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The unsaturated zinc carboxylate/Ethylene-Propylene-Diene Monomer (EPDM) composites were prepared by mechanical blending. The effects of hydroxy (2-methylprop-2-enoato-O)zinc (ZMMA) and zinc dimethacrylate (ZDMA) on the hydrophobicity, mechanical properties, ageing resistance, and electrical properties of the composites were studied. The results show that the mechanical properties, crosslinking rate, crosslinking density, and oil resistance of the composite are significantly improved with the increase of ZMMA and ZDMA content. The crosslinking density of EPDM filled with 15 phr of ZDMA composite material is 3.22 × 10−3 mol/cm3, compared with the samples without ZDMA filling, the improvement was 175.2%, and the tensile strength reaches 16.9 MPa, which increases by 33.6%. The addition of a small amount of unsaturated carboxylate has a positive effect on the electrical properties of EPDM matrix composites. The volume resistivity of the EPDM filled with 5 phr of ZDMA is 16.2 × 1013 Ω·m, an increase of 36.1%. [ABSTRACT FROM AUTHOR]

Insulation of self-supporting insulated wire (SIW-4) is the object of the study, and the subject of the study is a mathematical model of the dependence of the specific volume electrical resistance of the SIW-4 insulation on the factors affecting its reliability. The resulting mathematical model will allow us to proceed to the development of a method for predictive assessment of the residual life of the insulation material of the conductor under study. At the first stage of the work, the influence of external factors on the electrical parameters of the SIW-4 insulation material has been studied. When forming the goal of the study, namely, obtaining a mathematical model of the dependence of the specific volume resistance of the wire insulation on the influence of external factors, difficult operating conditions have been taken into account. SIW-4 is intended for use outside buildings, i. e. it is exposed to solar radiation, wind load, precipitation, temperature changes, etc. Within the framework of this study, the following most significant factors have been considered: alternating electric current, ambient temperature and period of operation. These factors have been selected taking into account the possibility of conducting a multifactorial experiment and fully characterize such properties of product reliability as durability and failure-free operation. During the multifactorial analysis, the task was to select the minimum and maximum values of each factor under study, followed by the compilation of a planning matrix for a full factorial experiment. The resulting mathematical model allows us to determine the effective value of the specific volume electrical resistance of the SIW-4 insulation material depending on its operation under the given specific conditions. It also opens up the possibility of developing the second stage of the study, associated with the construction of an algorithm for the method of predictive assessment of the residual life of the insulation material of the conductor under study.

The adaptability of conductive rubber in SO2/salt spray environment was studied by using graphene-filled conductive fluoroether rubber and alloy nickel powder-filled conductive silicone rubber in“SO2/salt spray” test. The macro morphology，Shore A hardness，tensile strength，elongation at break，tear strength and volume resistivity were tested to analyze the influence of the “SO2/salt spray” environment on the properties of conductive rubber. The results show before the test，the Shore A hardness of conductive fluoroether rubber and conductive silicone rubber are equivalent，the tensile strength of conductive fluoroether rubber is higher than that of conductive silicone rubber，and the volume resistivity is lower than that of conductive silicone rubber. After 8 cycles of “SO2/salt spray” test，the macro morphology of conductive fluoroether rubber does not change，Shore A hardness decreases by 3，tensile strength increases by 0.8 MPa（5%），elongation at break decreases by 18%， the volume resistivity increases by 2.1 Ω·cm（65.8%）and there is no change in tear strength；while the conductive silicone rubber has obvious corrosion，with green corrosion products appeared on the surface，Shore A hardness gradually decreases，and the tensile strength decreases by 1.2 MPa（16.4%），the elongation at break decreases by 2%，the volume resistivity decreases by 3.00 Ω·cm（52.4%）and there is no change in tear strength. The analysis of the comprehensive performances obtained by the study shows that the adaptability of conductive fluoroether rubber in “SO2/salt spray” environment is superior to that of conductive silicone rubber.

