Mixed Fillers Research Articles

Vapor Permeability of Thin-Film Composite Materials Based |on Polyethylene

The study of the vapor permeability and surface structure of polyethylene films modified with organic filler (casein) and mixed organic-mineral fillers stored under closed storage conditions have been shown. Changes in diffusion characteristics are shown depending on the type and amount of filler in long-term (up to 7 years) studies. It was established that the injection into the polyethylene matrix of fillers and additives significantly changes the structure formation with long-term aging. Water vapor permeability of polyethylene film modified by fillers increases along the subsequent aging. However, the deviation of characteristics at 7 years of storage does not exceed the value of WVTR = 0.6 mg·m-2·s-1, even taking into account the small thickness of the samples, which in most cases the long-term use of such a product is permissible. Electron microscopic studies of modified films have been carried out.

Study on conductive mechanism of graphene conductive and anticorrosive coatings on steel bar surface in concrete

When conductive and anticorrosive coatings are applied on the surface of reinforcing bars, electrochemical protection measures can be taken when the construction need secondary maintenance. Because graphene is a sp2 hybrid honeycomb structure, higher conductivity can be obtained by adding a small amount of graphene in the coating. In this paper, graphene-based conductive anticorrosive coatings were prepared with mixed conductive fillers (acetylene carbon black, conductive carbon black, graphite, graphene and zinc powder). The conductive mechanism was determined by studying the effects of conductive properties on the change of the content of different conductive fillers and analyzing the microstructural characteristics of conductive coatings with XRD, SEM, TEM and Raman spectroscopy tests. The results show that the conductivity of mixed fillers with different shapes in coatings is better than that of single filler in coatings when the filler content is the same. Because of the flexible structure and thin layer of graphene, the isolated fillers and conductive paths in different areas of the coatings can be connected with it and the conductive efficiency can be improved. The conductive paths are formed by the contact among conductive fillers in the coatings. Finally, the conductive mechanism model of graphene conductive and anticorrosive coatings was established.

Thermal Stability and Cyclic Sealing Performance of Glass Composite Seals

Glass matrix composites as sealing materials for solid oxide fuel cells (SOFCs) were prepared with Al2O3 and/or 8 mol % Y2O3-stabilized zirconia (8YSZ) fillers. Their thermal stability was evaluated by measuring thermal expansion coefficients (TECs) after heat-treatment in the 700~790°C range for 500 hours. With a glass composite containing ~2% closed porosity, and 10 vol% of Al2O3 and 8 YSZ fillers, the TEC change was 2% after heat-treatment at 750°C for 500 h. The TEC change of a base glass was as low as 1% after heat-treatment at 730°C for 500 h, demonstrating superior thermal stability of the base glass. Meanwhile, a glass composite containing ~10% closed porosity, and 10 vol% of Al2O3 fillers, the TEC change was as high as 8% after heat-treatment at 700°C for 500 h. The high thermal expansion of the porous glass composite containing Al2O3 filler could be understood considering the effect of porosity on the thermal expansion coefficient of porous materials. Thermal stability of the glass composite containing 10 vol% of Al2O3 and 8 YSZ fillers was further investigated with long-term cyclic sealability. The glass composite to STS444 seal assemblies was subjected to thermocycling between 450°C and 750°C, and survived over 14,000 h of 37 consecutive cycles. The leakage rates during thermal cycles were below 0.004 sccm cm−1 at seal operating temperature of 750°C. In summary, glass composites with mixed fillers of Al2O3 and 8YSZ showed superior thermal stability and cyclic sealing performance required for SOFC sealing materials. In this presentation, we will discuss the effect of the two different fillers on the thermal stability of glass matrix composites.

Mechanical and Tribological Properties of Polytetrafluoroethylene Composites with Carbon Fiber and Layered Silicate Fillers.

