Increasing Filler Content Research Articles

Mechanical and Tribological Performance of Polypropylene/Tin Powder Composites

In this study, the effect of Tin powder filler content on the mechanical and tribological performance of Tin filled Polypropylene (PP) composites were investigated. Polypropylene composites were prepared in a Brabender kneading chamber. The melt was transferred to a laboratory hot press and compression molded into samples for tests. The mechanical performances of the polymer based composites were determined by tensile and notched izod impact tests. The tribological tests were carried out in dry condition using pin-on-disc at 0.5−1.5 m/s Sliding Speed (SS) and 10–30 N loads. The mechanical test results demonstrated that the incorporation of Tin powders increased the Tensile Strength (TS) (5.6%), tensile modulus (TM) (19.8%) and izod Impact Strength (IS) (41.8%) while decreased the Elongation at Break (EB) (80%) values of Tin powder filled PP composites. The Friction Coefficient (COF) and Specific Wear Rate (SWR) decreased with the increase in filler content. The COF of unfilled PP, PP-8% Tin powder, PP-16% Tin powder and PP-24% Tin powder composites decreased about 20%, 23.4%, 21.8% and 29.3% with the increase in applied load from 10 N to 30 N, respectively. The SWR of the Tin powder filled PP composites decreased by 91% compared to unfilled PP polymer at 1.5 m/s speed and 30 N load value.

Investigation of Electrical and Thermal Properties of Epoxy Resin/Silicon Carbide Whisker Composites for Electronic Packaging Materials

This article explores the potential of epoxy resin/silicon carbide whisker (EP/SiCw) composites (1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%) as the field-dependent conductivity (FDC) packaging materials for the high-voltage power modules by investigating their thermal and electrical properties at different temperatures. The cross-sectional morphology of the prepared materials is characterized by field emission-scanning electron microscopy (FE-SEM). The thermal analysis consists of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The electrical properties, such as dc conductivity, dielectric spectroscopy, thermally stimulated discharge current (TSDC), space charge distribution, and dc breakdown strength, are measured. The molecular orbital energy levels of the EP and SiCw monomers are calculated by quantum chemical calculation (QCC) to analyze the effect of EP interfacial trap sites on the electrical properties. The effect of the EP/SiCw interfacial charges and electrical field distortion on the electrical properties of the EP/SiCw composites with different filler content is investigated by the finite-element method (FEM) simulation. It is found that the 2 wt% EP/SiCw composite has a better thermal performance. The 1 wt% has lower real permittivity, lower trap density, lower space charge accumulation, and higher breakdown strength. The EP/SiCw composites have a higher trap level than the pure EP. The nonlinearity percolation threshold of the EP/SiCw composites is 3 wt%. As the filler content increases, the nonlinear conductivity coefficient of the EP/SiCw composites becomes higher, whereas the breakdown strength decreases due to the electric field distortion near the electrodes caused by the apparent hetero charge accumulation at high filler content.

Mechanical, Dynamic-Mechanical, Thermal and Decomposition Behavior of 3D-Printed PLA Reinforced with CaCO3 Fillers from Natural Resources.

This study evaluates the effect of CaCO3 fillers extracted from waste eggshells on 3D-printed PLA performance. Samples of neat PLA and PLA reinforced with CaCO3 fillers embedded with different wt.% were prepared using an FDM (fused deposition modeling) technology. The samples were examined using mechanical, dynamic mechanical, thermal, and thermal decomposition analyses. The results revealed increasing elastic moduli, tensile strength, and flexure as the filler content increased. The rheological results from the MFR tests showed that the filler content did not influence the PLA-based samples’ processability. Further, the thermal degradation of neat and various CaCO3-wt.%-reinforced PLA specimens revealed relatively small discrepancies in their exposure to the temperature increase, mainly concerning the eggshell organic components and volatile components, from their processability up to 300 °C. By contrast, the increased filler content positively shifted the peaks along the temperature scale at the maximum degradation rate. Additionally, the weight content of the natural reinforcement strongly influenced the surface wettability and appearance of the samples. Further, the SEM analysis featured both the presence of interlayer disturbances and the interfacial compatibility the PLA with the selected fillers.