The blending of polymers is an efficient means for developing new materials in a less hazardous and more economical way compared to the synthetic route. Polymers with different properties are blended to obtain a new material with combined properties. In this study, a thermoplastic elastomer blend is prepared by melt mixing a metallocene-based polyolefin elastomer (Engage 8003, abbreviated as EN) with linear low-density polyethylene (LLDPE, abbreviated as LL) using a twin-screw extruder in various compositions. To investigate the effect of the electron beam on the properties, LL, EN and their blends are irradiated in the 50–250 kGy dose range. The samples are subjected to gel fraction, mechanical, dynamic mechanical, hardness, heat shrinkability, volume resistivity and morphological studies. The % gel fraction, hardness and heat shrinkability of a sample increase with an increase in the irradiation dose. With increasing LL content, Young's modulus and ultimate tensile strength of the blends are increased, maintaining the % elongation at break in an attractive region. LE64 (60 wt% LL and 40 wt% EN) and LE46 (40 wt% LL and 60 wt% EN) blends show optimized mechanical and dynamic mechanical properties. Irradiation further increases the tensile strength and Young's modulus of LE64 up to 150 kGy and LE46 up to 200 kGy. The volume resistivity of the LE64 blend increases tenfold and quadruples for LE46 compared to non-irradiated blends when irradiated at 200 kGy. The morphological structures of the non-irradiated and crosslinked blends support the outcome of the obtained properties nicely. [ABSTRACT FROM AUTHOR]

Copyright of Basic Sciences Journal of Textile Universities / Fangzhi Gaoxiao Jichu Kexue Xuebao is the property of Basic Sciences Journal of Textile Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Multi-layer circuit board has the problem of poor heat dissipation performance, which limits its application in high frequency circuit. In this experiment, polytetrafluoroethylene (PTFE)/SiO2 high thermal conductivity composite film materials were prepared with Al2O3 as filler to enhance the thermal conductivity of multi-layer circuit boards. PTFE/SiO2 composite films were prepared by impregnation process combined with high temperature sintering by adding different amounts of Al2O3 into PTFE. The effects of Al2O3 content on the microstructure, density, thermal conductivity and mechanical properties of PTFE/SiO2 composite films were studied. The results show that with the increase of Al2O3 content, the thermal conductivity of the composite film shows an upward trend, and the density and mechanical strength show a trend of increasing first and then decreasing. When the Al2O3 content is 4%, the PTFE/SiO2 composite film (sample 3) has the least micro-defects, the highest density and mechanical strength, and has a reasonable thermal conductivity and electrical insulation. The density of sample 3 is 2.119 g/cm³, the mechanical strength is 17.3 MPa, the thermal conductivity is 0.98 W/(m·K), and the volume resistivity is 380.9 GΩ·m. [ABSTRACT FROM AUTHOR]

In this paper, melt blending process was adopted to add nanocalcined kaolin into flame-retardant grade ethylene vinyl acetate (EVA) copolymer, and thus, flame-retardant ethylene vinyl acetate nano-composite with high insulation property was prepared. The structure, mechanical properties and electrical properties of ethylene vinyl acetate composite were tested and characterized. The results of the tensile test showed that the tensile strength of the composite was reduced and the tensile modulus of the composite was increased after the addition of calcined kaolin; the results of the electrical properties test showed that the breakdown strength first increased and then decreased along with more addition of calcined kaolin, and the dielectric loss first decreased and then increased along with more addition of calcined kaolin, while the volume resistivity showed a continuous rising trend. The results of small-angle X-ray scattering test showed that the addition of calcined kaolin reduced the expansion range of EVA molecular chain, which was the major reason to cause the variation in electrical properties. [ABSTRACT FROM AUTHOR]

Si3N4 ceramic materials have great potential in the field of insulation in SF6 gas ultra-high-voltage transmission and transformation equipment due to their excellent insulation performance and thermal stability. In this paper, Y2O3-Al2O3 was used as a sintering aid to prepare high-density (>99%) Si3N4 ceramics through two-step pressureless liquid-phase sintering, and the mechanism of the influence of Y2O3-Al2O3 addition on the microstructure and electrical properties of Si3N4 ceramics was studied. The results showed that increasing the sintering aid content could increase the grain size of Si3N4 ceramics, while increasing the Y2O3 ratio could refine the grain size. When Y2O3-Al2O3 addition was 8% and the ratio was 5:3, the room temperature volume resistivity of Si3N4 ceramics was the highest, 7.33 × 1014 Ω·m, and the volume resistivity was the most stable when the sintering aid content was 12%. The internal carrier migration type of Si3N4 ceramics was mainly ion conduction, mainly along the grain boundaries. The temperature stability of the resistivity of Si3N4 ceramics could be improved by doping with Y3+ functional ions to reduce the potential barrier conductivity level and refine the grain size to improve the conduction path. The dielectric constant and dielectric loss of Si3N4 ceramics were mainly affected by interface polarization. They gradually increased with the increase in sintering aid addition. Temperature had little effect on dielectric constant and dielectric loss in the range of 20–80 °C. [ABSTRACT FROM AUTHOR]

