxide was calculated from experimental data.

Nature of serpentinite interactions with low-concentration sulfuric acid solutions

Abstract The nature of serpentinite interaction with low-concentration sulfuric acid solutions is studied. Using IR-Fourier spectroscopy, X-ray, and serpentinite leaching with sulfuric acid solutions containing 10–60% of stoichiometrically required amount (SRA) of H2SO4 (taken relative to the molar magnesium content in serpentinite), it is shown that the appearance and influence of silica on the course of serpentinite dissolution is detected at concentrations of 30–40% of SRA of H2SO4. On the basis of the obtained results, this article points out the technological, economic, and ecological advantages of use of sulfuric acid solutions of low concentrations in the process of acid processing with the aim of producing magnesium salts.

Dynamics of rheological and biochemical blood parameters of patients with an intermediate stage of the dry form of age-related macular degeneration before and after serum cascade filtration

BACKGROUND: One of the socially significant ophthalmic diseases is the dry form of the age-related macular degeneration, the key feature of which consists in a slowly progressing damage to the pigment epithelium and the formation of drusen. However, the basic mechanisms of pathogenesis are still not completely clear nowadays. AIM: The aim is, using the data of OCT, OCT-angiography and visometry, to study the dynamics of structural and functional parameters of the macular area, as well as the dynamics of rheological and biochemical blood parameters in patients with an intermediate stage of the dry form of age-related macular degeneration before and after the use of serum cascade filtration. MATERIALS AND METHODS: The study included 63 patients (94 eyes) with an intermediate stage of the dry form of age-related macular degeneration. Patients were randomly separated into two groups. The first (main) group consisted of 34 patients (52 eyes), in whom serum cascade filtration was performed; the second group (control) group included 29 patients (42 eyes) who did not receive any specific treatment. In patients of the main group, before and after the serum cascade filtration course (1 month after the start of follow-up), in 6 and 12 months, in addition to standard ophthalmological examination, as an indicator of the efficacy of performed serum cascade filtration, the ultrasound triplex scanning in color Doppler mapping mode with an assessment of blood flow velocity in the posterior short ciliary arteries, Fourier IR spectroscopy, and the testing of the serum and blood viscosity were performed. Patients in the control group also underwent a similar examination at 1, 6, 12 months after the start of follow-up. RESULTS: According to optical coherence tomography, optical coherence tomography-angiography and visometry data, we found a positive dynamics of structural and functional parameters of the macular retina and an improvement in blood rheological parameters with an increase in microcirculation indices against the background of the serum cascade filtration use in treatment of patients with an intermediate stage of the dry form of age-related macular degeneration. At the same time, a statistically significant difference between the two groups begins at 1 month and persists for 12 months of follow-up, being an evidence of the stabilization of the pathological process. CONCLUSIONS: This study showed that after the serum cascade filtration in patients with an intermediate stage of the dry form of age-related macular degeneration, against the background of an improvement in blood rheological and biochemical parameters, there was an improvement in structural and functional parameters of the macular area, which consisted in a decrease of the volume of the drusenoid retinal pigment epithelium detachment and in a visual acuity amelioration.

Synthesis, Characterization and Application of New Polymers Imprinted with Zinc (II) Ions

In this work, molecularly imprinted polymers with zinc imprints and their comparison polymers without imprints were synthesized. A comparative characterization of the physical parameters of the synthesized zinc-imprinted (ZnIP) and non-imprinted (NIP) polymers was carried out using the methods of elemental analysis, conductometry, scanning electron microscopy, and IR-Fourier spectroscopy. The ability of the resulting polymers to molecularly recognize zinc was evaluated. Based on experimental data on static adsorption, the adsorption capacity of ZnIP and NIP was determined using an atomic emission spectrometer. It was found that ZnIP is characterized by better physical parameters and a higher ability for molecular recognition of zinc compared to NIP. ZnIP with zinc imprints were found to have better sorption capacity for zinc than their reference polymers. The sorption of zinc by molecular imprinted ZnIP is mainly due to the complex formation and pores of the initial carbon product. The synthesized ZnIP have increased porosity. The presence of pores with a diameter <50 nm in ZnIP is associated with voids formed after acid hydrolysis, which is clearly visible in images recorded by scanning electron microscopy. Thus, the possibility of using ZnIP as a selective sorbent has been established.