Mixtures of layered silicates (vermiculite and kaolinite) and carbon fibers were investigated as filler materials for polytetrafluoroethylene. The supramolecular structure and the tribological and mechanical properties of the resulting polymer composite materials were evaluated. The yield strength and compressive strength of the polymer increased by 55% and 60%, respectively, when a mixed filler was used, which was attributed to supramolecular reinforcement of the composites. In addition, the wear resistance increased by 850 times when using vermiculite/kaolinite fillers, which was due to protection of the surface by the formation of hard tribofilms.

Mixing of Injectable Fillers: A National Survey.

The mixing of hyaluronic acid or calcium hydroxylapatite fillers with normal saline, plain lidocaine, or lidocaine with epinephrine before injection is a familiar practice among dermatologists. However, the frequency of this practice and rationale behind it has not been well studied. To better elucidate the clinical practice of mixing fillers with other solutions before injecting among dermatologists. A survey was electronically distributed to members of the American Society for Dermatologic Surgery. Four hundred seventy-five dermatologists responded to the survey. Thirty-five percent of respondents mix fillers before injection. Solutions used were as follows: plain lidocaine (44%), lidocaine with epinephrine (36%), normal saline (30%), and sterile water (7%). Respondents mix filler for the following reasons: to decrease viscosity (40%), increase anesthesia (30%), decrease swelling (17%), and increase volume (13%). Despite the lack of evidence, more than one-third of dermatologists surveyed mix fillers with other solutions before injection. Plain lidocaine is most commonly used. The top reason for mixing fillers is to decrease viscosity and facilitate ease of injection. More scientific data are needed to support this practice and better understand the biophysical changes that occur when mixing fillers with other solutions.

Determination of nicotine in wild edible fungi by QuEChERS-ultra performance liquid chromatography-triple quadrupole mass spectrometry

Yunnan Province has many wild edible fungi resources, and of these, endogenous nicotine has received extensive attention in recent years. In this study, wild edible fungus was used as the research object, and the QuEChERS method was improved, including optimization of solvent extraction and purification conditions and optimization of the chromatographic behavior of nicotine under different mobile phase conditions for ultra performance liquid chromatography (UPLC). Combined with triple quadrupole mass spectrometry, a high-efficiency, rapid, and sensitive method for the determination of nicotine in wild edible fungi was established. The results showed that an ammonia:acetonitrile (6:94, v/v) mixed solution can completely extract nicotine from wild edible fungi, and the extraction solution was purified by graphitized carbon black (GCB) and N-propylethylenediamine (PSA) mixed filler. Then, a 0.1% (volume percentage) ammonia solution and acetonitrile were used as the mobile phases. The nicotine peak obtained in the positive ion multiple reaction monitoring (MRM) mode had a better peak shape and better response. The linear relationship of nicotine mass concentration with peak area in the range of 0.05-50.0 μg/L was good. The correlation coefficient (r2) was 0.9999. The limit of quantification was 0.2 μg/kg, and the limit of detection was 0.05 μg/kg. The average recovery rates at three spiked concentrations were in the range of 86.34%-96.4%, and the relative standard deviations varied from 4.44% to 6.3%. The sensitivity and recovery of this method are consistent with the rapid determination of nicotine in the edible fungus industry.

Modelling the critical concentration of mixed filler in mastic with synthetic wax

This article presents the results of tests of mastic containing mixed filler (limestone dust/hydrated lime) and Fisher-Tropsch synthetic wax. Synthetic wax content was controlled up to 3% (w/w). The ratio of filler in the bitumen was from 0.5 to 3 (w/w), with hydrated lime content of up to 30% w/w. The rheological properties of different mastic compositions were determined with a rheometer equipped with two parallel plates at 60°C using oscillating load. The primary purpose of the article was to determine the nature of mastic stiffness changes in the context of using hydrated lime and synthetic wax as the filler. Consequently, the article proposes a method for evaluation of the critical value of the filler phase in the phase of bitumen modified with synthetic wax. The proposed model of the mathematical function was used to determine the nature of mastic structuring throughout the range of the experiment. The model was also used to determine the critical concentration of the filler in the bitumen phase. It was demonstrated that below the critical filler concentration the mastic behaved in a significantly different manner from the behaviour observed above this critical concentration. When the critical concentration of the filler was exceeded, it resulted in an excessive increase of mastic stiffness, which was considered in the model.