Since Fe–Mn–Si–Cr shape memory alloy (Fe-SMA) has been discovered, an improvement of the shape memory effect (SME) is challenged. Numerous attempts have been made thus far to improve SME. To effectively control such performance, it becomes imperative to comprehend the real-time behavior of the stress-induced martensitic transformation (SIMT), which is strongly related to SME, during deformation. In the past, the measurement of volume resistivity has been proposed and applied to capture the forward SIMT behavior during the tensile loading process at various strain rate. However, it is quite hard to find investigations of the reverse martensitic transformation after the loading, which is more essential for understanding SME. Therefore, a comprehensive evaluation of the whole SIMT process including the loading process at various strain rate is strongly required. In this study, an improved measurement of volume resistivity is established by introducing both the four-probe and active-dummy techniques with a development of a diameter measurement at high temperature. Then, the volume resistivity of Fe-SMA is measured during the whole deformation including loading under tension at various strain rate, unloading, and heating processes. Besides, the microstructures of Fe-SMA after unloading and heating processes are observed, respectively. Finally, the real-time whole martensitic transformation in Fe-SMA is first investigated with the novel optimization method. The negative strain rate of change in volume resistivity during whole processes can be found. More amount of austenite can be obtained at lower strain rate, resulting in a larger SME.

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the results of the research, a conductive adhesive of the VK-100 grade has been developed based on a mixture of epoxy oligomers and a conductive filler, for which the powder of flake silver of ChPS-3 grade has been chosen. The properties of VK-100 conductive adhesive under the influence of artificial factors simulating operational ones have been studied. VK-100 adhesive is designed to create electrical contact in units, parts, and assemblies of the products made of aluminum and copper alloys operating in the temperature range from –60 to 100°C. [ABSTRACT FROM AUTHOR]

In this paper, we prepared ECAs (electrical conductive adhesives) with high electrical conductivity by using Ag-coated copper powder and M − II (Ti 3 C 2 T x /Ag powder) as conductive filler. M-Ⅰ (Ti 3 C 2 T x) and M-Ⅱ were prepared by acid etching and hydrothermal methods, respectively, and the electrochemical properties of M-Ⅱ and the effects of different contents of M-Ⅱ on the conductivity of ECAs were investigated. M − II has a unique reticular structure which helps to create conductive pathways, and its high specific surface area provides a large number of active sites for charge storage, resulting in increased electrical conductivity. The experimental results show that the best conductivity is achieved when the M-Ⅱ powder content is 1.2%, with a volume resistivity of 4.84 × 10−6 Ω m, at which time the Ag-coated Cu powder content is 69.8%. It has been shown in many studies that only when Ag-coated copper powder content is 70%–80%, the resistivity reaches about 10−6 Ω m. This work showed that adding a small amount of M − II and reducing the amount of Ag-coated copper powder could maintain the high electrical conductivity of ECAs. [ABSTRACT FROM AUTHOR]

The electrical properties and electromagnetic shielding effectiveness of raw, dyed and softened, and treated with an antibacterial finish polygiene VO-600 cotton/antistatic polyester fabrics of two knit patterns, such as 1 × 1 rib and half-Milano rib, giving a very similar appearance for the fabric surface and having four polyester percentages (10%, 20%, 30%, and 35%) were investigated. Surface and the volume resistivity were measured according to EN 1149, and the effectiveness of electromagnetic shielding was determined according to ASTM D4935-18. The effect of individual factors (fiber composition, knit pattern, technical side, and treatment) and their complexity on the electrical properties of fabrics was evaluated by applying analysis of variance. The research revealed that the fiber composition of fabrics as an individual factor has the greatest influence on electrical properties. Electrical resistance decreased with the increasing percentage of polyester. Half-Milano rib fabrics were significantly more resistant than 1 × 1 rib fabrics. Raw fabrics were less electrically resistant than dyed and softened fabrics, and treated with antibacterial finish fabrics. Antibacterial finished fabrics were more electrically resistant than dyed and softened fabrics. The analysis of variance revealed that the complexity of investigated factors, such as fiber composition, knit pattern, and treatment, has a significant impact on fabric resistivity for both technical sides. Therefore, when selecting knitted fabrics with a very similar appearance for final applications in daily clothing, not only the impact of individual factors on their performance must be evaluated. The shielding effectiveness of the fabrics was too low to protect against electromagnetic waves. [ABSTRACT FROM AUTHOR]

