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Based on the results of mathematical modeling and theoretical research works, it was established that the most influential factors of 3D printing, affecting the quality and time of end products formation, are extruder die temperature, layers height, speed of printing head movement when forming products, as well as simultaneous fabrication of several products within one cycle. In the work, the modes of the FDM 3D printing process were worked out and the regularities of the influence of the mentioned parameters on the structure and properties of resulted 3D polylactide products were established. The parameters of product formation were experimentally determined, which provide the production of 3D objects with predicted properties: maximum strength (98 % of filament strength), high aesthetic quality (surface smoothness and resolution) and products with minimal investments of time during their production. [ABSTRACT FROM AUTHOR]

The work is a study of the influence of mixtures of gaseous hydrogen with natural gas with the ratios of 10 % H2/90 % CH4 and 20 % H2 /80 % CH4 on PE-80 polymer pipes. The paper presents the results of complex structural investigations of the material of polyethylene pipes from pe-80, which were used earlier in the operating gas distribution networks of ukraine, after 6 months of their hydrogenation. The influence of gas mixtures on the material structure was established, which is manifested in reduction of the quantity of the crystalline phase, polyethylene crystallite dimensions and their orderliness. no changes in the chemical structure of the polyethylene pipe material were found. [ABSTRACT FROM AUTHOR]

Welds of polymer materials, butt welded with a heated tool, are distinguished by a variety of structural components. Investigations of such welds allow studying the general fundamental processes of structure formation in the formation of welded joints of polymers. In this work, mechanical tests of welded joints of polymer pipes with a local load in the environment of surface active substances and with the use of the Rehbinder effect were carried out. Experimental specimens of pipe joints with a diameter of 63, 90, 110 and 160 mm from pe80 polyethylene were produced in the standard equipment for butt welding with a heated tool on the modes recommended by DBn v.2.5-41:2009. the tests were carried out in accordance with the requirements of the international standard ISO 22088 "Cracking under the influence of the environment" (ESC). The characteristic features of cracks propagation in the tests of the base material and the fusion zone of the weld were investigated. using optical microscopy, the fracture surfaces of the specimens were investigated immediately after tests and after chemical etching in sulfuric acid solution. It was shown that in the fusion zone, a weakened "blurry" structure of polymer material is formed, which is fractured during a local load. [ABSTRACT FROM AUTHOR]

The process of welding plastics is determined as a gradual disappearance of the interface between parts to be joined and the formation of a transition layer between them, whose structure is significantly different from the structure of the base polymeric material. The models of formation of welded joints of polymers existing today are based on different physical phenomena: mutual adhesion of substrates, diffusion of macromolecules and melt rheology. The most common is the diffusion model of macromolecules reptation in the welding zone, which many researchers refer to in order to explain experimental data. Without denying the possibility of progressive diffusion of elements of the molecular chain through the fusion surface, the postulate that this diffusion provides the main mass transfer during the formation of welded joints of polymers is considered to be controversial. The theory of the formation of welded joints of polymers due to conformational transformations of macromolecule fragments, being developed by the Scientific School of the PWI, is more realistic. In the development of this conformational theory, the model of homogenization of the transition layer on the interface during welding of polymers is proposed based on a vacancy-conformational principle. [ABSTRACT FROM AUTHOR]

In this work, the technology of chemical overlap welding of polymer materials based on epoxy resins (transparent film) and their nanocomposites with oxidized graphene (black film) was developed. The overlap welding of film materials with a thickness of 0.5 mm was carried out under the conditions of isothermal heating of 150 °C and pressure of the limiting plate. The selection of an effective welding mode was performed at different duration of welding: 30 and 60 min. Mechanical tests of the produced welded joints showed their strength at the level of the base material. features of the structural organization of welded joints of composites were investigated by the method of wide-angle X-ray diffraction. the chemical structure of the material of welded joints was investigated by the fourier transmission infrared spectroscopy. Modeling of stresses that occur in the specimens of welded joints was calculated using the values of the modulus of elasticity and the coefficient of linear expansion, experimentally found by the method of thermal mechanical analysis. [ABSTRACT FROM AUTHOR]