Aging of Adhesives of External Reinforcement Systems of Building Structures. Part 2. Structural Studies

The structural changes of cross-linked epoxy polymer adhesive for external reinforcement systems of building structures after exposure to artificial climatic factors have been studied by the method of IR Fourier spectroscopy. The aim of the study was to determine the significance of influencing factors (UV radiation, temperature, water and alkaline environment) for the development of a method for accelerated assessment of the durability of selected systems. The objectives of the study were to identify the mechanism of aging and obtain differential spectra of aged and initial samples. The processes of destruction of samples of cross-linked epoxy polymer of amine curing under the influence of artificial climatic factors of aging have been studied by IR spectroscopy. It has been established that the most significant factors influencing structural changes in the polymer are UV radiation and an alkaline solution of NaOH and KOH.

Метод Фурье ИК-спектроскопии в исследовании эякулята в норме и с олигозооспермией

The optical properties of the components (plasma, spermatozoa, protein and a solution after protein isolation from plasma) of a series of 24 ejaculate samples according to spermatograms in normal and with oligozoospermia were studied by Fourier IR spectroscopy. The analysis of the complex of spectral data obtained for a series of samples of the "norm" category showed in 50% of cases the presence of pronounced pathology in the optical properties of ejaculate, plasma and sperm. For the remaining 50% of the samples, the presence of spermatozoa of satisfactory quality in terms of material composition (proteins, lipids, carbohydrates) was noted with already well-marked signs of pathology in the ejaculate and plasma. A comparative analysis of their optical properties made it possible to note that the absence of clearly defined Amide-I and Amide-II bands in the spectra and the presence of peptide bands in the 1593–1572 cm-1 region is a stable sign of an existing or incipient pathology. Samples of the oligozoospermia category are quite well identified by the spectra of the cellular part of the ejaculate. The results of the study may be useful in modernizing clinical techniques and diagnostic approaches to the problem of male fertility.

SOFT MECHANOCHEMICAL SYNTHESIS OF CuO/ZnO/AL2O3 CATALYST FOR METHANOL PRODUCTION

In the work, using a set of methods for physicochemical studies, such as X-ray phase, X-ray diffraction, synchronous thermal and energy-dispersion analysis, scanning electron microscopy, low-temperature adsorption-desorption of nitrogen, IR-Fourier spectroscopy, the processes occurring at the stage of mechanochemical activation and further heat treatment of the Cu(NO3)3·3H2O/Zn(NO3)3·2H2O/Al(NO3)3·9H2O/H2C2O4·2H2O were studied. It has been established that at the stage of mechanochemical activation, intensive interaction of copper and zinc nitrates with oxalic acid occurs with the formation of one-water copper oxalate (CuC2O4∙Н2О) and two-water zinc oxalate (ZnC2O4∙2Н2О). The formation of oxalates occurs at the initial moment of activation 0-15 min, which is confirmed by the data of IR spectroscopy, X-ray phase and thermal analysis. The calcination of the samples leads to the formation of the ternary oxide system CuO/ZnO/Al2O3 and the interaction of copper and zinc oxides with the formation of a solid solution. It is shown that with an increase in the MCA time, the size of the coherent scattering regions decreases from 152 Å for the initial sample to 115 Å after 60 min of treatment. In this case, the accumulation of defects in the crystal structure occurs from 0.24 to 0.72%, respectively. The value of the specific surface passes through a maximum and at 30 min of treatment is 67.1 ± 0.3 m2/g. During processing, a mesoporous structure of the catalyst is formed with a total pore volume of 0.132 cm3/g. For the scaling process or the selection of other types of mills, the values of the supplied energy were calculated. It has been established that in order to obtain a catalyst with properties close to industrial analogs of leading foreign manufacturers, it is necessary to carry out treatment with an input energy of 79 kJ/g, and the calcination process should be carried out at a temperature of 350 °C and a duration of 360 min.

NOVEL THERMOPLASTIC ELASTOMERS BASED ON PVDF/SKF-32: EFFECT OF COMPOSITION ON TECHNOLOGICAL AND PERFORMANCE CHARACTERISTICS