The Al2O3 3D network skeletons with layered structure were constructed by ice template method. The epoxy (EP) was successfully infiltrated into the pores of porous Al2O3 material by vacuum impregnation process, and finally the Al2O3/EP composites were prepared. The influences of wedge silicone rubber angle, slurry solid content and freezing temperature on the microstructure of layered Al2O3 3D network skeleton were investigated. And the influence of the lamellar spacing on the thermal, dielectric and insulation properties of Al2O3/ EP composites was analyzed. The results show that the order of layered Al2O3 3D network skeleton is the best with the wedge silicone rubber angle of 10° and 15°. Simultaneously, the lamellar spacing in the Al2O3 3D network skeleton decreases with the increase of solid content and the decrease of freezing temperature. The thermal conductivity and dielectric constant of Al2O3/EP composites increase with the decrease of the lamellar spacing, but the volume resistivity shows a decreasing trend. When the lamellar spacing is 45 μm, the thermal conductivity reaches 0.52 W/ (m⋅K) and the volume resistivity is 1012 Ω⋅cm. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Si3N4 ceramic materials have great potential in the field of insulation in SF6 gas ultra-high-voltage transmission and transformation equipment due to their excellent insulation performance and thermal stability. In this paper, Y2O3-Al2O3 was used as a sintering aid to prepare high-density (>99%) Si3N4 ceramics through two-step pressureless liquid-phase sintering, and the mechanism of the influence of Y2O3-Al2O3 addition on the microstructure and electrical properties of Si3N4 ceramics was studied. The results showed that increasing the sintering aid content could increase the grain size of Si3N4 ceramics, while increasing the Y2O3 ratio could refine the grain size. When Y2O3-Al2O3 addition was 8% and the ratio was 5:3, the room temperature volume resistivity of Si3N4 ceramics was the highest, 7.33 × 1014 Ω·m, and the volume resistivity was the most stable when the sintering aid content was 12%. The internal carrier migration type of Si3N4 ceramics was mainly ion conduction, mainly along the grain boundaries. The temperature stability of the resistivity of Si3N4 ceramics could be improved by doping with Y3+ functional ions to reduce the potential barrier conductivity level and refine the grain size to improve the conduction path. The dielectric constant and dielectric loss of Si3N4 ceramics were mainly affected by interface polarization. They gradually increased with the increase in sintering aid addition. Temperature had little effect on dielectric constant and dielectric loss in the range of 20–80 °C.

The investigation of conductive silver pastes and inks has witnessed extensive research within the domain of printed electronics in recent years, primarily owing to the exceptional electrical conductivity and steadfastness intrinsic to silver. This paper introduces an approach for the fabrication of stable, cost-effective, and low-resistance conductive silver paste tailored for flexible printed circuits. This method facilitates the solidification of the conductive silver paste into a highly conductive silver film at a curing temperature of 250 °C. In the process of preparing the conductive silver paste, Ag flakes is subject to modification through the incorporation of Ag NPs, which are subsequently sintered at a low temperature curing setting. The sintering of Ag NPs serves to establish connections between adjacent particles of Ag flakes within the paste, thereby enhancing the conductivity and flexibility of the resulting conductive printed silver film. When the ratio of Ag NPs to Ag flakes is maintained at 10:90, the volume resistivity of the Ag NPs-modified film registers at 2.7 × 10 ^−5 Ω.cm. This demonstrates a substantial 53.45% reduction in the volume resistivity of the conductive printed silver film modified with Ag NPs, compared to its Ag NPs-absent counterpart. Post 200 cyclic bending tests, it becomes evident that the resistance change rate in the Ag NPs-modified conductive printed silver film is a mere 12.5%, whereas the Ag NPs-modified silver film lacking Ag NPs displays a resistance change rate of 21.5%. This discrepancy underscores the capacity of Ag NPs-modified Ag flakes to fortify the bending resistance of the conductive printed silver film. Comprehensive data analysis substantiates that the improvements in electrical conductivity and bending resistance can be attributed to the superior bridging facilitated by the sintering process on the surface of the Ag NPs-modified Ag flakes.

