Structure Of Polymer Composite Materials Research Articles

Features of application of adaptive interferometric fiber sensors of acoustic emission to monitor the condition of polymer composite materials

The results of an experimental study of the operation of fiber optic sensors (FOS) of acoustic emission introduced into the structure of polymer composite materials (PCM) are presented. The reliability and fault tolerance of FOS under critical mechanical loads on PCM was assessed, and the influence of the presence of FOS embedded into the structure of PCM on the mechanical characteristics of the material was investigated. For demodulation of FOS output signals, the principles of adaptive holographic interferometry based on two-wave mixing at dynamic hologram formed in a photorefractive crystal are used.

Research of Moisture Sorption by Laminated Composite Materials

This article focuses on the moister sorption by laminated composites. Moisture sorption was carried out on layered polymer composite materials consisting of layers of basalt fabric and fiberglass based on epoxy-diane resin. It is shown that the process of moisture absorption for glass fiber-reinforced polymers is more intense and with a higher concentration of moisture in comparison with basalt fiber-reinforced polymer. Curves of the sorption processes of moisture absorption and water absorption are obtained. The diffusion coefficients for the corresponding processes are calculated. Alteration in the surface structure of polymer composite materials were recorded using surface topography and REM images before and after exposure in the climate of Yakutsk (Russia).

Влияние ультразвуковых колебаний с наложенной низкочастотной модуляцией на механические, трибологические свойства и структуру многокомпонентного полимерного композита

One of the tasks of polymer materials science is to study the possibilities of improving the complex of elastic-strength characteristics and tribological properties of polymer composite materials by improving the manufacturing technology. In this paper, the influence of ultrasonic vibrations with a frequency of 17 kHz with a low-frequency vibration with a frequency of 100 Hz during synthesis on the properties and structure of a multicomponent polymer composite material of the KVN-3 trademark is considered. The result of the research, it is found that the influence of the technological mode of pressing, consisting in the combined effect of ultrasonic vibrations with frequency and low-frequency vibration during the synthesis of KVN-3, makes it possible to increase the complex of elastic-mechanical characteristics: tensile strength by 3 %, elongation by 6 %, modulus of elasticity by 10 %, hardness by 2 %, compared to the industrial manufacturing method, as well as to reduce the intensity of mass wear by 68 % and the coefficient of friction by 3 %. The structure of polymer composite materials after different technological pressing modes is examined. The fibrillar structure of the polymer matrix after the technological regime with the influence of ultrasonic vibrations and low-frequency modulation becomes finer and more uniform.

О СПОСОБЕ ОПРЕДЕЛЕНИЯ СТРУКТУРЫ ПОЛИМЕРНЫХ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ

An alternative method for determining the structure of polymer composite materials is proposed. This method is based on the complex use of physical, mechanical and spectral methods of analysis

Effect of molybdenum disulphide and carbon fibers on the properties and structure of polymer composite materials based on polytetrafluoroethylene

Effect of molybdenum disulphide and carbon fibers on the properties and structure of polymer composite materials based on polytetrafluoroethylene

Study of properties of acrylic, epoxy and epoxy acrylic compositions structured by the methods of convection heating and heating in the field of high-frequency current

This work is devoted to the development and study of the processes of accelerated structuring of polymer composite materials in the field of high-frequency current (microwave field) which are used in the electronic and instrument-making industries, etc. The complex of properties and the features of structuring of epoxy, acrylic and epoxy acrylic polymer composite materials in the microwave field are investigated. In comparison with the traditional method of structuring and polymerization (convection heating), the structuring in the microwave field equally affects the properties of the studied polymer composite materials, regardless of the chemical nature of the oligomer. The action of the microwave field for all studied polymer composite materials causes an increase in the degree of conversion of binders and a decrease in the content of residual monomer (methyl methacrylate) in thermoplastic acrylic polymer composite materials. In addition, the microwave treatment provides the completeness of chemical and physicochemical processes of the formation of rational structure of polymer composite materials with stable properties. The conducted research allows recommending various regimes of the structuring of the studied polymer composite materials taking into account operating conditions. These regimes ensure the reduction of structuring duration and provide a high level of mechanical and operational properties.