Heat-Resistant Concrete Based on Alumina Cement from Substandard Raw Material

Results are provided for development of refractory concrete based on modified alumina cement using chemical industry waste. A quantitative ratio for mixed filler fractions, the effect of production factors on concrete strength, the dependence of its strength properties on form of filler, and solidification conditions are established. It is shown that with respect to physicomechanical and engineering properties the concretes developed is no worse than those existing in the market. With respect to all engineering properties this form of refractory product may be recommended as lining for high-temperature units.

Synergistic effects of conductive carbon nanofillers based on the ultrahigh‐molecular‐weight polyethylene with uniform and segregated structures

ABSTRACTTo discuss the synergistic effects of mixed conductive filler on nanocomposites, different structural carbon nanofiller/ultrahigh‐molecular‐weight polyethylene (UHMWPE) hybrid nanocomposites with uniform and segregated structure were prepared by using ethanol‐assisted dispersion, hydrazine reduction, and hot‐pressing methods. Scanning electron microscopy and polarized optical microscopy images of the nanocomposites fracture showed that the complete conductive channels could be formed in segregated nanocomposites prepared by powder mixing method. By contrast, the discontinuous electric path could be observed in the homogeneous nanocomposites prepared by the solution method. The test of conductivity performance demonstrated that the percolation threshold of carbon black (CB)/UHMWPE and multiwalled carbon nanotubes (MWCNTs)‐CB/UHMWPE nanocomposites with segregated structure were 0.42 and 0.18 vol %, which were lower than those of the nanocomposites with uniform structure (4.91 and 2.62%). The electrical conductivity of MWCNTs‐CB/UHMWPE nanocomposites with segregated structure reached to 3.0 × 10−2 S m−1 with the filler content of 1.5 vol %. In addition, the results of differential scanning calorimetry indicated that the crystallinity of UHMWPE decreased slightly with the addition of mixed filler. All of the study showed that the conductivity of MWCNTs‐CB/UHMWPE nanocomposites with segregated structure has better electrical conductivity than the uniform. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47317.

Code Switching and Code Mixing by The Government of Bali

Abstract—This study examines code-switching and code mixing realized in the interactional activities undertaken by govermental leaders in the Denpasar City of Bali Province, Indonesia. Typically I reveal the language types used by bilingual and multingual governments during code swithing and code mixing events as well as investigating their leading factors. The study was designed using qualitative research method. The results of this study indicate that code mixing dan code-switching undertaken by the leaders in the governmental area of Denpasar city involves 3 types of language, namely Balinese, Indonesian, and English. An element of code mixing filler occurring during interactional process of the leaders is tangible words and phrases. Leading factors to such phenomena of code mixing and code-switching are: language ability, speech topics, speech participants, speech situations, prestige; and creating regional or religious nuances.
 Keywords: Code mixing; code switching; governmental leader

Microstructure and properties of fine-grained isotropic graphite based on mixed fillers for application in molten salt breeder reactor

Fine-grained isotropic graphite (FG) derived from mixed fillers with different weight ratio of natural graphite flake (NG) and calcined coke was prepared by cold isostatic pressing method. The average diameters of NG and coke were both 10 μm. The structure and properties of FG were investigated and compared with IG-110 graphite from Toyo Tanso Co., Ltd. The structure and properties of FG changed regularly when the weight percentage of NG in filler varied from 0 to 100%. The average pore diameter and porosity respectively minimized from 1.05 to 0.183 μm and 17.1 ± 0.1% to 11.8 ± 0.1%. Nevertheless, thermal conductivity at 298 K and density respectively increased from 93 ± 2 to 130 ± 2 W/m·K and 1.74 ± 0.02 to 1.85 ± 0.02 g/cm3. Result of molten salt infiltration experiment indicated that FG exhibited much better molten salt barrier property than IG-110 once the NG in filler excess 50 wt%. Especially, only 0.085 wt% fluoride salt could be detected for the graphite derived from 100% NG even up to 10 atm, which implied it could nearly totally inhibit the molten fluoride salt permeation and NG might be used as filler to fabricate moderator or reflector graphite materials for molten salt breeder reactor.