To explore the hydration characteristics and early strength evolution of classified fine tailings cemented backfill (CFTCB), a nuclear magnetic resonance (NMR) analysis and a volume resistivity test were performed on classified fine tailings filling slurry (CFTFS). The early hydration products of CFTCB were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) phase analysis. Uniaxial compressive strength (UCS) test was carried out, and the microscopic characteristics and strength rules of the hydration reaction of CFTCB were analyzed. Based on the experiment, we found the law of water content change and porosity evolution. The early hydration reaction can be divided into the dissolution, setting, and hardening stages. The volume resistivity test results show that the volume resistance of filling slurry increases slowly at first then decreases, and finally increases rapidly. The variation trend of volume resistivity is related to the degree of hydration reaction. When combined with the hydration characteristics of backfill materials, the hydration reaction rate determines the growth rate of early strength of backfill, and the formation of hydration products is the reason for the early strength increase in backfill. The research conclusion has an important theoretical guiding value and engineering significance in mine filling production organization and filling ratio parameter optimization. [ABSTRACT FROM AUTHOR]

The poly(epoxy-N-methylaniline) conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste. Then, this was mixed with different proportions of silver powder to prepare the lowtemperature conductive silver paste. Afterwards, the effect of the conductive organic carrier on the properties of the low-temperature conductive silver paste was determined by IR, DMA and SEM. The results revealed that the prepared conductive paste has good conductivity, film-forming performance, printing performance, low-temperature curing performance, and anti-aging performance. When the mass percentage of the bonding phase/conductive phase was 40/60, the lowest volume resistivity of the conductive silver paste was 4.9 × 10-6 Ω⋅cm, and the conductivity was the best. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to the latest research, nanofluids as a possible future substitution for high-voltage equipment insulation have the potential to enhance the heat transfer and insulation properties of their base fluids. Dielectric properties are represented by breakdown strength (AC, DC, lightning) and dielectric performance as a set of quantities including dissipation factor, permittivity, and volume resistivity. In this study, natural and synthetic esters were mixed with C60 nanoparticles. Samples were examined for dissipation factor, relative permittivity, and volume resistivity at temperatures between 25 °C and 140 °C to monitor changes in dielectric performance with rising temperature, in accordance with IEC 60247. In addition, the samples were tested for AC breakdown voltage (using mushroom-like electrodes with a gap distance of 1 mm) and evaluated using the Weibull distribution statistical method. These measurements allowed complex evaluation of the examined mixtures and the determination of optimal concentration for each ester-based nanofluid. [ABSTRACT FROM AUTHOR]

Carbon nanotubes, as a successful conducting agent for power lithium ion cathode, have been applied in a large scale. Among the production of carbon nanotubes, the purification of carbon nanotubes is an important step for the application in lithium ion power battery. In this paper, physical purification, instead of chemical purification, of as-carbon nanotube soot in an Acheson furnace was investigated. The carbon nanotubes were first purified in an Acheson furnace at 3 000 °C and 2 800 °C respectively. Then, metal content, burning residue content of these purified carbon nanotubes were measured with ICP, EDS, and thermos-gravimetric analysis (TGA). And their resistivity were detected with a four-probe film resistance instrument. The micro structure and surface characteristics of these carbon nanotubes purified at different temperatures were characterized by SEM, XRD, FT-IR. The results show that the carbon nanotubes purified respectively at different high temperatures in Acheson furnace can be effectively reduced in metal content and burning residues, and these carbon nanotubes, as conductive agent can meet the requirements of power battery. Compared with the non-purified carbon nanotubes, the resistivity of carbon nanotubes purified at 3 000 °C decreases significantly and the crystallization degree of graphite increases, while the resistivity of carbon nanotubes purified at 2 800 °C increases slightly, the degree of graphite crystallization did not change much, and the quantity of their surface functional groups decreases. [ABSTRACT FROM AUTHOR]

Limiting oxygen index (LOI), flammability and electrical resistance of silicone elastomer (SiR)/alumina trihydrate (ATH) were investigated with the introduction of montmorillonite (MMT) nanoclay and chopped glass fibres (CGF). Results exhibited that MMT and/or CGF helped in improving the LOI and flame-retardant ability of SiR/ATH30. LOI of SiR/ATH30 was measured at 30% whilst it improved to 31% and 34% in MMT and/or CGF-filled composites. Interestingly, CGF offered better fire resistance to SiR/ATH30 than MMT. Moreover, the joint addition of MMT and CGF in the SiR/ATH30 exhibited the most improved flammability resistance. MMT/CGF slightly reduced the volume resistivity of SiR/ATH30 whereas, it is still measured as higher relative pristine SiR. Among all, SiR/ATH30/MMT5/CGF3 appeared a most promising candidate relatively with the peak heat release rate (pHRR), peak rate of smoke release (pRSR), peak mass loss rate (pMLR) and volume resistivity of 144.6 kW/m2, 1.53 (m2/s)/m2, 0.0436 g/s and 5.6 × 1010 Ω•cm. [Display omitted] [ABSTRACT FROM AUTHOR]