High-performance capacitive pressure sensors Fabricated by introducing dielectric filler and conductive filler into a porous dielectric layer through a Biomimic strategy

Capacitive sensors have vast application prospects. Their dielectric layer is hardened under high pressure, the sensitivity is reduced and sensing behavior is nonlinear. To tackle this, a novel strategy is used to incorporate voids, dielectric filler and conductive filler into the dielectric layer. Firstly, “root” like dendritic colloid polyurethane (DCPU) is prepared to grasp different content of carbon nanotube (CNT) and barium titanate (BaTiO3, BT), before such hybrid filler is coated onto the backbone of PU foam. For capacitive pressure sensors, it is observed that sensitivity increases with increasing filler content. More importantly, the addition of CNT into the inner layer of hybrid filler containing BT in the outer layer leads to linear pressure sensing behavior in a wide pressure range. Furthermore, the overall performance achieves a sensitivity of 2.51 kPa−1 under 0–100 kPa and a linearity of R2 = 0.9989, and stable signals after 1000 cycles. Finally, it is successfully demonstrated that petals with a weight of 96 mg and the physiological signals of the human body such as heartbeat, swing arm amplitude, and joint bending can be detected. This work provides a new design inspiration for capacitive sensors with high sensitivity and high linearity in realizing medical health monitoring and motion detection.

PRODUCTION OF BIODEGRADABLE POLYMERIC PACKAGING MATERIALS BASED ON POLYOLEFINS AND WOOD FLOUR

The paper presents the results of a comparative study of the physics and mechanical, rheological and biodegradation characteristics of composite materials based on a mixture of polyethylenes of low (LDPE 273-83) and high (HDPE 15303-003) pressure in a ratio of 1 : 1. The composite was also filled with finely ground wood flour with a particle size of less than 200 microns (5-30% by weight) and 10% compatibilizer (functionalized by the alkaline alcoholysis splitting method of sevilene (EVA 12206-007) and a processing additive of 1% polyethylene glycol (PEG-115 (4000). It has been found that with an increase in the content of wood flour (up to 20%), the modulus of elasticity and ultimate strength practically have not changed. The tensile elongation of the composite exceeds 100% (if the content of wood flour is up to 15% by weight). The complex viscosity and shear modulus of the considered melts with different filler contents are practically at the same level. At the same time, the introduction of wood flour up to 30% and a compatibilizer (10%) promotes a slight increase in the viscosity and elasticity of melts, which practically does not affect the change in the manufacturability of the compositions in comparison with LDPE 273-83. For a comparative assessment of the ability of composites to biodegradation, moisture absorption, chemical oxygen consumption, and weight loss of composites in laboratory soil during exposure for 12 months were studied. It has been shown that as the filler content increases, the biodegradability of composites increases.

Fly Ash Epoxy Composites with Superior Fire Retardant Properties

Epoxy was loaded with varying concentrations of fly ash and was characterized for its structural properties using XRD and SEM. The XRD results revealed reduction of crystallinity with increase in filler content indicating that the composites are semi crystalline in nature. The SEM images showed that at lower concentration of filler content, fly ash is uniformly distributed within the epoxy and at higher concentrations of fly ash, agglomerates were observed. Mechanical properties such as tensile and compressive properties were estimated and the results showed that, the composites exhibit enhanced tensile strength and compressive strength for epoxy with 20 wt% fly ash. Flammable properties such as heat release rate, peak heat release rate, time to ignition, CO and CO2 yields are estimated and reported. Decrease in combustion time, peak heat release rate, time to ignition, CO and CO2 yields with increase in filler content clearly indicates the superior flammability performance of epoxy composites loaded with fly ash.