UHMWPE/CaSiO3 Nanocomposite: Mechanical and Tribological Properties.

This paper studied the effect of additives of 0.5–20 wt.% synthetic CaSiO3 wollastonite on the thermodynamic, mechanical, and tribological characteristics and structure of polymer composite materials (PCM) based on ultra-high-molecular weight polyethylene (UHMWPE). Using thermogravimetric analysis, X-ray fluorescence, scanning electron microscope, and laser light diffraction methods, it was shown that autoclave synthesis in the multicomponent system CaSO4·2H2O–SiO2·nH2O–KOH–H2O allows one to obtain neeindle-shaped nanosized CaSiO3 particles. It was shown that synthetic wollastonite is an effective filler of UHMWPE, which can significantly increase the deformation-strength and tribological characteristics of PCM. The active participation of wollastonite in tribochemical reactions occurring during friction of PCM by infrared spectroscopy was detected: new peaks related to oxygen-containing functional groups (hydroxyl and carbonyl) appeared. The developed UHMWPE/CaSiO3 materials have high wear resistance and can be used as triboengineering materials.

Research of the endurance of epoxy composite materials under cyclic compression

The widespread use of polymer composite materials is largely constrained by the complexity of predicting the characteristics of their stress-strain state under cyclic types of loading. Due to the poor knowledge of the behavior of polymer composite materials under this kind of loading. At present, it is rather difficult to predict the durability of polymer composite materials under static types of loading, and the available methods for materials of a crystalline structure and polymers are not always applicable to them. Insufficient theoretical and experimental data on the assessment of the stress-strain state of polymer concretes under prolonged loading. Under long-term action of cyclic loads, changes in the structure of polymer composite materials occur due to local self-heating at the tops of growing submicrocracks and the associated change in the elastic-hesteretic properties of the material. In this case, the energy of fatigue manifests itself, when the simultaneous multifactorial cyclic action of natural and force stresses leads to an effect that exceeds the total action of certain types of stresses. And, if such processes have been sufficiently studied for wood, a natural polymer material, then for artificial conglomerates, such as polymer composites, these issues require careful study. Studies of the endurance of epoxy polymer concretes were carried out on samples of prisms 100x100x400 mm according to the method developed by the authors. The formula was used to determine the minimum number of samples required to build endurance lines. The value of the cycle asymmetry coefficient was taken equal to 0.6. The value of the maximum cyclic loading was taken from 0.62 Rв with a gradual decrease. The values of the endurance limit of an epoxy composite material under cyclic loading Rв,pul = 0.43 Rв or 93.72 MPa were obtained, which makes it possible to judge the sufficient durability of this material.

ИДЕНТИФИКАЦИЯ ИСТОЧНИКОВ АКУСТИЧЕСКОЙ ЭМИССИИ В ПОЛИМЕРНОМ КОМПОЗИЦИОННОМ МАТЕРИАЛЕ В УСЛОВИЯХ ЦИКЛИЧЕСКОГО РАСТЯЖЕНИЯ

The structure of polymer composite materials (PCM) provides high mechanical properties but, at the same time, is highly sensitive to the formation of internal defects. Therefore, when designing, manufacturing products, and assessing their reliability in service, much attention is paid to the methods of non-destructive testing, among which the method of acoustic emission (AE) has proven itself to study structural changes in material under external influence. The paper deals with the identification of typical damages in fiberglass samples made of T11-GVS9 glass fiber cloth and DION 9300 FR binder and tested under cyclic tension using the AE method. In the work, the authors solved the problem of selecting the AE informative parameters and used a clustering method to identify the nature and the formation kinetics of the AE sources. The authors performed clustering using the Kohonen self-organization map (SOM) with the Fourier spectra calculated for the AE signals recorded during cyclic tests. Based on the peak frequencies analysis of the produced clusters, the researchers determined their nature and calculated the periods of critical accumulation. When characterizing the AE sources, the authors used the peak frequencies analysis of the wavelet spectra performed for different levels of decomposition. The authors determined the damage accumulation stages of samples during testing based on own research and research by other authors’ results. The study established that registration of AE signals identified as adhesion failure can be used to identify the onset of the material destruction and characterized the local formation of micro-damages in the matrix and fracture of fibers can be used to predict the destruction of PCM.