In this article, a flame-retardant ethylene-vinyl acetate copolymer (EVA) hot-melt adhesive for quickly repairing aging cables was prepared, and the aluminum diethylphosphinate, dimelamine pyrophosphate and aluminum hydroxide were selected as flame retardant additives. EVA hot melt adhesive passed UL 94 V-0 rating without dripping and the limiting oxygen index was 27.1 vol% when the total loading amount of flame retardants was 50 wt% with the mass ratio of the above three flame retardants was 1:1:3. Compared with the pure hot melt adhesive, the heat release rate and total heat release of the prepared flame retardant hot melt adhesive was greatly reduced, and the flame retarded system exerted excellent synergistic flame retardant effect. The volume resistivity of the repaired cable reached 3.12x1015 Ω⋅m. Moreover, the hot-melt adhesive exhibited excellent film-forming and adhesion on cable surface, and it will not crack or fall off during the bending process of the repaired cable. The intumescent char layer is generated on the cable surface and it can effectively protect the cable during combustion. [ABSTRACT FROM AUTHOR]

The addition of various oxide dopants for AlN were investigated aiming to increase the AlN volume resistivity at high temperature. It was confirmed that the volume resistivity of 1 mol% MgO doped AlN shows four orders of magnitude higher than that of non-doped AlN. To further clarify the effect of MgO doping, we sintered various kinds of AlN with different MgO concentration and grain sizes, and the microstructures were investigated by transmission electron microscopy. The results suggest the inversion domain boundary appeared in the MgO doped AlN might be the possible reason for the increase of volume resistivity. [ABSTRACT FROM AUTHOR]

Copyright of Basic Sciences Journal of Textile Universities / Fangzhi Gaoxiao Jichu Kexue Xuebao is the property of Basic Sciences Journal of Textile Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the effect of doping hexagonal boron nitride (h-BN) on the thermal properties and insulation resistance of epoxy resin (EP) and the mechanism of this effect, h-BN/epoxy composites with h-BN content of 0, 10, 20, 30, and 40 phr were prepared. Meanwhile, the corresponding molecular dynamics model of h-BN/epoxy composites was established, and the thermal conductivity, volume resistivity, glass transition temperature, and microstructure parameters of h-BN/epoxy composites were obtained. When the h-BN content is 40 phr, the thermal conductivity of h-BN/epoxy composite is increased by 138% compared to pure EP, and the glass transition temperature is increased by 76 K. At the same time, doping h-BN will reduce the insulation performance of EP. However, the lowest volume resistivity of h-BN/epoxy composite is still 1.43 × 1015 Ω·cm, and the EP composite still has good insulation performance. The fraction free volume and mean square displacement of EP decrease with the doping of h-BN, which indicates that h-BN can hinder the movement of molecular segments of EP, which is the reason for the increase in glass transition temperature.

Carbon based materials with excellent conductivity such as conductive carbon black, graphene, and carbon nanotubes (CNTs) are often used in the preparation of conductive polymer composites. Pyrolysis carbon black, as a recycled material of waste rubber, can be used as a substitute for other carbon black in some fields, which can greatly reduce the production cost and promote reuse of used rubber. In this article, pyrolysis carbon black is mixed with CNT and added to natural rubber by mechanical blending method to get the composite material. The synergistic effect of pyrolysis carbon black and CNT, 3D network structure and formation of conductive network are investigated, and the properties of composites are analyzed. The results show that the 3D "grape cluster" network structure formed by the synergistic action of the pyrolysis carbon black and CNT, which led to the improvement of the curing properties and mechanical properties of the composites, increase the Payne effect, decrease the dispersion of the filler, and significant reduction the volume resistivity of the composites. With the increasing of CNT content, the variation of the properties of the composites changed and stabilized. In general, when 40 phr pyrolysis carbon black and 4 phr CNT are mixed into rubber matrix, the composite has the best comprehensive performance, and the volume resistivity is 9.25E5. Our results provide new thoughts in preparing natural rubber conductive composites. By adding highly CNT and inexpensive pyrolysis carbon black, the problem of easy aggregation of a single filler is overcome, which is more economical than adding two highly conductive fillers, and the process is simpler and time‐saving compared to the modified solution. More studies need to be done in order to reveal the effects of pyrolysis carbon black in practical conductive composites. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carbon nanotube （CNT） reinforced natural rubbery were prepared by rubber-latex mixing method, in which ball-milling dispersion and ultrasonic dispersion were used for CNT dispersion strengthening, and we have studied these methods on effects of processability and mechanical property and thermal conductivity and volume resistance and DIN abrasion. Results showed that compared to ultrasonic dispersion, CNT in ball-mill samples have shorter length with less twists and well dispersibility; the curing rate of ball-mill sample is faster than of ultrasonic sample, and vulcanization reaction in ball-mill samples are more sufficient; both ball-milling and ultrasonic dispersion are good for increasing tensile strength; ball-mill dispersion is superior to ultrasonic dispersion in terms of increasing thermal conductivity and decreasing volume resistance; DIN abrasion of ultrasonic samples are less than of ball-mill samples. [ABSTRACT FROM AUTHOR]

