scholarly journals CRYSTALLIZATION HEAT OF HIGH HEAT CONDUCTING POLYMER COMPOSITES BASED ON POLYETHYLENE FILLED WITH COPPER MICROPARTICLES

2019 ◽  
Vol 41 (2) ◽  
pp. 19-26
Author(s):  
N.M. Fialko ◽  
R.V. Dinzhos ◽  
R.V. Dinzhos ◽  
N.C Koseva
Keyword(s):  
Specific Heat ◽  
Polymer Composites ◽  
Mass Fraction ◽  
Experimental Studies ◽  
Polymer Melt ◽  
High Heat ◽  
Heat Conducting ◽  
Crystallization Heat ◽  
Conducting Polymer Composites ◽  
Cooling Velocity

The results of experimental studies of the specific heat of crystallization of polymer composites based on polyethylene filled with copper microparticles are presented. Data concerning the effects on the crystallization heat of the studied composites on such factors as the mass fraction of the filler and the cooling rate of the composites from the melt are presented. The corresponding studies were performed with a change in the mass fraction of the filler from 0.3% to 4.0% and the cooling velocity of the microcomposite from the melt from 1 K/min to 20 K/min. It is shown that the specific heat of crystallization decreases significantly with increasing speed VT and the mass fraction of the filler ω. The results of the comparison of the values of the specific heat of crystallization of polymer microcomposite, obtained by a method based on the mixing of components in a dry form and in a polymer melt, are presented. It was established that the first of the indicated methods correspond to large values of the heat of crystallization.

scholarly journals Creation of low-thermal-conductivity polymer nanocomposites for internal gas vents of boiler chimneys

2020 ◽  
pp. 57-68
Author(s):  
N. Fialko ◽  
◽  
R. Dinzhos ◽  
V. Prokopov ◽  
Ju. Sherenkovsky ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Polymer Nanocomposites ◽  
Conducting Polymer ◽  
Heat Conductivity ◽  
Young's Modulus ◽  
Structural Characteristics ◽  
Experimental Studies ◽  
Polymer Melt ◽  
Heat Conducting ◽  
Scanning Calorimetry

Methods and results of experimental studies of thermophysical, structural and mechanical properties of low-heat-conducting polymer nanocomposites, oriented to use for gas ducts and chimneys of boiler installations, as well as various other gas and water communications are presented. In this work, on the basis of the performed set of methodological studies regarding the analysis of the legitimacy of using different models of heat conductivity for predicting the heat-conducting properties of these composites, the possibility of using for this prediction a number of models of the theory of the effective medium and the theory of percolation is considered. The analysis of thermophysical properties, structural characteristics and Young's modulus of low-heat-conductivity polymer nanocomposites based on polyethylene and polypropylene is carried out. Using these nanocomposites as an example, the achievement of a significant increase in their Young's modulus in comparison with unfilled polymers with a relatively small increase in heat conductivity is demonstrated. To obtain nanocomposites, we used a method based on mixing the components in a polymer melt using an extruder and then shaping the composite into the required shape by hot pressing. The method of differential scanning calorimetry was used to determine Young's modulus. On the basis of the studies carried out, the possibility of obtaining low-heat-conducting polymer nanocomposites with improved mechanical characteristics has been shown. In particular, it was shown that for nanocomposites based on polyethylene or polypropylene filled with CNTs (carbon nanotubes) or nanodispersed aerosil particles, with a mass fraction of the latter up to 2%, the following takes place a relatively insignificant increase in heat conductivity coefficients and a significant increase in the modulus of elasticity in tension. The research data also made it possible to obtain for the developed nanocomposites the temperature dependences of their specific mass heat capacity and, on this basis, to analyze the regularities of changes in the structural characteristics of these materials.

scholarly journals Electrical Conductivity of Conducting Polymer Composites based on Conducting Polymer/Natural Cellulose

ELKHA ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 84
Author(s):  
Berlian Sitorus ◽  
Mariana B Malino
Keyword(s):  
Electrical Conductivity ◽  
Polymer Composites ◽  
Conducting Polymer ◽  
Electrochemical Impedance ◽  
Peat Soil ◽  
Experimental Studies ◽  
Hybrid Architecture ◽  
System Method ◽  
Natural Cellulose ◽  
Conducting Polymer Composites

– Merging each of the best properties of components into a composite design or hybrid architecture opens up opportunities to develop electroconductive materials as conducting polymer composite. This work deals with studying the electrical conductivity of conducting polymer composites made of cellulose extracted from two  biomass: empty fruit bunch from oil palm and peat soil. Two kinds of conducting polymers have been used to fabricate the composites, i.e. polyaniline and polypyrrole, which are polymerized from their monomers, aniline and pyrrole. The novelty of this research is the using of biomass as the source of cellulose to produced conducting polymer composites by adding conducting polymer as filler into polymer matrix. We report experimental studies about the influence of monomer addition on the electrical conductivity of composites produced. The conductivity of the material was measured by using the Electrochemical Impedance System method. The experiments were carried out as a four-set experiment, using two different cellulose sources, EFB and peat soil, combined with aniline and pyrrole. The mass ratio variations of the monomer: cellulose are 1, 2, 3, and 4. The conductivities of the composites increased when more aniline or pyrrole was blended with the extracted cellulose from each source, either EFB or peat soil. The conductivity of composite PANI/EFB, which is 3.5 ´10-3 - 1.1´10-2 S/cm, is in the semiconductor range that makes the composites useful for many applications.