Influence of (0.19HfO2-0.81ZrO2) ceramics filler content on structural and dielectric properties of PVDF polymer

The rapid evolution of modern technology for the sustainable development of human beings demands eco-friendly, flexible, cost-effective, and lightweight smart materials. Ceramics-polymer composites are those novel materials with improved features, which fulfill the prerequisite conditions for application in flexible devices. Pristine PVDF is one of such electroactive flexible polymers which exhibits good dielectric, ferroelectric and piezoelectric properties. But, its functional properties in the perspective of device application still need improvement and this can be achieved by adding filler to the pure PVDF. In this communication, we have reported the influence of Hafnia-Zirconia (HZ) ceramics (0.19HfO2-0.81ZrO2) filler on structural, microstructural, dielectric, and electrical properties of pure PVDF matrix. The polymer-ceramics flexible composites are synthesized by an eco-friendly and cost-effective method i.e., solution casting method. The phase formation of flexible composites is confirmed from the room temperature XRD spectra. The degree of crystallinity increases with an increase in filler content. The degree of β-phase crystallinity is found to be maximum for 5 wt% of the ceramics filler. An enhanced dielectric constant of ~53 and 20 was observed (as expected) for 5 and 10 wt% of HZ ceramics filler respectively at 100 Hz due to the enrichment of polar β-phase for these two ceramics-polymer composites. The influence of filler content on the dielectric properties was explained based on the percolation model. Relaxation and conduction mechanisms of flexible composites are analyzed from the impedance spectroscopy and ac conductivity study, respectively.

Effect of Fine Aggregate Gradation on Macro and Micro Properties of Cold Recycling Mixture Using Emulsified Asphalt

In order to explore the influence of fine aggregate on the macro and micro properties of cold recycling mixture using emulsified asphalt (CRME), mechanical and microscopic property tests were carried out. The indirect tensile strength (ITS), unconfined compressive strength (UCS) and triaxial shear strength of different fine aggregate gradation was measured for analyzing the effects of fine aggregate on the mechanical strength, triaxial shear resistance and fracture energy of CRME. Meanwhile, the surface morphologies and air voids distribution of different CRME were observed by scanning electron microscopy (SEM) and X-ray computed tomography (X-ray CT). The results show that fine aggregate has a significant effect on the mechanical strength and shear resistance of CRME. With the same water and asphalt content, the fracture energy and failure strain of the mixture with less fine aggregate (G3-2) decreased by 16.2% and 18.2%, respectively. The less content of powder there was, the fewer cement hydration products there were due to some cement being coated by emulsified asphalt and the “cement hydration products fiber” length being shorter. Approximately 70% of the AFt hydration products in the G3-2 mixture were in the range of 1–4 μm, while those in the G1 mixture were in the range of 4–8 μm. With the increase in filler content, the number of air voids in the volume range of 0.5 mm3 ≤ V < 5 mm3 in CRME decreased, and the number of air voids in the volume range of V < 0.5 mm3 significantly increased, while the equivalent radius of air voids decreased slightly with the increase in filler content.

Development of natural fiber reinforced polymer composites with enhanced mechanical and thermal properties for automotive industry application

AbstractIn this research, a newly explored natural fiber named sea purslane fiber (SP) was applied as a reinforcing material with widely used thermosetting polymer epoxy polymer. Chemical treatments on the fibers were done with NaOH followed by acrylic acid treatment. Reinforcing acrylic acid treated and untreated SP fibers at variable weight percentages of fiber loading, variety of composite samples (0, 5, 10, 15, 20, and 25 wt%) were developed. The mechanical characteristics of the composites were found to improve initially with increasing filler content until reaching the optimum (20 wt%) fiber loading, after which they began to fall. At 20 wt% filler loading various properties like physical & chemical (density, water absorption, X‐ray diffraction), mechanical (tensile, flexural, impact, micro‐hardness) and thermal (thermogravimetric analysis) properties were examined and compared with untreated fiber reinforced composites. It was noticed that the treated fiber composites reveal better result as compared with untreated fibers composites. The findings provide manufacturers and engineers with a broad concept of how to use this composite to reduce weight, particularly in automotive applications.