Dielectric properties of epoxy composites with mixed fillers including graphite nanoplatelets/BaTiO3

The electrical properties of L285 epoxy composite materials (CMs) with a mixed filler including graphite nanoplatelets (GNP)/barium titanate(BT) at various GNP concentrations and at 35 wt.% of BT are measured using the AC impedance spectroscopy with frequencies ranging from 1 kHz to 2 MHz. The complex permittivity and its frequency dependence increase with the GNP content. The addition of a BT filler in GNP/L285 CM increases the percolation threshold in addition to a slight increase in the permittivity, allowing a higher GNP content in the composite without the formation of a conductive network. The AC conductivity increases and its dependence on the frequency decreases, as the GNP content increases.

EFFECTS OF MIXING PARAMETERS AND THEIR INTERACTIONS ON PROPERTIES OF CARBON BLACK FILLED STYRENE-BUTADIENE RUBBER

ABSTRACT The effects of various mixing parameters on state-of-mix and vulcanizate properties of carbon black filled styrene-butadiene rubber prepared by an intermeshing-rotor internal mixer were observed. The parameters studied include mixing time, rotor speed, fill factor, and filler loading. The interactions between these parameters are also focused. To do this, the mixing parameters are changed simultaneously, and the data are analyzed using response surface methodology. Results reveal that the dispersion index, Payne effect, and tensile properties are not linearly related to mixing time and filler loading but are linearly related to rotor speed and fill factor. The effect of mixing time on dispersion index and Payne effect depends strongly on the levels of rotor speed and filler loading. Increasing the rotor speed or filler loading reduces the effect of mixing time on dispersion index and, thus, on the Payne effect. Among the four parameters, filler loading shows the strongest effect on tensile strength (TS) and modulus at 100% elongation (M100). In addition, the effect of filler loading on the tensile properties depends mainly on the levels of mixing time and fill factor, for example, increasing of fill factor reduces the effect of filler loading on both TS and M100.

Research on pavement performance of mixed filler with alkaline residue-expansive soil

The expansive soil, a special clay, can cause crack, bulge, landslides and other accidents in the highway subgrade. To reduce the harm of expansive soil and realize the resource utilization of alkaline residue which is industrial solid waste, different ratio of alkaline residue and expansive soil with medium expansive potential are mixed as subgrade filling. A series of experiments are carried out for the pavement performance of the mixture. The results show that the swelling ratio of the mixture decreases significantly with the mixing rate. The longer the curing time is, the lower the swelling ratio will be. And the expansibility is completely eliminated in 28 days. The unconfined compressive strength(UCS) heightens with the growth of mixing rate, and when the mixing rate reaches 30%, the increasing level gradually stabilizes. Similarly, the curing time has an obvious effect on the unconfined compressive strength. After cured for 14 days, the UCS of samples is twice of that not cured. And the cohesion goes up in first stage, then decreases, and peaked as the mixing rate reaches to 30%. However, the internal friction angle changes little. The CBR increases with the increase of mixture ratio and the curing time. In addition, the mechanism of alkali residue modifying curing expansive soil is mainly based on the substitution effect of alkali residue, coagulation reaction and ion exchange of alkali residue - expansive soil.