The results of the search and analysis of information in the field of modern foreign conductive adhesives (mainly silver-containing ones) are presented and their main properties, as declared by the developers, and information on their application are presented. To compare the level of characteristics of conductive adhesives, some of their values have been transferred by the authors into the same dimension, which differs from the dimension presented in the original source. [ABSTRACT FROM AUTHOR]

The addition of conductive fillers to the carbon fiber bar reduces its resistivity and improves electrical stability. Unstable conductivity and susceptibility to ambient temperature change impede the application of this technique in engineering, unless such influence can be eliminated by technical means or precisely predict. In this paper, modified epoxy Resin based carbon fiber bars with 4 sets of different mixed fillers have been designed to evaluate the temperature-resistance effect under different temperature cycles. Results show that the initial volume resistivity reduces due to the incorporation of carbon powder(CP) and nano-silica(NS), and meets the lowest when the CP and NS mass ratio is 1:0.6. The volume resistivity increases linearly with the temperature rising, and reaches the maximum temperature sensitivity coefficient of 78.8%. During the temperature cycle process, the volume resistivity of all specimens first decreases and then increases with the increasing temperature uniformly. The three groups (CP/NS ratio 1:0.2, 1:0.6, and 1:0) share the same PTC effect transition temperature range, from 30 to 60 °C. And for the 1:1 group, the transition temperature is about 0 °C, which is the lowest. Altogether, these enhancements provide avenues for future self-sensing carbon fiber composites in engineering structures.

Copyright of Issues of Chemistry & Chemical Technology / Voprosy Khimii & Khimicheskoi Tekhnologii is the property of Ukrainian State University of Chemical Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ceramizable silicone rubber composites were prepared by the melting blending method. The tensile properties, flame retardant property, and volume resistivity of the silicone rubber composites were tested. The results show that the tensile property of composites decline with the increasing flux amount. The introduction of more impurity ions improves the conductivity of the composites. The addition of SiO2 enhances the compactness of the filler network structure, and the elastic deformation and the tensile strength of the composites are also increased. The migration of carriers is hindered, which promotes the increase of volume resistivity of composites. Because of the synergistic effect of a variety of inorganic fillers, composite materials have a better flame retardant property. When the part of weight of glass powder and SiO2 is 40: 40, the oxygen index of the composites is the highest, meanwhile, the peak heat release rate and the peak smoke production rate are the lowest, and the fire risk is smaller. The blending of EVA and silicone rubber improves the rigidity and plastic deformation of the composites, and also changes the dispersion state of the fillers. The partially stacked fillers act as impurity ions, which causing the resistivity of the materials to decrease. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper deals with the evaluation of the amount of filler influence and the ultraviolet (UV) radiation influence on selected dielectric properties of the innovative type of composites. These composites consist of a linear low-density polyethylene matrix and a clay filler (with different filling levels) that contains halloysite nanotubes (HNT) primarily. The intended application of tested composites in the field of electrical engineering is in insulating systems of power cables. Attention is paid to the analysis of the behaviour of composites in their charging, which is caused by the connection with the direct voltage source. The volume resistivity and polarization indexes are determined based on this analysis. Analysis of charging based on the measurement of the current, which flows through the sample under constant applied voltage, is supplemented with the short evaluation of the material behaviour after the disconnecting of the voltage source and after the electrode shorting when the material is discharged. Furthermore, the measurement of dielectric strength under an alternating electric field as another key parameter of electrical insulating materials is determined. Results of analyses of absorption and resorption processes and the dielectric strength measurement of materials in the delivered state prove a significant effect of the filler percentage in the composite. Subsequently, markedly different values of selected parameters because of material exposure to UV radiation are also determined. Observed changes in dielectric properties caused by UV irradiation are supported by the analysis of the chemical structure of materials via Fourier transform infrared spectroscopy.

