Effect of Graphite Filler Type on the Thermal Conductivity and Mechanical Behavior of Polysulfone-Based Composites

The goal of this study was to create a high-filled composite material based on polysulfone using various graphite materials. Composite material based on graphite-filled polysulfone was prepared using a solution method which allows the achievement of a high content of fillers up to 70 wt.%. Alongside the analysis of the morphology and structure, the thermal conductivity and mechanical properties of the composites obtained were studied. Structural analysis shows how the type of filler affects the structure of the composites with the appearance of pores in all samples which also has a noticeable effect on composites’ properties. In terms of thermal conductivity, the results show that using natural graphite as a filler gives the best results in thermal conductivity compared to artificial and expanded graphite, with the reduction of thermal conductivity while increasing temperature. Flexural tests show that using artificial graphite as a filler gives the composite material the best mechanical load transfer compared to natural or expanded graphite

Tribological, Mechanical and Thermal Properties of Fluorinated Ethylene Propylene Filled with Al-Cu-Cr Quasicrystals, Polytetrafluoroethylene, Synthetic Graphite and Carbon Black

Antifriction hybrid fluorinated ethylene propylene-based composites filled with quasicrystalline Al73Cu11Cr16 powder, polytetrafluoroethylene, synthetic graphite and carbon black were elaborated and investigated. Composite samples were formed by high-energy ball milling of initial powders mixture with subsequent consolidation by injection molding. Thermal, mechanical, and tribological properties of the obtained composites were studied. It was found that composite containing 5 wt.% of Al73Cu11Cr16 quasicrystals and 2 wt.% of nanosized polytetrafluoroethylene has 50 times better wear resistance and a 1.5 times lower coefficient of dry friction comparing with unfilled fluorinated ethylene propylene. Addition of 15 wt.% of synthetic graphite to the above mentioned composition allows to achieve an increase in thermal conductivity in 2.5 times comparing with unfilled fluorinated ethylene propylene, at that this composite kept excellent tribological properties

Tribological, Mechanical and Thermal Properties of Fluorinated Ethylene Propylene Filled with Al-Cu-Cr Quasicrystals, Polytetrafluoroethylene, Synthetic Graphite and Carbon Black

Antifriction hybrid fluorinated ethylene propylene-based composites filled with quasicrystalline Al73Cu11Cr16 powder, polytetrafluoroethylene, synthetic graphite and carbon black were elaborated and investigated. Composite samples were formed by high-energy ball milling of initial powders mixture with subsequent consolidation by injection molding. Thermal, mechanical, and tribological properties of the obtained composites were studied. It was found that composite containing 5 wt.% of Al73Cu11Cr16 quasicrystals and 2 wt.% of nanosized polytetrafluoroethylene has 50 times better wear resistance and a 1.5 times lower coefficient of dry friction comparing with unfilled fluorinated ethylene propylene. Addition of 15 wt.% of synthetic graphite to the above mentioned composition allows to achieve an increase in thermal conductivity in 2.5 times comparing with unfilled fluorinated ethylene propylene, at that this composite kept excellent tribological properties

Mechanical and Conductive Behavior of Graphite Filled Polysulfone-Based Composites

Polysulfone-based composite materials filled with artificial, natural, or thermally expanded graphite have been investigated. Composite materials with filling degrees between 30 and 70 wt.% were prepared using solution technology. High filling levels with graphite fillers allowed for the achievement of thermal conductivity of 7.35 W/m · K and electrical conductivity of 52.9 S/cm. The use of natural graphite has been found to have the greatest impact on thermal and electrical characteristics, while materials with dispersed artificial graphite exhibit the best mechanical properties. Evolution of samples’ density and porosity with the filling degree as well as the effect of these parameters on the conductive properties have been analyzed and discussed

Simple Route to Increase Electrical Conductivity and Optical Transmittance in Graphene/Silver Nanoparticles Hybrid Suspensions

Electrical and optical properties of graphene/silver nanoparticles hybrid suspensions intended for use in inkjet printing technologies were studied. Few-layered graphene particles were manufactured via a direct ultrasonic-assisted liquid-phase exfoliation route in water/surfactant system, whereas silver nanoparticles were synthetized using a polyol process. Hybrid suspensions for graphene/silver nanoparticles mixtures showed significant reduction in mean particle size while electrical conductivity remained almost intact even after thorough centrifugation. Structuring effects in mixed colloids were very pronounced as both electrical conductivity and optical transmission showed maxima at 65 wt.% graphene. Suspensions with conductivities above 300 μSm/cm, much higher than previously reported, were obtained, and resulted in the manufacturing of films with less than 10% optical absorption throughout the visible region. These samples did not demonstrate absorption peaks attributed to silver nanoparticles’ surface plasmon resonance, which is suitable for transparent electrode applications. Suspension properties at optimal composition (65 wt.% graphene) are very promising for printed electronics as well as transparent conductive coating applications. In the paper, we establish that the optimal suspension composition matches that of the film; therefore, more attention should be paid to carefully studying electrically conductive suspensions