Service Properties of Composites with Various Types of Hybrid Matrices

Polymer composite materials (PCMs) with a hybrid matrix, which increases the deformation properties of structures in specified local zones, are described. The technology of manufacturing PCMs based on basalt and carbon-filled plastic with various modifiers of a hybrid matrix is ​​described. The structure of PCMs with various hybrid matrix modifiers is ​​estimated. The results of determining the deformation properties of PCMs with various hybrid matrix modifiers using dynamic mechanical analysis are presented. The effect of hybrid matrix modifiers on the glass transition temperature of PCM is revealed. The hybrid matrix modifier having the best characteristics is found.

The Development of Natural-Like Polymer Composite Materials with Liquid Matrix and Their Use in Mechanical Engineering

The prospects for the use of natural-like polymer composite materials (PCMs) in various industries are reviewed in this work. A method for the preparation of PCMs with a liquid matrix is described. The results of mechanical tests of PCMs with a liquid matrix are presented. The materials that may be used as a liquid matrix are proposed. The structure of PCMs with a liquid matrix based on various materials is studied. A relationship between the structure of PCMs with a liquid matrix and the wetting contact angle of a liquid phase material is found.

Main Directions for Research on the Development of Tribotechnical Composites Used in the Arctic Regions (Experience of North-Eastern Federal University in Yakutsk)

Materials science studies the relationship between the structure and properties of materials and their changes under external impacts, and it belongs to the priority domains of science and technology. The creation of new materials, improvement of existing materials, and development of efficient technologies for their processing are the main goals of materials science. Today a substantial number of new metal alloys with special properties, different composites, ceramics, polymers, nanostructured functional powder and synthetic superhard materials, multifunctional coatings, etc., have been designed for various economic activities. But the creation of materials and technologies remains an urgent need because of the progressive development of manufacturing which requires adaptive properties of materials and technologies for their processing. This review analyzes the directions of research at North-Eastern Federal University in the field of tribotechnical materials for use in the Arctic regions. The main areas of research are identified, namely, development of new technologies of production of polymer composite materials (PCM) and improving their performance properties. The prospects of physical processing and chemical modification of the polymer matrix surface are shown. Physicomechanical and tribotechnical properties of antifrictional PCM are discussed. The results of the main theoretical generalizations in the field of analysis of PСM supramolecular structures are presented: (1) effects of critical filler concentrations on the structure and properties of PCM; (2) hypothesis of the nature of intermolecular interaction between the filler and the polymer. The modern trends of scientific investigation are shown, one of which is tribooxidative processes in PCM. The specific development of scientific knowledge and the use of polymers for the northern regions are revealed.

Development of Polymer Composite Materials Based on Ultrahigh-Molecular Weight Polyethylene and Carbon Fillers

The present study investigates the influence of carbon fibers of LO-1-12N/40 brand and modified carbon fibers of "Belum" brand on performance properties and structure of polymer composite materials based on UHMWPE of Gur-4150 grade. It has been established that introduction of both modified carbon fibers and LO-1-12N/40 carbon fiber in an amount of from 1 to 10 wt.% into the polymer matrix does not lead to significant changes in stress-strain properties of composites compared to the starting polymer. It is shown that the wear resistance of the obtained materials is significantly increased when filling with 5 wt.% carbon fibers of "Belum" brand. The rate of mass wear of polymer composite materials is reduced by 3.3 times; the friction coefficient of PCM is lowered by 3.5 times relative to the starting polymer.

