scholarly journals RESEARCH OF ADHESIVE AND HEAT-PROTECTIVE PROPERTIES OF RUBBERS BASED ON EPDM WITH ARAMID FILLER

2020 ◽  
pp. 53-61
Author(s):  
Galina Shaydurova ◽  
◽  
Dmitriy Oros ◽  
Natalya Povarnitsyna ◽  
◽  
...  
Keyword(s):  
Adhesive Strength ◽  
Thermophysical Properties ◽  
High Speed ◽  
Phenol Formaldehyde ◽  
Experimental Studies ◽  
Practical Significance ◽  
Laboratory Research ◽  
Formaldehyde Resin ◽  
Ethylene Propylene ◽  
Vulcanized Rubber

Reinforced materials of the "fabric filler-vulcanized rubber" type may be successfully operated under the condition of the specified adhesive strength at the interface of the "substrate-polymer (rubber) "contact. The article presents theoretical infor-mation about ethylene propylene (EDM) and ethylene-propylene-diene (EPDM) synthetic rubbers, known internationally under the brand name EPDM-monomer, arimide fiber and laboratory research methods. The advantages of using EDM and EPDM in the manufacture of heat-protection coatings are; high heat resistance, low density, good compatibility with fillers (mineral and synthetic), compatibility with epoxy and phenol-formaldehyde resins, belong to coking materials. The article also provides the results of experiments and analysis of the data obtained, namely, the adhesive strength and thermal effect of rubbers based on EPDM with an arimide filler of a non-woven structure. The object of the research was modified heat-protective materials based on EPDM, and the subject of the research was selected rubber compounds based on EPDM and synthetic arimide fiber. To as-sess the physicochemical and thermophysical properties, a derivatographic analysis was performed, which includes TGA and DTA, two vulcanized rubber-woven samples from rubbers of grades 51-1615, 51-2110 together with arimide fiber. For the first time, results were obtained using ethylene-propylene-diene rubbers, including modification with a phenol-formaldehyde resin, which gives a higher erosion resistance when exposed to high-speed heat flow. Analysis of the results of experimental studies has shown that the use of arimide fiber can provide higher strength and thermophysical properties of heat-protective materials. In general, the results obtained may be of practical significance for the development of new-generation products.

scholarly journals Fire risk of hull structures made of polymeric composites and ways to mitigate it

2021 ◽  
Vol 2 (396) ◽  
pp. 73-84
Author(s):  
S. Borodai ◽  
◽  
S. Kozlov ◽  
A. Letin ◽  
L. Rozum ◽  
...  
Keyword(s):  
Fire Protection ◽  
High Speed ◽  
Fire Hazard ◽  
Experimental Studies ◽  
Thermal Characteristics ◽  
Fire Risk ◽  
Practical Significance ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Under Construction

Object and purpose of research. The object of the study is polymer composite materials (PCM) used for manufac-turing hull structures of ships and vessels. The main purpose is to find the ways of fire protection of ships and vessels built from these materials. Materials and methods. The results of experimental studies and standard tests on the fire resistance of PCM structures, as well as methods of heat and mass transfer processes simulation in ship premises during fires, were used to determine the thermal characteristics affecting these structures. Main results. The ways of improving the fire safety of ships and vessels with PCM hull structures are determined. The list of problems to be solved in this area is outlined. Also this study has recommendations to improve the fire protection of the ships being designed, under construction and in operation. Conclusion. The structural PCM used in indigenous practice does not meet the current requirements of the International Maritime Organization (IMO) for Maritime Safety for fire protection of high-speed vessels and the requirements for fire protection of Navy ships. Ships that are in service and built using these materials do not provide additional measures to reduce their fire hazard. Fires on such ships can lead to disastrous consequences. It is necessary to solve this problem as soon as possible. The recommendations proposed in this paper on how to solve it, based on a large amount of experimental research, and they have great practical significance.

scholarly journals Comparative analysis of variants of magnetic pole collection based on the halbach massif

2017 ◽  
Vol 3 (1) ◽  
pp. 47-57
Author(s):  
S A Kaznacheev ◽  
T S Zimenkova ◽  
A S Krasnov
Keyword(s):  
Comparative Analysis ◽  
High Speed ◽  
Permanent Magnets ◽  
Magnetic Levitation ◽  
Experimental Studies ◽  
Volume Growth ◽  
Practical Significance ◽  
Transport Systems ◽  
Cost Of Energy ◽  
Magnetic Poles