Mechanical Properties and Chemical Resistance of New Composites for Oil Pump Impellers

In this paper, a new class of high-performance composites and a method of their production based on the carbonization of an elastomeric matrix are proposed. The use of elastomeric matrix makes it possible to manufacture products with complex shapes, while the subsequent carbonization can significantly improve their properties by changing the chemical nature of the elastomeric matrix. Such an approach can reduce the products’ machining cost, especially for composites reinforced with super hard fillers such as silicon carbide at high filling degrees. Low-temperature carbonization makes it possible to obtain composites with mechanical behavior similar to that of ceramics. In contrast to classical elastomeric materials, the nitrile butadiene rubber (NBR)-based compounds were highly filled (300 parts per hundred rubber-PHR) with different carbon fillers and silicon carbide; then cured and carbonized at low-temperature 360 °C with the carbonization cycle of 12 h. The feasibility of the production method was validated through the manufacturing of products with complex shapes—impellers for electric centrifugal pumps. It was found that the carbonized composites have good chemical resistance and low water absorption. The composites have high Shore D hardnesses (93–96), ultimate tensile strengths (62–85 MPa), Young’s moduli (17–24 GPa), and compressive strengths (155–181 MPa)

Simple Route to Increase Electrical Conductivity and Optical Transmittance in Graphene/Silver Nanoparticles Hybrid Suspensions

Electrical and optical properties of graphene/silver nanoparticles hybrid suspensions intended for use in inkjet printing technologies were studied. Few-layered graphene particles were manufactured via a direct ultrasonic-assisted liquid-phase exfoliation route in water/surfactant system, whereas silver nanoparticles were synthetized using a polyol process. Hybrid suspensions for graphene/silver nanoparticles mixtures showed significant reduction in mean particle size while electrical conductivity remained almost intact even after thorough centrifugation. Structuring effects in mixed colloids were very pronounced as both electrical conductivity and optical transmission showed maxima at 65 wt.% graphene. Suspensions with conductivities above 300 μSm/cm, much higher than previously reported, were obtained, and resulted in the manufacturing of films with less than 10% optical absorption throughout the visible region. These samples did not demonstrate absorption peaks attributed to silver nanoparticles’ surface plasmon resonance, which is suitable for transparent electrode applications. Suspension properties at optimal composition (65 wt.% graphene) are very promising for printed electronics as well as transparent conductive coating applications. In the paper, we establish that the optimal suspension composition matches that of the film; therefore, more attention should be paid to carefully studying electrically conductive suspensions

Formation of ethylene-vinyl acetate composites filled with Al–Cu–Fe and Al–Cu–Cr quasicrystallline particles

Icosahedral Al65Cu23Fe12 and decagonal Al73Cu11Cr16 quasicrystalline powders were synthesized by the mechanical alloying and subsequent annealing. Morphology evolution at mechanical alloying of Al-based powders was found to be determined by competition between cold welding and fracture mechanisms. Mechanical alloying results in formation of coarse agglomerates consisting of fine particles. The chemical binding between the polymer matrix and quasicrystals, destruction of agglomerated at extrusion, and the uniform distribution of quasicrystals over the polymer melt were provided by surface treatment of quasicrystalline particles with silanes. The highly filled (up to 60 wt%) ethylene-vinyl acetate/quasicrystals composites were obtained, and their rheological characteristics were studied. It was shown that the fluidity of the melt is retained at a high level providing uniform distribution of quasicrystalline particles over the polymer. Keywords: Quasicrystals, Ethylene-vinyl acetate, Silanes, Mechanical alloying, Extrusio

Low-Temperature Carbonized Elastomer-Based Composites Filled with Silicon Carbide

Thermally stable composites obtained by the low-temperature carbonization of an elastomeric matrix filled with hard dispersed silicon carbide particles were obtained and investigated. Evolution of the microstructure and of mechanical and thermal characteristics of composites during thermal degradation and carbonization processes in a wide range of filling from 0 to 450 parts per hundred rubber was studied. For highly filled composites, the compressive strength values were found to be more than 200 MPa; Young’s modulus was more than 15 GPa. The thermal conductivity coefficient of composites was up to 1.6 W/(m·K), and this magnitude varied slightly in the temperature range of 25–300 °C. Coupled with the high thermal stability of the composites, the observed properties make it possible to consider using such composites as strained friction units instead of reinforced polymers