Main directions for research on the development of tribotechnical composites used in the Arctic regions (On the experience of North-Eastern Federal University in Yakutsk)

Material science studies the relationship between materials structure and properties and its changes under external influence, and belongs to the priority domains of science and technology. The creation of new materials and also its performance improvement, efficient technologies for their processing is the main goal of material science. Today a substantial number of new metal alloys with special properties, different composites, ceramics, polymers, nanostructured functional powder and synthetic superhard materials, multifunctional coatings, etc. have been designed for various economic activities. But the creation of materials and technologies remains an urgent need, because of the progressive development of manufacturing which requires adaptive materials properties and technologies for their processing. This review analyzesAmmosovNorth-EasternFederalUniversity research directions in the field of tribotechnical materials for use in the Arctic regions. Main areas of research are identified, such as developing of polymer composite materials (PCM) production and improving their performance properties. The prospects of physical processing and chemical modification of the polymer matrix surface are shown. Physicomechanical and tribotechnical properties of antifrictional PCM are discussed. The results of the main theoretical generalizations in the field of analysis of PСM supramolecular structures are presented: 1) effects of critical filler concentrations on the structure and properties of PCM; 2) hypothesis of the nature of intermolecular interaction between the filler and the polymer. The modern tendencies of scientific investigation are shown, namely tribooxidative processes in PCM. The specific development of scientific knowledge and the use of polymers for the northern regions are revealed.

Исследование влияния механоактивации на свойства и структуру полимерных композиционных материалов на основе политетрафторэтилена и вермикулита

Исследование влияния механоактивации на свойства и структуру полимерных композиционных материалов на основе политетрафторэтилена и вермикулита

Radiation-Modification Impact on the Filled Polytetrafluoroethylene Structure and Mechanical Strength

The article studies the structure and properties, regularities of their change with the introduction of various fillers and under the influence of gamma – irradiation (γ-radiation). PCM structure study was performed using electron microscopy with scanning electron microscope BS -350 (TESLA) and with X-ray structural analysis method using X-ray diffractometer DRON-3. Shooting of wide-angle X-ray patters was performed in the range of Bragg angles reflection 2Q=5° - 96°. We selected the following properties to study: tensile strength, static tensile modulus. The findings allowed determining: firstly, we determined that based on electron microscopy the supramolecular structural organization depends on the type and percentage of filler in PTFE matrix. Changes take place from lamellar (pure PTFE) to a defective spherulitic (20% of coke) structure. Secondly, we completed X-ray structural analysis (we determined the degree of crystallinity, crystallite size, with parameters а = b in the hexagonal cell, interlayer distance of amorphous area) showed the nature of supramolecular structure changes according to the nature of the filler and subsequent radiation dose. Thirdly there was conducted connection between changes in mechanical strength (tensile strength, statical module of elasticity) and structural changes; the depth of these changes depends on the original supramolecular structure, type and percentage of the filler and the dose of the absorbed radiation energy. The studies will allow change purposefully the supramolecular structure of polymer composite materials to improve the performance properties.

Acoustic-emission evaluation of the process of destruction of a composite material under tensile, compression, and cyclic loads

Destruction of the structure of polymer composite materials (PCMs) has been studied by acoustic-emission evaluation method under tensile, compression, and alternating-sign cyclic loads. A program of cluster classification of registered data arrays has been developed and used to reveal specific AE signals that are typical of studied load types. Detection of such signals in the course of deformation of the test samples indicates that irreversible structural changes occur in the composite, it is losing its carrying capacity, or a predestruction state that is critical for PCM has been reached.

Investigation of the properties of filled polyethylene by the texture pattern of macrostructure images

The results of an investigation of the structure of polymer composite materials are presented. The materials were produced with the use of the texture analysis and mathematical methods of processing of macrostructure images. The approach proposed to measure texture parameters allows one to investigate the effect of the type and concentration of the filler on the properties of the material.