Erosion wear characteristics of step-wise layered polymer composite materials by silica sand particles

Polymer composite materials (PCMs) can sustain themselves in harsh environments without suffering any loss of properties of the constituents. The present study focussed on erosion wear behavior of step-wise layered polymer composite materials (LPCMs). Samples were fabricated with epoxy as matrix and aluminum as filler particles using hand lay-up technique. Volume fraction of the filler was varied at four different layers along the direction thickness. Experiments were conducted at room temperature using angular shaped silica sand erodent impacting at 151 m/s and at impingement angles of 30°, 45°, 60° and 90°. Due to the variation in filler content, testing of samples was performed at two different orientations: i) top to bottom (T-B) and ii) bottom to top (B-T). The increased filler content reduced the erosion wear as tested from B-T, while a reverse trend was observed along T-B. Moreover, erosion wear was found to be higher at 45° impingement angle indicating the semi-ductile nature of LPCMs. At this angle, the erosion wear rate at top layer was 76.47% lower compared to bottom due to the presence of high filler content.

Assessing the Effect of Fe3O4 Nanoparticles on the Thermomechanical Performance of Different Forms of Carbon Allotropes/Epoxy Hybrid Nanocomposites

The incorporation of ceramic nanoinclusions in carbon nanocomposites can induce additional functionality in the field of magnetic properties, piezoelectricity, etc. In this study, series of nanocomposites, consisting of different carbon nanoinclusions (carbon black, MWCNTs, graphene nanoplatelets, nanodiamonds) and magnetite nanoparticles incorporated into a commercially available epoxy resin were developed varying the filler type and concentration. Experimental data from the static tensile tests and dynamic mechanical analysis (DMA) demonstrated that the elastic tensile modulus and storage modulus of hybrid nanocomposites increase with an increase in filler content up to almost 100% due to the inherent filler properties and the strong interactions at the interface between the epoxy matrix and the nanoinclusions. Strong interactions are implied by the increasing values of the glass transition temperature recorded by differential scanning calorimetry (DSC). On the contrary, tensile strength and fracture strain of the nanocomposites were found to decrease with filler content. The results highlight the potentials and capabilities of developing hybrid multifunctional nanocomposites with enriched properties while holding their structural integrity.

Effect of TiO2 as Filler in NaCl: Possible Applications in Ionic Storage Systems

High dielectric capacitors are increasingly used for energy storage in sustainable nanotechnologies. Here, we observed large enhancement of dielectric constant by 3 order at frequency 1kHz with moderate loss when TiO2 is added as a filler in NaCl bulk matrix. The TiO2 nanoparticles are synthesized via sol gel process and is subsequently added in varying weight percentage x in the ionic matrix of NaCl, which is represented as TiO2(x)NaCl. The parameters like dielectric constant, dissipation Loss and ac conductivity are measured with varying fraction of TiO2 in frequency range less than 25 KHz. The steady increase of dielectric constant with increasing filler content at low frequency indicates percolation type behavior which accounts for the first dielectric peak at x= 50. The dielectric loss is found to be around 1 for x< 45 whereas it tends to increases with higher filler fraction. Moreover, the frequency dependent polarization in this composite system also accounts for hopping type behavior of mobile charge carriers contributed by TiO2 as confirmed from ac conductivity measurement. Further, the samples are characterized by X-ray diffraction and Field emission scanning electron microscopy in order to study the structure and morphology of the samples. Overall, TiO2 incorporation strongly improves the dielectric behavior of the ionic matrix at low frequency, making it suitable for super dielectric material (SDM).