Chemical welding as an attractive alternative to classical joining techniques occurs through the formation of new chemical bonds between neighboring molecules at the contacting surfaces to be joined. This review paper presents the current state of the chemical welding of polyurethanes and their composites via dynamic covalent bonds. The strength of welded joints obtained by different welding technologies was compared. Different processing parameters affecting the joint quality, namely welding time and welding temperature were summarized. The future perspectives of chemical welding of polyurethanes and their composites were discussed in the paper. [ABSTRACT FROM AUTHOR]

In the work, a mathematical description of thermal processes in laser welding with the use of the classical theory of thermal conductivity was performed. The thermal cycle under the action of radiation on the surface was analyzed using the models of overall heat balance, distributed surface, point, circular and linear heat sources. The modeling of welding process consisted in solving the problem of forming thermal fields in viscoelastic polymer materials at a moving inner heat source. It was assumed that the upper part is transparent to laser radiation and the lower one has a set coefficient of light beam absorption, and their thermophysical characteristics depend on temperature. The equations of thermal conductivity and defining equations were formulated, supplemented by the boundary conditions of convective heat transfer and the initial temperature distribution. For the numerical implementation of certain equations the finite element method was used, which is based on an alternative formulation of the problem. The results of mathematical modeling showed the peculiarities of the formation of thermal fields in the transmission laser welding of polymer films at different parameters of welding mode. [ABSTRACT FROM AUTHOR]

The addition of silver ions or nanoparticles to impart antimicrobial properties to polymeric or other materials is a widely used method. However, it should be noted that the antiviral and antimicrobial effect of silver nanoparticles that come into contact with the environment, associated with their size, with a decrease in the size of nanoparticles, their effectiveness increases sharply. In the present work, we used a biodegradable polymer polylactide (PLA), which is obtained by condensation of lactic acid or ring-opening polymerization of lactide. These studies will further contribute to the development of new safe materials, in particular for food packaging, which is undoubtedly an urgent problem. The work aims is to obtain the silver-containing polymer composites based on polylactide by thermochemical reduction of Ag+ ions using natural (chitosan) and synthetic (polyethyleneimine (PEI)) polymers and to study the structure, morphology, thermomechanical and antimicrobial properties of the obtained nanocomposites. Thermochemical reduction of Ag+ ions in the bulk of polymer films, containing PLA, silver palmitate as a precursor of Ag NP and reducing agent (PEI or chitosan), has been performed by keeping them at 100–170 °C within 5 minutes. The polymeric film composites, cast from chloroform solution, were heated in an oven using precise thermal regulator VRT-3. As a result of reduction, the films get attained silver color, the Ag content in the bulk of films varied from 1 to 4 wt. %, and the thickness of the films was 110 μm. Structure, morphology, thermomechanical and antimicrobial properties of two types of nanocomposites – PLA-Ag-PEI and PLA-Agchitosan, formed by the thermochemical reduction of Ag+ in polymer films have been studied using wide-angle X-ray scattering (WAXS) (a DRON-4-07 diffractometer), a transmission electron microscope (TEM) (JEM-1230 JEOL, Japan), and thermomechanical analysis (a UIP-70M device). Antimicrobial activity of the obtained nanocomposites was investigated applying reference strains of opportunistic bacteria Staphylococcus aureus and Escherichia coli. It has been found that thermochemical reduction of Ag+ ions in the bulk of polymer films, when using synthetic or natural polymers (PEI or chitosan) as a reducing and stabilizing agent of silver nanoparticles occurs at 160 °C during 5 minutes. It has been found that the average size of Ag nanoparticles in the polymeric matrix is equal to ~ 7 and ~ 4 nm for PEI and chitosan, respectively. It has been shown that PLA-Ag-chitosan nanocomposites have much higher antimicrobial activity against S. aureus and E. coli strains as compared to PLA-Ag-PEI nanocomposites. [ABSTRACT FROM AUTHOR]