Adsorption Characteristics of Several Bioretention-Modified Fillers for Phosphorus

To optimize the bioretention mixed fillers with better removal of phosphorus, this paper studies the adsorption characteristics of single filler and modified mixed filler through static adsorption experiments, and adopts the dynamical mini-column experiments to examine the adsorption capacities of the soil and modified mixed fillers. Results show that, in the static adsorption experiments, both water treatment residual (WTR) and fly ash exhibit good adsorption capacity when used as a single filler and modifier. Adsorption capacity increases with increasing WTR and fly ash dosage in the mixed filler. The modified mixed filler with WTR exerts a clear effect in the dynamic adsorption experiment, which is unsaturated when influent phosphorus concentration is 1 mg/L and inflow amount is equivalent to 15 years of precipitation. The adsorption capacity of WTR is 3.5–4.5 times that of other mixed fillers. Fly ash as a modifier shows a poor dynamic adsorption effect and thus must be continuously studied. In this study, WTR is recommended as a bioretention phosphorus removal additive. In engineering applications, the amount of WTR added can be controlled within 5–10% (by mass) according to influent phosphorus concentration.

Polycarbonate biocomposites reinforced with a hybrid filler system of recycled carbon fiber and biocarbon: Preparation and thermomechanical characterization

ABSTRACTIn this article, we present the investigation of the use of a partly biobased hybrid reinforcement system to improve the mechanical properties of polycarbonate (PC). To minimize the amount of recycled carbon fibers (rCFs) used in this study, their initial quantity of 20% was reduced and replaced by pyrolyzed biocarbon (BC) particles in amounts of 5%, 10%, 15%, and 20%. The materials were prepared during an extrusion‐/injection‐molding processing procedure. In addition to basic mechanical tests (tensile, flexural, and Izod tests), the samples were also subjected to detailed dynamic mechanical analysis to determine the thermomechanical relationships, such as the C factor, entanglement density, adhesion factor, and reinforcing efficiency. The results confirm the positive effect of hybridization, especially for the samples with low BC contents. In relation to the 20% pure BC composites, the hybrid samples containing the same amount of mixed filler (10%; rCF10–BC10) achieved an almost triple (270%) increase in the tensile strength and a 35% increase in the modulus. The impact resistance was also increased by 170%. Differential scanning calorimetry analysis showed significant changes in the glass‐transition temperatures for the BC‐rich samples; this was due to the sensitivity of the PC matrix to the processing degradation. The application of a small quantity of epoxy‐based chain extender proved to be effective in reducing this unfavorable phenomenon. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46449.

Modeling the effects of parameter optimization on three bioretention tanks using the HYDRUS-1D model

The operation effects of bioretention on different tanks were investigated through tests and simulations. Three layered bioretention tanks, namely, #1, #2, and #3, were selected for intermittent operation tests. The artificial filler layers of the tanks consisted of mixed fillers of fly ash and sand, blast furnace slag, and planting soil. Models were established by using HYDRUS-1D software based on test results. The sensitivity of model parameters was analyzed through Morris screening method. Results showed that return period, thickness of media layer, and solute concentration in the liquid phase were the parameters that significantly influenced the operation effects. The Nash–Sutcliffe efficiency coefficients of the models were greater than 0.85. The simulation results showed that the reduction effects at different inflow loads were better under low loads than under high loads. The comprehensive reduction rate of pollutant load was 5.22% less under high concentrations than under low concentrations. The comprehensive reduction rates of water and pollutant loads were 35.97% and 20.68% greater, correspondingly, in the 1 year return period than in the 10 year return period. The artificial fillers comprising a mixture of fly ash and sand also showed the optimal reduction effects, with comprehensive reduction rates of 69.33% and 83.08% for water and pollutant load, respectively. The reduction effects of water and pollutants for the #1 tank presented an upward trend, whereas those for the #2 tank showed a downward trend given an increase in planting soil thickness. An increase in media thickness enhanced the reduction effects. The media with 60 cm thickness demonstrated the optimal effect.