A self-healing and flexible Ag@carbon fiber/polyurethane composite based on disulfide bonds and application in electromagnetic interference shielding

With the wide application of electronic equipment, the demand for the efficient performance of electromagnetic interference (EMI) shielding materials has become increasingly urgent to meet different requirements and electromagnetic environments. In this study, a flexible composite with both self-healing and reliable EMI shielding functions was facilely developed. Firstly, we synthesize Ag@Carbon fiber (CF) by electroless plating method, and we can see that the silver layer wrapped CF completely by scanning electron microscope (SEM). Then we synthesize polyurethane (PU) with disulfide, and mix Ag@CF with PU mechanically to prepare Ag@CF/PU composite. Ag@CF/PU achieved satisfactory mechanical properties, EMI shielding performance and self-healing performance. When the filler content was 3 wt%, the tensile strength of composite was 1.63 MPa, the highest EMI shielding effectiveness (SE) was 10.3 dB at X-band, and self-healing efficiency of tensile strength was 96%. With the increase of filler content, the tensile strength and EMI SE of composite improved, and self-healing efficiency decrease. When the filler content was 20 wt%, the tensile strength was 7.95 MPa, the highest EMI SE was 26 dB and self-healing efficiency of tensile strength was 28%. This work demonstrated a self-healing flexible EMI shielding composite material that ensured reliability.

Cellulose nanofibril/mineral composites induced by H-bond/ionic coordination in co-refining system

Mineral fillers hinder cellulosic fiber bonding and thus limit the increase of filler content in paper. Herein, precipitated calcium carbonate (PCC)/cellulose nanofibrils (CNF) composites were fabricated by a facile and efficient strategy, i.e., co-refining process (CRP). During this process, CNF and PCC were activated by mechanochemical effect and formed encapsulation structure by calcium ion coordination and hydrogen bonding. The encapsulation structure and H-bond/ionic coordination interactions not only endowed the composite with excellent size stability but also enhanced interfacial interaction between composite fillers and cellulosic fibers. Compare with the paper filled with only PCC, PCC + CNF mixture, the tensile index of the cellulosic paper containing PCC/CNF composite was increased by 44.48% and 12.14%, respectively. These results not only provide a facile and scalable approach to increase interaction between cellulosic fiber and mineral filler but also create more possibilities for special paper-based materials with requiring high content of inorganic materials.

High-Energy Photon Attenuation Properties of Lead-Free and Self-Healing Poly (Vinyl Alcohol) (PVA) Hydrogels: Numerical Determination and Simulation.

This work numerically determined high-energy photon shielding properties of self-healing poly(vinyl alcohol) (PVA) hydrogels containing lead-free, heavy-metal compounds, namely, bismuth oxide (Bi2O3), tungsten oxide (WO3), and barium sulfate (BaSO4), through XCOM software packages. In order to understand the dependencies of the shielding properties of the hydrogels on filler contents and photon energies, the filler contents added to the hydrogels were varied from 0–40 wt.% and the photon energies were varied from 0.001–5 MeV. The results, which were verified for their reliability and correctness with those obtained from PHITS (Particle and Heavy Ion Transport code System), indicated that overall shielding performances, which included the mass attenuation coefficients (µm), the linear attenuation coefficient (µ), the half-value layer (HVL), and the lead equivalence (Pbeq), of the hydrogels improved with increasing filler contents but generally decreased with increasing photon energies. Among the three compounds investigated in this work, Bi2O3/PVA hydrogels exhibited the highest photon attenuation capabilities, determined at the same filler content and photon energy, mainly due to its highest atomic number of Bi and the highest density of Bi2O3 in comparison with other elements and compounds. Furthermore, due to possible reduction in self-healing and mechanical properties of the hydrogels with excessive filler contents, the least content of fillers providing a 10-mm sample with the required Pbeq value of 0.5 mmPb was investigated. The determination revealed that only the hydrogel containing at least 36 wt.% of Bi2O3 exhibited the Pbeq values greater than 0.5 mmPb for all photon energies of 0.05, 0.08, and 0.1 MeV (common X-ray energies in general nuclear facilities). The overall outcomes of the work promisingly implied the potential of PVA hydrogels to be used as novel and potent X-ray and gamma shielding materials with the additional self-healing and nonlead properties.