Manufacture of parts by the method of 3D printing, in particular, applying FDM (Fusing Deposition Modeling) technology, is a promising trend in many branches of mechanical engineering, architecture, construction, medicine, etc. This range of problems challenges three main directions of studies: FDM 3D printing technology, materials science and mathematical modeling of processes for evaluation of functional qualities, in particular, strength of products. This work is devoted to the third direction: evaluation of stress-strain state of products manufactured by 3D printing using FDM technology. The paper considers three stages of solving this problem: 1 -- mathematical formulation of the problem, which includes universal balance relations, determining equations of mechanical behaviour of the material; 2 -- method of numerical solution of the problem; 3 -- solving specific problems in order to determine patterns of thermomechanical processes and provide recommendations for technological settings of 3D printing. 10 Ref., 12 Figures. [ABSTRACT FROM AUTHOR]

The aim of the work is to test the technology of welding filter bags made of polyester ultralight fabric of linen weaving. The tasks are the choice of welding method, creating an experimental installation, adjusting the parameters of the welding process and evaluating the quality of the produced welds. The method of heat-pulse welding with T-shaped welt seams with continuous penetration and simultaneous cutting of the welded material was chosen. An experimental installation with a heating element made of nichrome wire of 0.8 mm diameter was developed. During one cycle of heat-pulse welding, two longitudinal welds, the so-called T-shaped welt seams are formed, the shape and size of which depend on the heating mode of the polymeric material. Welded filter bags were turned before using in such a way that T-shaped seams in the working environment were directed inwards and the load on dangerous areas of welds was reduced. Mechanical tests of welds of filter polyester fabric produced by heat-pulse welding showed a sufficient level of their mechanical strength. To control the quality of the finished filter bags, it is sufficient to visually inspect the welds for leaks or other obvious defects. Results of the work is the technology of manufacturing filter bags from mesh polyester fabric by means of heat-pulse welding of welt seams with continuous penetration and cutting of the welded material is worked out. The welding installation was created. Parameters of a welding mode were established. It was determined that produced welded joints in terms of strength characteristics meet the necessary criteria for the intended use of filter bags made of ultra-thin polymeric fabrics. [ABSTRACT FROM AUTHOR]

The structure and properties of Cu/Cu2O-containing nanocomposites formed by chemical reduction of Cu2+ ions in interpolyelectrolyte–metal complexes (IMC) at different molar ratios [NaBH4]: [Cu2+] and reduction times were studied by methods of wide- and small-angle X-ray scattering, transmission electron microscopy, thermomechanical analysis, and antimicrobial tests. Optimal conditions ([NaBH4]: [Cu2+] = 6.0, reduction time ≥ 120 min) for the formation of copper-containing nanocomposites based on interpolyelectrolyte complexes and Cu/Cu2O core–shell nanoparticles have been established by X-ray diffraction analysis. Owing to the above conditions, the structural manifestation of the metal copper phase is fully realized. Applying transmission electron microscopy, it was found that at molar ratio [NaBH4]: [Cu2+] = 6.0, and reduction time of 40 min and 180 min, accordingly, the nanocomposites with average nanoparticles size of 4.1 nm and 12.4 nm are derived from IMC, respectively, what correlates with effective size of the nanocomposites' heterogeneity regions, lp. Thermomechanical analysis has shown that raise in the amount of reducing agent or the duration of reduction of Cu2+ ions in IMC is accompanied by elevation in the glass transition temperature, which reaches a constant level, boost in the temperature of transition to the viscous state Tf and decrease in the relative deformation of nanocomposites. The antimicrobial investigations of the elaborated nanocomposites revealed they possess an antimicrobial activity against S. aureus and E. coli strains. [ABSTRACT FROM AUTHOR]

The structure and properties of silver-containing nanocomposites formed by the method of thermochemical reduction of Ag+ ions in polyelectrolyte-metal complexes pectin–Ag+–polyethyleneimine were studied using X-ray diffraction analysis, thermogravimetric analysis, pyrolysis mass spectrometry, transmission electron microscopy and antimicrobial test. The optimal parameters for the formation of nanocomposites based on interpolyelectrolyte complexes of pectin–polyethyleneimine and Ag nanoparticles (reduction temperature T = 150 °C, reduction time t = 30 min) have been found by X-ray diffraction analysis, in which the structural manifestation of the silver metal phase is fully realized. Using transmission electron microscopy, it was found that nanocomposite formed by thermochemical reduction of Ag+ ions at 150 °C for 30 min has an average nanoparticle size of 4.1 nm that less than for nanocomposite obtained at T = 120 °C during the same reduction time (average nanoparticle size is 5.8 nm). Ag nanoparticles obtained by using a typical reducing agent (NaBH4) have an average size equals 3.8 nm. It was revealed that nanocomposites obtained by thermochemical method have significantly higher antimicrobial activity compared with nanocomposites obtained by chemical reduction of Ag+ ions using NaBH4. A mechanism of thermochemical reduction of silver ions in IMC pectin–Ag+–polyethyleneimine, which is based on the transfer of electrons from the nitrogen atoms of amino groups PEI to Ag+ ions, has been investigated by destructive processes that occur at the same time. [ABSTRACT FROM AUTHOR]