scholarly journals Establishment of regularities of influence on the specific heat capacity and thermal diffusivity of polymer nanocomposites of a complex of defining parameters

2021 ◽  
Vol 6 (12 (114)) ◽  
Author(s):  
Nataliia Fialko ◽  
Roman Dinzhos ◽  
Julii Sherenkovskii ◽  
Nataliia Meranova ◽  
Sergii Aloshko ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Composite Material ◽  
Composite Materials ◽  
Thermal Diffusivity ◽  
Melting Point ◽  
Specific Heat ◽  
Polymer Nanocomposites ◽  
Specific Heat Capacity ◽  
Mass Fraction ◽  
Polymer Melt

This paper reports a series of experimental studies to establish regularities of the integrated effect exerted on the specific heat capacity of polymer nanocomposites by such factors as the temperature regime of their production, the value of the mass fraction of the filler, and the temperature of the composite material. The studies were conducted for nanocomposites based on polypropylene filled with carbon nanotubes. When obtaining composites, the method of mixing the components in the melt of the polymer was used. During the studies, the temperature of nanocomposites varied from 295 to 455 K, the mass fraction of the filler ‒ from 0.3 to 10 %. The basic parameter of the technological mode for obtaining composite materials, the value of overheating the polymer melt relative to its melting point, varied in the range of 10...75 K. It is shown that the temperature dependence of the specific heat capacity of the considered composites is sensitive to changes in the overheating of the polymer melt only in the region maximum values of the specific heat capacity. Concentration dependences of the specific heat capacity of the considered nanocomposites at different values of their temperature and the level of overheating of the polymer melt have been built. The studies have been carried out to identify the effects of the influence of the above parameters on the coefficient of thermal diffusivity of nanocomposites. It has been established, in particular, that an increase in the level of overheating the polymer could lead to a very significant increase in the coefficient of thermal diffusivity, which is all the more significant the higher the proportion of filler and the lower the temperature of the composite material. It is shown that the level of overheating the polymer melt relative to its melting point is a parameter that can be used as the basis for the creation of polymer composite materials with specified thermophysical properties.

STUDIES OF THE INFLUENCE ON THE HEAT-CONDUCTING PROPERTIES OF NANOCOMPOSITES OF THE TEMPERATURE REGIME OF THEIR PREPARATION

2017 ◽  
Author(s):  
Nataliia Fialko ◽  
◽  
Roman Dinzhos ◽  
Viktor Prokopov ◽  
Julii Sherenkovskiy ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Melting Temperature ◽  
Temperature Regime ◽  
Heat Conductivity ◽  
Experimental Studies ◽  
Polymer Melt ◽  
Heat Conducting ◽  
Heat Conductivity Coefficient

The results of experimental studies of the dependence of the heat conductivity of nanocomposites based on polypropylene filled with carbon nanotubes on the level of overheating of the polymer melt relative to its melting temperature are presented. It was found that with an increase in this level, the value of the heat conductivity coefficient of composites increases. It is shown that when a certain overheating is reached, its further growth does not provide an increase in the heat conductivity of nanocomposites. On the basis of the obtained regularity, the value of the rational level of overheating was determined.

scholarly journals NATURAL TESTS OF THE EXPERIMENTAL SAMPLE OF THE THERMOELECTRIC SYSTEM, BASED ON JOINT USE OF HIGH-CURRENT THERMOELECTRIC BATTERIES AND ALL-METAL THERMAL CONDUCTORS

2019 ◽  
Vol 45 (3) ◽  
pp. 68-75
Author(s):  
D. V. Evdulov ◽  
T. A. Ismailov ◽  
R. Sh. Kazumov ◽  
T. E. Sarkarov
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Experimental Studies ◽  
High Heat ◽  
Heat Conducting ◽  
Thermal Power Plants ◽  
Experimental Sample ◽  
High Current ◽  
Temperature Changes ◽  
Combined Use

Objectives. The aim of the article is to develop and study a thermoelectric system based on the combined use of high-current thermoelectric batteries and heat pipelines made of high-heatconducting material (e.g. copper or aluminum), to conduct full-scale experimental studies of the experimental sample of thermal power plants.Method. The design of the device of the experimental stand of the prototype on the basis of the combined use of high-current thermoelectric batteries and heat pipelines made of high-heat-conducting material is presented. The technique of full-scale tests of the prototype on a specially created laboratory bench to confirm the adequacy of the results of thermal power plants.Result. Temperature changes in different points of thermal power plants at fixed and different supply currents, temperature changes at the end of the heat pipeline in time at different supply currents of thermal power plants are investigated. The comparison of experimental and calculated data of the prototype is carried out.Conclusion. The results of experimental studies have shown the effectiveness of the developed thermoelectric system for remote separation of the cold source and the cooling object. It is shown that it is possible to increase the efficiency of thermal power plants with the combined use of high-current batteries and heat pipelines made of high-heat-conducting material.