Thermoplastic elastomers (TPE) based on SKF-32 fluorine rubber and polyvinylidene fluoride, PVDF (polyvinylidene fluoride content ranges from 30 to 70% relative to rubber) were investigated. The mixes have been produced by using a Brabender-type rotary micromixer. Such thermoplastic elastomers can be an alternative to traditional oil & fuel resistant butadiene-nitrile-based rubbers and can be used in manufacture of sleeves, hoses and tubes for pumping aggressive liquids and gases, wires/cables insulation, fuel storage tanks, valves, etc. Traditional methods of plastics processing can be used to manufacture this materials. It was established that the crystallinity degree increases with the rise of PVDF content. That fact is confirmed by the IR-Fourier spectroscopy data and differential scanning calorimetry. It was shown that the hardness and strength of TPEs increases with the rise of PVDF content. The tensile stress for TPEs containing 50% or more of PVDF are higher than those for conventional oil & fuel resistant rubber IRP 1078. The obtained TPEs possess high resistance against AI-92 grade gasoline, 80% sulfuric acid, 50% sodium hydroxide, and I-40 oil. They also retain their physical and mechanical properties even after three cycles of reprocessing. The TPE with the 1:1 thermoplastic : elastomer ratio, has been vulcanized using a peroxide vulcanizing system at varying concentrations. The dynamic vulcanization is confirmed by a decrease in the swelling degree of the obtained materials in solvents with an increase in the content of the vulcanizing agent. Peroxide dynamic vulcanization has not lead to a significant increase in physical and mechanical parameters, however, it resulted in an increase in chemical resistance of against aggressive solvents.

STUDY OF THE EFFECTIVENESS OF THE INFLUENCE OF PLASTICIZERS AND FUNCTIONAL ADDITIVES IN THE RECEIVING OF THERMOPLASTIC STARCH ON ITS FILM-FORMING AND DESTRUCTIVE PROPERTIES

A literature review on the production of thermoplastic starch (TPS) with various plasticizing additives as a component of biodegradable polymer compositions was conducted. Plasticizing additives with different functional groups, due to which starch modification occurs, were analyzed. In order to expand the spectrum of functional additives for the formation of TPS, the introduction of acids with different amounts of carboxyl groups: citric, oxalic, oleic, stearic was studied. The technological parameters of thermomechanical processing of starch compositions and the quantitative composition of the components are determined. Physical and mechanical tests of strength and elasticity of film samples of TPS compositions and compatible with synthetic polymer were carried out. In order to obtain the structural characteristics of TPS and TPS films with polyethylene, studies were carried out by IR-Fourier spectroscopy and mass spectrometry. Studies of the effect of UV irradiation on the degradability of TPS compositions after exposure in a climate chamber for 90 days were conducted. It was found that the loss of strength and elasticity of TPS and TPS+PE film samples is (82–90)%, elasticity (60–70)%, depending on plasticizing and structure-forming additives and their amounts.

The Effect of High Nitric Oxide Concentrations on Oxygenators in Cardiopulmonary Bypass Machines (Experimental Study)

The aim of the study. To study the effect of high nitric oxide concentrations on hollow polypropylene fibers of oxygenators.Materials and methods. The study was conducted in two stages. At the first stage, we evaluated the stability of oxygenator membrane made of hollow polypropylene fibers after six hours of exposure to air-oxygen mixture containing NO at 500 parts per million, or 500 pro pro mille (ppm) concentration, using mass spectrometry and infrared spectroscopy. At the second stage, an experiment with cardiopulmonary bypass (CPB) was conducted on 10 pigs. In the study group (n=5) animals sweep gas was supplied to the oxygenator as an air-oxygen mixture with NO at 100 ppm. In the control group animals (n=5) an air-oxygen mixture was used without NO. The CPB lasted for 4 hours, followed by observation for 12 hours. NO, NO2 (at the inlet and outlet of the oxygenator), and the dynamics of methemoglobin were evaluated. After weaning of animals from CPB, the oxygenators were tested for leakproofness, and scanning electron microscopy (SEM) was performed.Results. The oxygenator made of polypropylene hollow fibers retained its gas transfer parameters after six hours of exposure to air-oxygen mixture containing NO at 500 ppm. Based on IR-Fourier spectroscopy findings, NO did not affect structural integrity of polypropylene membranes. NO added to gas mixture at 100 ppm did not increase NO2 to toxic level of 2 ppm in 91% of control tests during 4 hours CPB in pigs; mean value was 1.58 ± 0.28 ppm. Methemoglobin concentration did not exceed the upper limit of permissible level (3%), and there were no statistically significant differences with the control group. All tested oxygenators have passed the leakproofness test. According to SEM findings, larger amounts of fibrin deposits were found in the control group oxygenators vs study group.Conclusion. There were no negative effects of NO at 500 ppm concentration on the oxygenator membrane made of hollow polypropylene fibers. NO at 100 ppm in a gas-mixture supplied to oxygenators did not lead to an exceedance of safe NO2 and methemoglobin concentrations in an animal model. Reduced fibrin deposits on hollow fibers of polypropylene oxygenator membranes were observed when with NO at a level of 100 ppm was added to a gas mixture.

Preparation of High-Transparency Phosphenanthrene-Based Flame Retardants and Studies of Their Flame-Retardant Properties.