Self-Assembly of Carbon Nanotubes and Boron Nitride via Electrostatic Interaction for Epoxy Composites of High Thermal Conductivity and Electrical Resistivity

The self-assembled oxidized carbon nanotubes (oCNTs) with the silane functionalized hexagonal boron nitrides (oCNTs@fBN) via electrostatic interaction were used to improve the thermal conductivity while maintaining the electrical insulation properties of the epoxy composites. The oCNTs were separately immobilized on the edges of hexagonal boron nitride (hBN), which prevent oCNTs from continuously contacting with each other. The thermal conductivity and volume resistivity of oCNTs@fBN filler loaded epoxy composites were measured and compared with the epoxy composites with a filler of hBN, a mixed filler of oCNTs, and silane functionalized hBN (fBN). The thermal conductivity of the epoxy composites containing 20 wt% of oCNTs@fBN10 was 1.26 W·m-1·K-1, which is higher than 600% compared to that of neat epoxy and the volume resistivity of the epoxy composites was in an insulation region even at high content of oCNTs@fBN filler. The significant improvement in thermal conductivity was attributed to the formation of linkages between oCNTs and fBN and the good compatibility of oCNTs@fBN in the epoxy matrix.

Anisotropic thermally conductive flexible polymer composites filled with hexagonal born nitride (h-BN) platelets and ammine carbon nanotubes (CNT-NH2): Effects of the filler distribution and orientation

High thermal conductive filler (hexagonal boron nitride and carbon nanotube) reinforced polymer composites have obtained a growing attention in the microelectronic industry for their good thermal conductivity but electrical insulating. In this work, a synergistic hybrid structure of two fillers with different dimensions had been designed and prepared by taking hexagonal born nitride (h-BN) platelets and ammine carbon nanotubes (CNT-NH2) into the flexible polymer matrix. Using cycloaliphatic epoxy resin (CER) as the polymer matrix, a serious of (a) h-BN/CER based, (b) hybrid filler h-BN@CNT-NH2/CER based, and (c) mixed filler CNT-NH2 and h-BN/CER based composites were prepared. In this structure, h-BN (and h-BN@CNT-NH2) platelets stacked along the horizontal direction under the assistance of gravity force and interactivity between the fillers. The orientation of the h-BN platelets was investigated by scanning electron microscope (SEM) of the cracked cross-section of the composite film and XRD measurement via calculating the orientation function (f). The CNT-NH2 was embedded within the network to improve the filler-filler contact or network-density. Due to the anisotropic properties of h-BN platelets and dispersion states of CNT-NH2, the composites with different structures presented different and special properties, including thermal/electrical conductivity properties, mechanical properties, and thermal decomposition properties. The analysis of structure and mechanism of thermal decomposition were then proposed to explain those interesting properties. The incorporation and dispersion states of CNT-NH2 in the composites played an important effect on the enhancement of the thermal conductivity properties both included in-plane (∼1.76 W/m·K) and through-plane (∼1.09 W/m·K) thermal conductivity. Additionally, the good electrical insulating properties and mechanical properties of the composites provided a potential application in the thermal management areas. The solvent-free procedure was environment friendly, easy operation, and suitable for the practical application in large scale.

TLP repaired IN738LC superalloy with uneven surface defect gap width after post heat treatment: Microstructure and mechanical properties

Cracks repairing of superalloy is very important to the aerospace industry. Most of the crack repairing studies have the same “crack width” which is quite different from the taper-shaped crack in reality. In this study tapered slots with maximum 200 μm width were artificially made by femtosecond laser in small plates of IN738LC superalloy to imitate service cracks. The “cracks” were repaired by diffusion brazing with a mixed filler alloy at 1100 °C for 24 h and followed by homogenization at temperatures of 1160 °C (HT-1), 1180 °C (HT-2) and 1190 °C (HT-3). With increasing homogenization temperature and time, the volume faction of borides in diffusion affected zone (DAZ) decreased. During the homogenization with HT-3, most of the borides in the DAZ of the joint dissolved, merely a small quantity of others coarsened by Ostwald ripening. In order of the processes as-bonded, HT-1, HT-2 and HT-3, the chemical composition of the isothermal solidification zones (ISZs) gradually came close to that of the base metal and the hardness of the ISZs increased, while the hardness of the DAZs decreased. A uniform bonded joint could be obtained with HT-3, and the shear strength of the joint reached up to approximately 95% of the base metal. The corresponding fracture path and fractography of the samples were observed to explain the mechanism of strength evolution.