Influence of Fish Scale-Based Hydroxyapatite on Forcespun Polycaprolactone Fiber Scaffolds.

Marine waste byproducts, especially fish scales, have proved to be one of the most prominent sources for developing sustainable materials for various applications including biomedical applications. Hydroxyapatite (HAp), being one of such biomaterials that can be synthesized from the massive fish-based waste, has received plentitude of attention due to its excellent ability to promote cell growth and proliferation. However, understanding the influence of HAp on polymer matrices that are tailored for biomedical applications is still a challenge. This study is intended to develop a sophisticated yet inexpensive method to obtain nonwoven polycaprolactone (PCL) nanofibrous scaffolds and analyze the influence of calcium-deficient nanoporous hydroxyapatite (n-HAp) on the thermal, mechanical, and biological properties of these scaffolds. The n-HAp is synthesized using two different types of fish scales, carpa (CA) and pink perch (PP), by calcination followed by nanomilling. The synthesized n-HAp powder is characterized by using X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. The PCL fibrous scaffolds were developed using a novel forcespinning technique with n-HAp as the filler. The morphology of the scaffolds was characterized using SEM and Raman spectroscopy. SEM and TEM results have confirmed the size reduction of the HAp powder after nanomilling. Thermal properties were analyzed using thermogravimetric analysis and differential scanning calorimetry. The major degradation temperature has increased by 3° and was observed to be 398° for 1 wt % filler loading for both carpa and pink perch-derived n-HAp. The increase in filler content has increased the residue left after decomposition and is 4% for 5 wt % filler loading. The crystallinity percent has increased by 7% compared to neat fibers for 1 wt % filler loading. Mechanical properties were tested using tensile tests. The tensile test strength has shown 32% improvement for 1 wt % compared to neat fibers. Cell viability tests were performed using hFOB cells which have shown significant cell growth for a high filler loading of 5 wt %. The results suggest that both CA-n-HAP and PP-n-Hap-incorporated fibrous scaffolds can be used potentially for biomedical applications after careful investigation of the scaffold behavior with longer incubation periods.

Filler Influence on H2 Permeation Properties in Sulfur-CrossLinked Ethylene Propylene Diene Monomer Polymers Blended with Different Concentrations of Carbon Black and Silica Fillers.

Filler effects on H2 permeation properties in sulfur-crosslinked ethylene propylene diene monomer (EPDM) polymers blended with two kinds of carbon black (CB) and silica fillers at different contents of 20 phr–60 phr are investigated by employing volumetric analysis in the pressure exposure range of 1.2 MPa~9.0 MPa. A linear relationship is observed between the sorbed amount and pressure for H2 gas, which is indicative of Henry’s law behavior. The hydrogen solubility of EPDM composites increases linearly with increasing filler content. The magnitude of hydrogen solubility for the filled EPDM composites is dependent on the filler type. The hydrogen solubility is divided into two contributions: hydrogen absorption in the EPDM polymer and hydrogen adsorption at the filler surface. Neat EPDM reveals pressure-dependent bulk diffusion behavior. However, with increasing filler content, the diffusivity for the filled EPDM composites is found to be independent of pressure. The magnitude of filler effects on the hydrogen permeation parameter is measured in the order of high abrasion furnace CB~semireinforcing furnace CB ˃ silica, whose effect is related to the specific surface area of CB particles and interfacial structure. The correlation between the permeation parameters and filler content (or crosslink density) is discussed.