Today, one of the most urgent tasks of modern transport systems in terms of volume growth and quality improvement, freight and passenger transportation worldwide, is to increase the speed of transportation and reduce the cost of energy resources associated with these transportations. These tasks can be solved by introducing high-speed, in particular magnetic-lev- el transport systems. In this paper, we describe and compare the variants of assemblies of magnetic poles based on the Halbach massif. The relevance of the studies carried out is confirmed by the world experience in the use of permanent magnets in the field of magneto-levitation technologies in various branches of science and technology. The purpose of the research and comparative analysis of variants of assemblies of magnetic poles based on the Halbach massif is to obtain data on the possibility of using such assembly variants in levitation systems of magnetic-leav- ing transport [7], as well as visual proof that mathematical modeling does not allow to fully describe emerging phenomena In this article, we use empirical methods of investigation. The results obtained will find their application in the design of the design, which will reduce both the mass-dimensions and the energy consumption of the levitation system. The practical significance of the studies obtained lies in the possibility of applying the principles considered practically in any magnetic-levitation transport systems. Conclusion: Based on the experimental studies, data were obtained on the levitation forces and the braking forces, which make it possible to draw conclusions about the advisability of using these assembly variants.

The Chemistry of Phenol-Formaldehyde Resin Crosslinking of EPDM as Studied with Low-Molecular-Weight Models: Part II. Formation of Inert Species, Crosslink Precursors and Crosslinks

2000 ◽  
Vol 73 (4) ◽  
pp. 706-719 ◽  
Author(s):  
Martin van Duin
Keyword(s):  
Molecular Weight ◽  
Phenol Formaldehyde ◽  
Chemical Mechanism ◽  
Formaldehyde Resin ◽  
Low Molecular Weight ◽  
Model Compounds ◽  
Dynamic Vulcanization ◽  
Ethylene Propylene ◽  
Chemical Structures ◽  
End Groups

Abstract Phenol-formaldehyde resins (resols) are the preferred crosslinking agents for the dynamic vulcanization of blends of polypropylene and ethylene—propylene—diene rubber (PP/EPDM) for the production of thermoplastic vulcanizates (TPVs). The goals of this study were to elucidate in detail the chemical structures formed using low-molecular-weight model compounds and to elaborate on the chemical mechanism of resol cure of EPDM as presented in our previous study. The use of model compounds for EPDM (2-ethylidenenorbornane [ENBH] and 4-methylheptane), but also for resol (2-hydroxymethylphenol [HMP] and 2,6-di(hydroxymethyl)-p-cresol) allowed the characterization of the chemical structures formed with the aid of gas chromatography/mass spectrometry (GC/MS). In combination with derivatization of unreacted hydroxyls a large variety of species could be distinguished with the general structure of R−phenol-[-CH2−phenol-]n−R′ (n=0, 1 or 2). R and R′ can be inert end groups resulting from degradation or disproportionation, viz. —H, —CH3 or —CHO, reactive end groups, viz. —CH2OH, and products of addition to ENBH (C9H14), viz. —CH2—C9H13. When either R or R′ is —CH2—C9H13 a model crosslink precursor is formed, when both are —CH2—C9H13 a model crosslink is formed. It has been demonstrated beyond doubt that both chroman and methylene bridged species are produced. It is still unclear what parameters determine the selectivity for chroman versus methylene bridged structures (presence of activators, structure of olefin etc.). The two major model crosslink products of HMP and ENBH have also been characterized with nuclear magnetic resonance, which confirmed the chroman and methylene bridged structures and showed that the addition of the phenol predominantly occurs at the least sterically hindered C-8 of ENBH. The yield of the reaction of resol with ENBH is enhanced by temperature increase and/or the addition of SnCl2·2H2O. 4-Methylheptane does not react with HMP. This indicates that in a PP/EPDM based TPV only crosslinking of EPDM via the residual diene unsaturation occurs and that tertiary C-atoms of PP or of the ethylene—propylene rubber (EPM) chain of EPDM are not involved. The high reactivity of ENBH compared with 1-decene or hydrogenated dicyclopentadiene supports a cationic mechanism.