Hazardous Gases Sensors Based on Conducting Polymer Composites: Review

2021 ◽  
pp. 138703
Author(s):  
Maamon A. Farea ◽  
Hamed Y. Mohammed ◽  
Sumedh M. Shirsat ◽  
Pasha W. sayyad ◽  
Nikesh N. Ingle ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Conducting Polymer ◽  
Hazardous Gases ◽  
Conducting Polymer Composites

Possible Mechanisms for Thermal Conductivity Enhancement in Nanofluids

2006 ◽  
Author(s):  
Amit Gupta ◽  
Xuan Wu ◽  
Ranganathan Kumar
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Brownian Motion ◽  
Brownian Dynamics ◽  
Lattice Vibration ◽  
Experimental Studies ◽  
High Heat ◽  
Conductivity Enhancement ◽  
High Heat Transfer ◽  
Dynamics Simulations

This study discusses the merits of various physical mechanisms that are responsible for enhancing the heat transfer in nanofluids. Experimental studies have cemented the claim that ‘seeding’ liquids with nanoparticles can increase the thermal conductivity of the nanofluid by up to 40% for metallic and oxide nanoparticles dispersed in a base liquid. Experiments have also shown that the rise in conductivity of the nanofluid is highly dependent on the size and concentration of the nanoparticles. On the theoretical side, traditional models like Maxwell or Hamilton-Crosser models cannot explain this unusually high heat transfer. Several mechanisms have been postulated in the literature such as Brownian motion, thermal diffusion in nanoparticles and thermal interaction of nanoparticles with the surrounding fluid, the formation of an ordered liquid layer on the surface of the nanoparticle and microconvection. This study concentrates on 3 possible mechanisms: Brownian dynamics, microconvection and lattice vibration of nanoparticles in the fluid. By considering two nanofluids, copper particles dispersed in ethylene glycol, and silica in water, it is determined that translational Brownian motion of the nanoparticles, presence of an interparticle potential and the microconvection heat transfer are mechanisms that play only a smaller role in the enhancement of thermal conductivity. On the other hand, the lattice vibrations, determined by molecular dynamics simulations show a great deal of promise in increasing the thermal conductivity by as much as 23%. In a simplistic sense, the lattice vibration can be regarded as a means to simulate the phononic transport from solid to liquid at the interface.

scholarly journals Establishing patterns in the effect of temperature regime when manufacturing nanocomposites on their heat-conducting properties

2021 ◽  
Vol 4 (5(112)) ◽  
pp. 21-26
Author(s):  
Nataliia Fialko ◽  
Roman Dinzhos ◽  
Julii Sherenkovskii ◽  
Nataliia Meranova ◽  
Diana Izvorska ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Regime ◽  
Main Parameter ◽  
Polymer Melt ◽  
Effect Of Temperature ◽  
Heat Conducting ◽  
Composite Manufacturing ◽  
Energy Saving Technology ◽  
Percolation Thresholds ◽  
The Impact

This paper reports the experimental study carried out to establish the dependence of the thermal conductivity of polypropylene-based nanocomposites filled with carbon nanotubes on the main parameter of the temperature regime of their manufacturing ‒ the level of overheating a polymer melt relative to its melting point. The study has been conducted for nanocomposites that were manufactured by applying a method based on the mixing of components in the polymer melt applying a special disk extruder. During the composite manufacturing process, the level of melt overheating varied from 10 to 75 K, with the mass share of filler ranging from 0.3 to 10.0 %. It is shown that increasing the overheating of a polymer melt causes an increase in the thermal conductivity of the composites. However, when the overheating has reached a certain value, its further growth does not increase the thermal conductivity of nanocomposites. Based on the established pattern, the rational level of this overheating has been determined. That resolves the tasks of manufacturing highly heat-conducting nanocomposites and implementing appropriate energy-saving technology. Data have been acquired on the effects of the impact of the amount of polymer melt overheating on the values of the first and second percolation thresholds for the examined nanocomposites. It is established that the value of the first percolation threshold is more sensitive to the specified amount of overheating. The dependences of the density of the examined composites on the level of polymer melt overheating have been derived. The correlation between a given dependence and the nature of a corresponding change in the thermal conductivity of the composites has been established. Applying the proposed highly heat-conducting nanocomposites is promising for micro and nanoelectronics, energy, etc.

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