Transparency is an important property for polymer flame retardants, especially epoxy resin (EP) flame retardants, and flame-retardant epoxy resins that maintain a high transparency and low chromatic aberration play important roles in the optical, lighting, and energy industries. Herein, a DOPO-based flame retardant 6,6'-((sulfonylbis(4,1-phenylene))bis(oxy))bis(dibenzo[c,e][1,2]oxaphosphinine 6-oxide) with a high transparency and low chromatic aberration was prepared via the classical Atherton-Todd reaction and named SBPDOPO. Its chemical structure was characterized with Fourier IR spectroscopy and NMR spectroscopy. An EP loaded with 7 wt% SBPDOPO passed the UL-94 V-0 rating with an LOI value of 32.1%, and the peak heat release rate, total heat release, and total smoke production were reduced by 34.1%, 31.6%, and 27.7%, respectively, compared with those of pure EP. In addition, the addition of SBPDOPO improved the thermal stability, residual mass, and glass transition temperature of the EP. On this basis, the EP containing 7 wt% SBPDOPO maintained a high transparency and low color aberration, with a transmittance of 94% relative to that of pure EP and a color aberration ΔE of 1.63. Finally, the flame-retardant mechanism of SBPDOPO was analyzed, which demonstrated that it exerted both gas-phase and condensed-phase flame-retardant effects, and that SBPDOPO/EP had high potential for application scenarios in which both flame retardancy and transparency are needed. SBPDOPO/EP has great potential for applications requiring both flame retardancy and transparency.

FUNCTIONAL MATERIALS FROM PAPER WASTES. V. SYNTHESIS AND CHARACTERIZATION OF HYBRID NANOCOMPOSITES OF POWDER CELLULOSES ISOLATED FROM WASTE PAPER AND SILVER NANOPARTICLES

Hybrid nanocomposites of powder celluloses (PCs) isolated from newsprint and cardboard waste containing silver nanoparticles (NPs) were synthesized using the diffusion-reduction method. The reduction of silver from solutions of its salt was carried out under heterogeneous conditions using trisodium citrate as a reducer. Molar ratio (MR) of PC/silver varied from 20 to 40. The mechanism of silver NPs formation and stabilization in the reduction process was considered. The hybrid nanocomposites were studied by IR-Fourier spectroscopy, high-resolution 13С NMR spectroscopy in a solid phase, wide-angle X-ray scattering, scanning electron microscopy (SEM), and energy-dispersive X-ray microanalysis (EDRA). It was shown that the silver particles had spherical shape and their size on the surface of the PC was mostly less than 100 nm. The silver content in the nanocomposites ranged from 1.2 to 7.3 wt.%. The preparation of NPs did not change in the structural modification of cellulose I after the reaction. During the modification of PCs with silver nanoparticles, the cellulose matrix was involved in a redox process, which was accompanied by the formation of new intermolecular bonds between the NPs and the matrix.

Synthesis of cellulose nitrates from Miscanthus × giganteus var. KAMIS cellulose obtained under pilot production conditions

The work is devoted to the study of a novel national raw material resource Miscanthus × Giganteus var. KAMIS, which is positioned as one of the most promising natural sources for obtaining high-quality cellulose for the purpose of its further chemical functionalisation. A batch of technical cellulose isolated from raw materials under pilot production conditions using the nitric acid method having a cellulose content of 50.2% was characterized by high α-cellulose mass fraction (92.8%) and degree of polymerisation (1200) values. On the basis of the pilot batch of technical cellulose, a sample of cellulose nitrates offering basic functional properties was obtained: mass fraction of nitrogen – 11.18%; viscosity – 48 MPa·s; solubility – 94%. The synthesised sample is characterized by extremely high solubility in acetone, confirming the production of cellulose nitric acid esters, and a high yield of 150%. IR-Fourier spectroscopy was used to identify the main functional groups in the experimental batch of technical cellulose (3384, 2902, 1639, 1428, 1370, 1319, 1161, 700–500 cm-1) and in a sample of cellulose nitrates (1659, 1278, 834, 746, 683 cm-1). Acorresponding affiliation to cellulose and cellulose nitric acid esters was established. The structural and morphological features of the fibres of the experimental batch of technical cellulose and a sample of cellulose nitrates were characterised using scanning electron microscopy. Combined methods of thermogravimetric and differential thermal analyses were used to establish high initial temperature (197 °C) and specific heat of decomposition (6.92 kJ/g) values at the beginning of intensive decomposition. The obtained results substantiate the possibility to chemically functionalise cellulose isolated from a new alternative source into cellulose nitric acid esters with satisfactory functional properties.