Polyethylene raw materials used for production of polyethylene pipes are constantly being improved. At the beginning of the construction of plastic pipelines, the so-called low pressure polyethylene, currently known as PE-63 grade was used. Subsequently, new, more advanced types of raw materials, which represent a copolymer of polyethylene with hexane, were developed. Today, almost all pressure pipes are made of PE-80 and PE-100 grades of polyethylenes. However, during the repair and reconstruction of plastic pipelines, there is an urgent problem of joining pipes of PE-63, which have been operated for a long time, with new pipes made of polyethylenes of grades PE-80 and PE-100. In the paper, complex investigations of thermophysical properties of technical polyethylenes were carried out and significant differences were revealed, which should be taken into account during the repair of polymer pipelines. Experimental welding of pipe specimens from both single- as well as different-type polyethylenes was carried out. Morphological and mechanical studies of welded joints of polyethylene pipes of grades PE-63, PE-80, and PE-100 were performed. According to the results of investigations, the influence of their thermophysical properties and parameters of the welding process on the morphological structure and quality of welded joints of different-type polyethylenes was determined. Mathematical modeling of temperature fields during butt welding was carried out. A two-zone heating tool for butt welding of pipes with an outer diameter of up to 110 mm of different-type polyethylenes of pipe grades PE-63 and PE-80, PE-100 using a heated tool was designed and created. In order to test an experimental specimen of a two-zone heating tool, a series of experiments were carried out, which showed an improvement in the strength characteristics of the produced welded joints. 8 Ref., 4 Tables, 10 Figures. [ABSTRACT FROM AUTHOR]

Technical laminated fabrics, which are used for the manufacture of awnings and inflatable products for different purposes, are made with double-sided PVC coating. The most widespread practical method of manual and mechanical welding of laminated fabrics with PVC coating is hot air welding. In this work, the features of hot air welding of the overlap welds of laminated PVC fabric were investigated in the manufactured experimental set up. The geometric dimensions and shape of the produced experimental welds from laminated fabric Unisol 950 (specific weight of 950 g/m²) were established. In the course of the work, the mechanical strength of the welds produced by experimental welding was investigated, as well as tear test of the welds was carried out. The range of welding speed was set, within which welded joints of the laminated fabric are formed with tight penetration. It is shown that a tight penetration along the entire plane of the welded joint is achieved by forming a bead of molten PVC, uniform as to its diameter, under the pressure roller in the welding process. The nature of running of thermal processes in the welding zone was evaluated by the geometric parameters of the melt bead. The optimal parameters of the process of producing the butt welds of laminated fabrics, joined by a tape on both sides, and visual criteria for sound joint formation were determined, and the principles of manual control of the hot air welding process in real time were developed. 4 Ref., 10 Figures. [ABSTRACT FROM AUTHOR]

The paper gives the analysis of the state of the art of 3D technologies of polymer materials, which is based on publications presented both in open sources as well as in a wide range of scientific and technical journals, including the own experience of the authors in 3D printing using thermoplastic and thermosetting polymers. The history of additive technologies, state of the art and trends of the development of the market of three-dimensional printing are considered. The classification of the most widespread in the world technologies of additive manufacturing of products from polymer materials depending on the methods of processing plastics is offered, their short description is given, their features, advantages and disadvantages are presented. 27 Ref., 1 Table, 6 Figures. [ABSTRACT FROM AUTHOR]