DEVELOPMENT OF THE SOCKET MODULE OF THE ELECTRICAL NETWORK

2021 ◽  
pp. 102-109
Author(s):  
Oleh Zemlianskyi ◽  
◽  
Oleh Miroshnyk ◽  
Tetiana Kostenko ◽  
◽  
...  
Keyword(s):  
Experimental Studies ◽  
Transmission Mechanism ◽  
Practical Significance ◽  
Electrical Network ◽  
Laboratory Research ◽  
Electrical Networks ◽  
Short Circuits ◽  
The Wire ◽  
Abrasive Cutting ◽  
Safe Working

Purpose of the work is to determine the method of emergency de-energization of the object by cutting stranded live wires without the manifestation of emergency modes of electrical networks. Methods. As research methods, a comprehensive approach is used, which includes the analysis of research on emergency de-energization, laboratory research to determine a safe way to cut stranded wires under voltage. Results. De-energizing various objects during rescue operations and firefighting is one of the important tasks that must be performed in order to create safe working conditions for rescuers themselves. It is established that one of the ways by which it is possible to cut live multicore wires without short circuits is the use of abrasive cutting discs made of rotating electrocorundum. The design of a device for trouble-free cutting of live wires, which has a rod, a cutting element, a transmission mechanism and a device for fixing the wire. In the middle of the rod is a transmission mechanism, which is used as a shaft, one end of which is connected to the motor, and the other end through a gearbox, which is fixed to the device for fixing the wire, with a cutting element. In the laboratory conducted experimental studies that showed that the cutting of wires occurs without the manifestation of dangerous factors of electric current – short circuits, sparks, electric arcs. Scientific novelty. Approaches to cutting live multicore wires with corundum disks are substantiated, which excludes the occurrence of emergency modes of electrical networks, in particular short circuits. Practical significance. The obtained results can be used to create tools for safe emergency de-energization, which creates the preconditions for improving the safety of this type of work.

Purification of water contaminated with heavy metals by example of lead as promising material based on graphene nanostructures

2020 ◽  
pp. 34-43
Author(s):  
N. R. Memetov ◽  
◽  
A. V. Gerasimova ◽  
A. E. Kucherova ◽  
◽  
...  
Keyword(s):  
Adsorption Process ◽  
Phenol Formaldehyde ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Parameter Estimates ◽  
Maximum Adsorption Capacity ◽  
Ecological Situation ◽  
Characteristic Parameters ◽  
Purification Of Water ◽  
Graphene Nanostructures

The paper evaluates the effectiveness of the use of graphene nanostructures in the purification of lead (II) ions to improve the ecological situation of water bodies. The mechanisms and characteristic parameters of the adsorption process were analyzed using empirical models of isotherms at temperatures of 298, 303, 313 and 323 K, which correspond to the following order (based on the correlation coefficient): Langmuir (0.99) > Temkin (0.97) > Dubinin – Radushkevich (0.90). The maximum adsorption capacity of the material corresponds to the range from 230 to 260 mg/g. We research the equilibrium at the level of thermodynamic parameter estimates, which indicates the spontaneity of the process, the endothermic nature and structure change of graphene modified with phenol-formaldehyde resin during the adsorption of lead (II) ions, leading to an increase in the disorder of the system.

scholarly journals Identification of Sleeper Support Conditions Using Mechanical Model Supported Data-Driven Approach

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3609
Author(s):  
Mykola Sysyn ◽  
Michal Przybylowicz ◽  
Olga Nabochenko ◽  
Lei Kou
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Dynamic Interaction ◽  
Theoretical Research ◽  
Rolling Stock ◽  
Monitoring Methods ◽  
Beam Dynamic ◽  
Track Geometry ◽  
Data Driven Approach ◽  
Support Conditions

The ballasted track superstructure is characterized by a relative quick deterioration of track geometry due to ballast settlements and the accumulation of sleeper voids. The track zones with the sleeper voids differ from the geometrical irregularities with increased dynamic loading, high vibration, and unfavorable ballast-bed and sleeper contact conditions. This causes the accelerated growth of the inhomogeneous settlements, resulting in maintenance-expensive local instabilities that influence transportation reliability and availability. The recent identification and evaluation of the sleeper support conditions using track-side and on-board monitoring methods can help planning prevention activities to avoid or delay the development of local instabilities such as ballast breakdown, white spots, subgrade defects, etc. The paper presents theoretical and experimental studies that are directed at the development of the methods for sleeper support identification. The distinctive features of the dynamic behavior in the void zone compared to the equivalent geometrical irregularity are identified by numeric simulation using a three-beam dynamic model, taking into account superstructure and rolling stock dynamic interaction. The spectral features in time domain in scalograms and scattergrams are analyzed. Additionally, the theoretical research enabled to determine the similarities and differences of the dynamic interaction from the viewpoint of track-side and on-board measurements. The method of experimental investigation is presented by multipoint track-side measurements of rail-dynamic displacements using high-speed video records and digital imaging correlation (DIC) methods. The method is used to collect the statistical information from different-extent voided zones and the corresponding reference zones without voids. The applied machine learning methods enable the exact recent void identification using the wavelet scattering feature extraction from track-side measurements. A case study of the method application for an on-board measurement shows the moderate results of the recent void identification as well as the potential ways of its improvement.

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