High quality graphene and its epoxy composites were prepared by exfoliation of first stage FeCl3-GICs with sodium borohydride (NaBH4) aqueous solution, followed by compounding with epoxy resin. First stage FeCl3-GICs were prepared by compounding anhydrous FeCl3 and graphite at 330℃. XRD analysis and scanning electron microscopy data show that the interlayer spacing of graphite intercalation compounds is increased from 0.335nm to 0.930nm,indicates first stage FeCl3-GIC is obtained. Transmission electron microscopy shows single layer grapheme is made. Raman spectroscopy and XPS data show that the graphene's ID/IG=0.09,C/O=40.80, comparing that of flake graphite's ID/IG=0.17 and FTIR spectra, suggesting that NaBH4 exfoliation can simultaneously repair the structural defects of flake graphite. Characteristic peaks of C=O(1735cm-1),C-O(1228cm-1)are found in FTIR spectra of flake graphite, while no functional groups characteristic peaks of graphene shows up in the corresponding locations, indicating that hydrogen produced by sodium borohydride successfully reduces oxygen from graphite makes the graphite more complete structure. The conductivity of composites gradually increases with the increase of graphene content, and the volume resistivity decreases from the pure epoxy resin of 1.95×1013Ω·cm to 3.41×105Ω·cm when the volume fraction is 3.70%. The conductivity of the composites increases by 8 orders of magnitude.SEM images of fracture morphology shows some incompatibility exists between graphene and epoxy resin.

This article reports on the development of nano-MgO/epoxy resin composites with various mass ratios via a solution blending method. The influence of MgO nanofillers on the thermal properties and the effect of environmental temperature on the insulating properties of the composite material were analyzed. The results show that the thermal conductivity of the composites increased with an increasing MgO nanofiller content. Compared with the pure epoxy resin, the thermal conductivity increased by 75% when the content of MgO nanoparticles was 7%. The volume resistivity first increased and then decreased with an increasing doping concentration. The volume resistivity increased by 26.8% in comparison with the pure epoxy resin when the content of MgO nanoparticles was 1%, while its dielectric constant and dielectric loss increased with temperature. In addition, the dielectric constant increased and the dielectric loss first decreased and then increased with an increasing MgO nanoparticle content. Moreover, the MgO composites changed from a glassy to a rubbery state, and the breakdown strength was significantly reduced with an increased temperature. When the temperature was higher than the glass transition temperature, the breakdown strength decreased by 51.3% compared with the maximum breakdown strength at 20 °C. As the content of MgO nanoparticles increased, the breakdown strength of the composite first increased and then decreased. The highest breakdown strength was achieved when the content of MgO nanoparticles was 1%, which was 11.1% higher than that of the pure epoxy resin. It was concluded that the MgO nanofillers can significantly improve the thermal properties of epoxy composites and their insulation performance at high temperatures. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) modified with silane coupling agent A-1120 (MWCNTs-A1120) were prepared. Compared with the raw MWCNTs, acidified MWCNTs (MWCNTs-COOH), and MWCNTs grafted with EDA (MWCNTs-NH2), MWCNTs-A1120 have the best dispersion in fluoroelastomer at the same doping ratio. Therefore, fluoroelastomer/MWCNTs-A1120 composite has the best mechanical properties with tensile strength of 13.92 MPa and elongation at break of 111.78%. Then, the effects of doping amount of MWCNTs-A1120 on the electrical properties of the composites were investigated. The dielectric constant of the composite increases with the increase of MWCNTs-A1120, and the dielectric loss does not change much at the low doping amount such as 0.5 wt%. When the doping amount of MWCNTs-A1120 is 5 wt%, the dielectric constant and the dielectric loss value are greatly increased, and the volume resistivity is greatly decreased, which proves that the conductive network is formed in the composite, so the filling amount of 5 wt% is the percolation threshold. The tensile deformation of the sample also affects the electrical properties of the composites. As the tensile deformation increases, the dielectric constant and dielectric loss of the composite decrease. For the composite with 5 wt% MWCNTs-A1120, excessive tensile deformation will destroy the conductive network structure of the composite, so the composite will change from conductive material to dielectric material. Therefore, such composite is a good candidate for flexible conductive material or flexible dielectric material used in harsh environments such as high temperatures and various aggressive solvents. [ABSTRACT FROM AUTHOR]