The volume of polymer composite structures in the aircraft industry is steadily increasing. Polymer composites based on thermosetting matrices are traditional in this field, but it is important to use new thermoplastic composites (TPCs), which have several advantages over thermosetting ones. The use of thermoplastic composite materials makes it possible to actively use welding processes in the production of structures, which significantly increases the productivity of work and reduces their cost. In the aircraft industry 3 types of heat-resistant polymers of the class of polyarylene are mostly used: polyetheretherketones (PEEK and PEKK), polyetherimide (PEI) and polyphenylene sulfide (PPS). Aeronautical structures are characterized by a large variety and complexity of forms, that's why almost all known methods of plastic welding are involved for joining. The resistance welding of polymer materials applying embedded elements made of metal mesh or carbon fabric is actively used. Induction welding technology is suitable for joining structures made of conductive carbon composites. Ultrasonic welding, laser welding, and indirect-heated tool welding are also used in aircraft engineering. Nowadays, welding processes are usually digitally controlled with permanent data storage, but currently the agenda is to move to linear process control using temperature monitoring. This paper, based on the materials of European publications, presents examples of the application of different welding methods in the manufacture of structures made of modern polymer thermoplastic composites in the aircraft industry. 16 Ref., 9 Figures. [ABSTRACT FROM AUTHOR]

The purpose of this study was investigation of the polymer composites based on the aliphatic epoxy oligomer - diglycidyl ether of polyethylene glycol DEG-1, aromatic diane-epoxy resin DER-331 and different content of the perchlorate lithium salt. Structure and properties of composites were characterized by means of the wide angle X-ray scattering (WAXS), the thermogravimetric analysis (TGA), the differential scanning calorimetry (DSC) and the broadband dielectric spectroscopy (BDS). The results show that the synthesized composites based on the aliphatic and aromatic oligomers in the presence of lithium perchlorate salt are amorphous with the ionic conductivity ~ 4H10'4 S/cm at 200 °C. An increase of the glass transition temperature of the synthesized composites has been observed with increasing of the salt concentration that indicates the influence of lithium perchlorate on the molecular structure of composites. [ABSTRACT FROM AUTHOR]

The dependencies of creep and mechanical relaxation, elongation and stress/strain function, elasticity modulus at elongation and pressure on the chemical composition of organic component of OIS based on oligoetherurethane, polyisocyanate with low molecular weight, and metal silicate were investigated. A good correlation between changes of mechanical parameters and structure of hybrid organic-inorganic network, which is formed during synthesis of OIS have been established. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic systems (OIS) based on urethane oligomers with different molecular weight and sodium silicate were synthesized. Comparing of the diffusion parameters of OIS and respective polyurethanes shows that water-absorbing properties of OIS are determined by the presence of hydrophilic inorganic phase, where stabilization of the incoming sorbate (water) takes place. Organic polymer matrix of OIS does not limit the water-incoming rate and diffusion constant value depends on conditions of water stabilization in the inorganic phase. OIS-2102 possess the highest sorption capacity due to the high molecular weight of respective OPG and its linear structure. [ABSTRACT FROM AUTHOR]

Electrothermal processes were studied in pyroresistive composites based on high-density polyethylene (HDPE) containing 8 vol.% carbon black (CB), 8 vol.% carbon fibers (CF), and their mixture 4 vol.% CB + 4 vol.% CF. It is shown that the kinetic heating curves of composites are well described by an exponential dependence with a certain heating rate constant k for each type of composite. After a short heating time, the equilibrium temperature T e is reached in the sample. When the applied voltage exceeds a certain value, the T e value decreases due to the presence of the positive temperature coefficient of resistance (PTC) effect. Due to the PTC effect, the composites exhibit a self-regulating effect relative to the T e . Relations between the applied voltage, electric power, and equilibrium temperature are found, the T e value depends on the applied voltage according to the quadratic law whereas there is a linear relationship between the T e and electric power. A possible application of such pyroresistive composites is resistance welding of plastics using a heating element (HE) made of a pyroresistive material. The use of HDPE-CB composite to create HE for resistance welding is demonstrated and the welded joint of HDPE parts obtained using HE is shown.