Increasing thermal stability of the roads in cryolithic zone

Automobile roads in cryolithic zone in disctinctly continental climate conditions are subject to significantly greater adverse thermal impacts, such as high diurnal temperature variations, than similar structures in milder climates. This requires higher expenses on exploitation and maintenance of the automobile roads. It is possible to mitigate these negative impacts of rapid temperature changes, reducing maintenance costs and improving safety of road use, through application of thermal protection.This contribution explores protection of road structures using materials with high thermal stability indicator within the constructive layer of the road and aims to provide tools to quickly assess the optimal concentrations of thermal accumulation filler in the thermal protection layer. Using the unconditional optimization method on the temperature conductivity coefficient of the binary mixture, simple engineering formulas were obtained to find the optimal concentration of the thermal accumulation filler. It was established that regardless of the thickness of the thermal protection layer, the optimal concentration of the filler is a constant. However, there are values outside of the optimal range beyond which the increase of filler concentration is ineffective. It was discovered that even a minimum concentration of the filler (10%) improves the thermal stability indicator twice, and at the optimal concentration of 44% there is a threefold increase in thermal stability. The formulas and their results are visually presented in the form of charts, allowing to grasp the range in optimum concentrations of thermal accumulation fillers to achieve the highest thermal stability effects.

Physical and mechanical properties of epoxy/Kota stone dust/fly ash hybrid composites for light duty structural applications

AbstractKota stone dust (KSD) and fly ash (FA) are the wastes generated from the construction industry and thermal power plant, respectively. In the present work, a novel hybrid composite is developed to utilize KSD and FA as reinforcing phases in the epoxy matrix. The hand lay‐up method is adopted for the fabrication of 12 sets of samples. Four sets are prepared with single filler KSD and eight samples are prepared with a hybrid combination of KSD and FA. The prepared samples are undergone physical and mechanical tests. To understand the compatibility between filler‐matrix and visualize the dispersion of fillers in epoxy, micrographs are taken using the scanning electron microscope. The density and void contents of the material increases with an increase in filler content. The maximum water absorption measured is 0.96% for the combination of epoxy with 40 wt% KSD and 10 wt% FA. From mechanical testing, maximum tensile strength and flexural strength obtained is 34.4 MPa and 65.4 MPa, respectively, for a combination of epoxy with 20 wt% KSD and 5 wt% FA. Compressive strength and hardness increase with either of the content of the filler and reaches 116.28 MPa and 104 Shore D number, respectively, with 40 wt% KSD and 10 wt% FA. From experimentation, it was found that mechanical properties of the hybrid composites are better as compared to that of single filler composites though physical properties are slightly compromised by hybridization of fillers.

In English

The participation of the electronic subsystem of graphene nanoparticles in heat transfer on the interfaphase surface with epoxy polymer, its participation in the thermodestruction processes of epoxy matrix and the concentration interval of the subsystem's influence on the thermal destruction of the polymer matrix are investigated. For such purpose, epoxy resin composites with oxidized and non-oxidized graphene nanoparticles have been used.The particles were obtained by electrochemical method and those are characterized by the same dispersion and analogical of defect spectra. The particles have the same crystal structure, however in composites with oxidized graphene, the participation of the electronic subsystem in thermophysical processes on the interfacial surface is blocked by the atomic layer of adsorbed oxygen. Сomposites of epoxy resin filled with the same particles of nonoxidized and oxidized nanoparticles in the filler content 0.0, 1.0, 2.0, and 5.0 wt%. The multilayered graphene particles were studied by X-ray diffraction analysis (XRD) and Raman spectroscopy (RS) methods. It was shown that the graphene particles are the 2D dimensional structures with about of 100 layers. Desorption curves of epoxy and its composites have been obtained using a programmable thermal desorption mass-spectroscopic (TDMS) technique for fragments with 15≤ m/z ≤108 and temperature interval 35 - 800 оС. The activation energy of desorption was determined from the Wigner-Polanyi equation as 35 - 150 kJ/mol, temperature and mass dependences of the quantity of desorbed atomic fragments have been calculated. It were established the graphene electron subsystem takes part in polymer structure thermodestruction for epoxy composites with nonoxidized graphene enhancing their heat resistance at graphene content С ≤ 1 wt%. With increasing filler content, the thermodestruction behavior in pristine epoxy and its composites with nonoxidized and oxidized graphene is analogical. The thermodestruction characterizes by the stepwise variations in the desorption intensity of atomic fragments. The electron subsystem of graphene particles does not participate in the heat resistance variations.