One of the most important directions in the development of additive manufacturing or three-dimensional (3D) printing technologies is the creation of functional materials, which allow not only prototyping but also the manufacturing of products with functional properties. In this paper, poly-lactide acid (PLA) /carbon black (CB) composites with segregated (ordered) structure have been created. Computer simulation based on the Mamunya geometrical model showed that the CB content within φ = 2.5-5 vol.% in the polylactide matrix leads to the formation of a continuous electrically conductive phase with an increase of electrical conductivity σ dc above the percolation threshold. The simulation results were experimentally confirmed by optical microscopy and studies of the electrical conductivity of the composites. It was found that increasing CB content from φ = 1 vol.% to φ = 7 vol.% in the composites causes insignificant (due to the segregated structure) phase changes in the polylactide matrix and improves the thermal properties of composites. Electrically conductive filaments for Fused Deposition 3D Printing (FDM) were developed from PLA/CB composites and then 3D printed. A correlation between the electrical conductivity σ dc and the CB content φ for base composites, filaments produced from them, and final 3D samples, has been found. Conductivity varies within σ dc = 3.1·10 -11 - 10·10 -3 S/cm for the filaments and σ dc = 3.6·10 -11 - 8.1·10 -4 S/cm for the final 3D-products.

Antimicrobial and antiviral nanocomposites based on polylactic acid (PLA) and chitosan were synthesized by a thermochemical reduction method of Ag + ions in the PLA-Ag + -chitosan polymer films. Features of the structural, morphological, thermophysical, antimicrobial, antiviral, and cytotoxic properties of PLA-Ag-chitosan nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and antiviral, antimicrobial, and cytotoxic studies. The effects of temperature and the duration of reduction of Ag + ions on the structure of PLA-Ag-chitosan nanocomposites were established. During the thermochemical reduction ( T = 160 °C, t = 5 min) of silver palmitate ions in PLA-Ag + -chitosan polymer films, Ag nanoparticles with an average size of 4.2 nm were formed. PLA-Ag-chitosan polymer nanocomposites have strong antimicrobial activity against S. aureus and E. coli strains. In particular, for PLA-chitosan samples containing 4% Ag, the diameters of the S. aureus and E. coli growth inhibition zones were 25.8 and 25.0 mm, respectively. The antiviral activity of the nanocomposites against influenza A virus, herpes simplex virus type 1, and adenovirus serotype 2 was also revealed. The PLA-4%Ag-chitosan nanocomposites completely inhibited the cytopathic effect (CPE) of herpes virus type 1 by 5.12 log 10 TCID 50 /mL (high antiviral activity) and the development of the CPE of influenza virus and adenovirus by 0.60 and 1.07 log 10 TCID 50 /mL (relative antiviral activity). The obtained nanocomposites were not cytotoxic; they did not inhibit the viability of MDCK, BHK-21, and Hep-2 cell cultures.

Green synthesis of silver-containing nanocomposites based on polylactide (PLA) was carried out in two ways. With the use of green tea extract, Ag + ions were reduced to silver nanoparticles with their subsequent introduction into the PLA (mechanical method) and Ag + ions were reduced in the polymer matrix of PLA-AgPalmitate (PLA-AgPalm) (in situ method). Structure, morphology and thermophysical properties of nanocomposites PLA-Ag were studied by FTIR spectroscopy, wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) methods. The antimicrobial, antiviral, and cytotoxic properties were studied as well. It was found that the mechanical method provides the average size of silver nanoparticles in the PLA of about 16 nm, while in the formation of samples by the in situ method their average size was 3.7 nm. The strong influence of smaller silver nanoparticles (3.7 nm) on the properties of nanocomposites was revealed, as with increasing nanosilver concentration the heat resistance and glass transition temperature of the samples decreases, while the influence of larger particles (16 nm) on these parameters was not detected. It was shown that silver-containing nanocomposites formed in situ demonstrate antimicrobial activity against gram-positive bacterium S. aureus , gram-negative bacteria E. coli , P. aeruginosa , and the fungal pathogen of C. albicans , and the activity of the samples increases with increasing nanoparticle concentration. Silver-containing nanocomposites formed by the mechanical method have not shown antimicrobial activity. The relative antiviral activity of nanocomposites obtained by two methods against influenza A virus, and adenovirus serotype 2 was also revealed. The obtained nanocomposites were not-cytotoxic, and they did not inhibit the viability of MDCK or Hep-2 cell cultures.

The article is concerned with hybrid amorphous polymers synthesized basing on epoxy oligomer of diglycide aliphatic ester of polyethylene glycol that was cured by polyethylene polyamine and lithium perchlorate salt. Structural peculiarities of organic-inorganic polymer composites were studied by differential scanning calorimetry, wide-angle X-ray spectra, infrared spectroscopic, scanning electron microscopy, elemental analysis, and transmission and reflective optical microscopy. On the one hand, the results showed that the introduction of LiClO 4 salt into epoxy polymer leads to formation of the coordinative metal-polymer complexes of donor-acceptor type between central Li + ion and ligand. On the other hand, the appearance of amorphous microinclusions, probably of inorganic nature, was also found.

The paper presents results of the investigation of structure relaxation and thermal properties of PE-80 and PE-100 polyethylene hot-tool butt welds. It was found that a weld with the re-crystallized crystalline structure is formed during the welding of dissimilar types of polyethylene. It is shown that within a long period (1 year) the relaxation occurs not only in amorphous but also in the crystalline phase (crystalline α-form transforms into mixed αβ-form), with respective changes in polyethylene properties.

As it is known, polyethylene (PE) is one of the common materials in the modern world, and PE products take the major share on industrial and trade markets. For example, various types of technical PE like PE-63, PE-80, and PE-100 have wide industrial applications, i.e., in construction, for pipeline systems etc. A rapid development of plastics industry outstrips detailed investigation of welding processes and welds' formation mechanism, so they remain unexplored. There is still no final answer to the question how weld's microstructure forms. Such conditions limit our way to the understanding of the problem and, respectively, prevent scientific approaches to the welding of more complicated (from chemical point of view) types of polymers than PE. Taking into account state-of-the-art, the article presents results of complex studies of PE weld, its structure, thermophysical and operational characteristics, analysis of these results, and basing on that some hypotheses of welded joint and weld structure formation. It is shown that welding of dissimilar types of polyethylene, like PE-80 and PE-100, leads to the formation of better-ordered crystallites, restructuring the crystalline phase, and amorphous areas with internal stresses in the welding zone.

In the present work, ion-conductive hybrid organic-inorganic polymers based on epoxy oligomer of diglycide aliphatic ester of polyethylene glycol (DEG) and lithium perchlorate (LiClO4) were synthesized. The effect of LiClO4 content on the electrophysical properties of epoxy polymers has been studied by differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The effect of LiClO4 content on the structure has been studied by wide-angle X-ray scattering (WAXS). It was found that LiClO4 impacts on the structure of the synthesized hybrid epoxy polymers, probably, by formation of coordinative complexes {ether oxygen-lithium cations-ether oxygen} as evidenced from a significant increase in their glass transition temperatures with increasing LiClO4 concentration and WAXS studies. The presence of ether oxygen in DEG macromolecules provides a transfer mechanism of the lithium cations with the ether oxygen similar to polyethylene oxide (PEO). Thus, the obtained hybrid polymers have high values of ionic conductivity σ' (approximately 10(-3) S/cm) and permittivity ϵ' (6 × 10(5)) at elevated temperatures (200°С). On the other hand, DEG has higher heat resistance compared to PEO that makes these systems perspective as solid polymer electrolytes able to operate at high temperature., Pacs: 81.07.Pr; 62.23.St; 66.30.hk.

The relaxation processes of hybrid organic-inorganic polymer nanosystems (OIS) synthesized by joint polymerization of organic and inorganic components were studied using methods of differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and broadband dielectric relaxation spectroscopy (DRS). The organic component was a mixture of two products: high-molecular-weight macrodiisocyanate (MDI) with low reactivity and low-molecular-weight isocyanate-containing modifier poly(isocyanate) (PIC) with high reactivity. Sodium silicate (SS) was used as inorganic component. The structures of the OIS obtained were in the form of hybrids with covalently connected building blocks and interpenetrating networks: weakly cross-linked network MDI/SS and highly cross-linked network PIC/SS. Depending on the MDI/PIC ratio, one of the networks was prevailing and created a continuous structure with domains of second network., Pacs: 61.25.hk; 82.35.Lr; 64.70.pj.