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1.
Achieving precise control over the synthesis and properties of porous nanostructured materials has been garnering considerable recent research attention. In the work presented here, nickel oxalate nanostructures with controllable shapes were synthesized through a simple and facile wet-chemistry route without any surfactant. An interesting shape evolution process from 2D nanoflakes to 1D nanorods has been illustrated on the basis of time-dependent experimental studies. Subsequent calcination at 380 °C yielded porous NiO nanostructures that retained the morphologies of their predecessors. The phase composition, morphology, and structure of the as-obtained products were studied by various tools. Electrochemical properties of the NiO electrodes were carried out using cyclic voltammetry and galvanostatic charge–discharge measurements by a three-electrode system. Electrochemical studies reveal that the as-prepared mesoporous NiO nanostructures have good specific capacitance and exhibit excellent capacity retention for more than 1,000 cycles due to its porous character and morphology. The results suggest that mesoporous NiO nanostructures are a promising supercapacitor electrode material.  相似文献
2.
A series of polyurethane (PU)/talc composites modified by a high molecular weight hydroxyl-terminated polydimethylsiloxane (HTPDMS) were prepared. The effect of the talc content on the mechanical, wettability and tribological properties of the PU composites was studied. Tensile strength of the PU composites reached to the maximum after adding 5% talc. The water contact angles (CA) of the original surfaces and worn surfaces of the polyurethane composites were measured. The experimental results indicated that the contact angles of the worn surface increased after friction. The friction and wear experiments were tested on a MRH-3 model ring-on-block test rig at different sliding speeds and loads under dry sliding and water lubrication. Experimental results revealed that the talc contributed to largely improve the tribological properties of the PU composites. The coefficient of friction (COF) of the composites increased with increasing talc. Scanning electron microscopic (SEM) investigations showed that the worn surfaces of the talc filled PU composites were smoother than pure polyurethane under given load and sliding speed.  相似文献
3.
A series of superhydrophobic polytetrafluoroethylene (PTFE) surfaces were prepared by a facile cold pressing and sintering method, and their microstructures and wetting behaviors could be artificially tailored by altering sintering temperature and using different masks. Specifically, the microstructures mainly depended on the sintering temperature, whereas the wetting behaviors, water contact angle (WCA) and sliding angle (SA), greatly hinged on both the sintering temperature and mask. Then a preferable superhydrophobic surface with WCA of 162 ± 2° and SA of 7° could be obtained when the sintering temperature was 360 °C and the 1000 grit abrasive paper was used as a mask. In addition, it was worth noting that the as-prepared surfaces exhibited excellent stability under UV illumination, which was the most key factor for them toward practical applications.  相似文献
4.
The present work reports a simple method to produce the aluminum superhydrophobic surface based on an interface reaction between an aluminum foil and zinc aqueous solution. The products were characterized by field-emission scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectrum. The field-emission scanning electron microscopy images show that the coating surface is composed of micro/nanoscale binary structure, which is similar to the structure of lotus leaf. The wettability of the coating surface was also investigated. It was found that after treatment with stearic acid, the wettability of the aluminum foil changed from superhydrophilic to water-repellent superhydrophobic. The complex micro/nanoscale binary structures along with the low surface energy lead to the high surface superhydrophobicity.  相似文献
5.
Carbon fibers-reinforced polyimide composites (CF-PI) were fabricated by means of a hot press molding technique. To contrast the effects of ultraviolet and atomic oxygen irradiation under high vacuum on the tribological properties of CF-PI composites, the friction and wear properties of the composites sliding against GCr15 steel ball before and after irradiation were conducted in high vacuum on a ball-on-disk test rig. The experimental results revealed that CF-PI composites exhibited higher modulus and lower coefficient of friction and worn rate value than pure polyimide under high vacuum. However, the coefficient of friction of composites increased and the worn rate value decreased after ultraviolet or atomic oxygen irradiation, which slightly affected the tribological properties of CF-PI composites. The chemical composition of the composites changed after irradiation was inspected by X-ray photoelectron spectroscopy. Microstructure of the worn surfaces of the tested composites was investigated by scanning electron microscopy to reveal the wear mechanism.  相似文献
6.
Polyimide composites filled with aramid fiber (AF) and polytetrafluoroethylene (PTFE) were prepared by hot press molding. The thermal, mechanical, and tribological properties of the composites were studied systematically. The friction and wear behavior, sliding against GCr15 steel balls, were evaluated in a ground-based wear in space simulation facility using a ball-on-disk tribosystem. The morphologies of the worn surfaces during the sliding process of the composites were analyzed by scanning electron microscopy to reveal the wear mechanism. It was found that the heat-resisting performance and the hardness of the composites were minimally affected by the additives. The flexural strength of polyimide/AF/PTFE (PI-3) decreased when PTFE was added. The wear resistance increased and the coefficient of friction decreased due to the effect of both fillers. In vacuum, the friction coefficients of polyimide (PI-1), polyimide/AF (PI-2), and PI-3 increased slightly with sliding velocity, while the opposite results were obtained in air. With the increase of air pressure the friction coefficients of the samples increased.  相似文献
7.
A series of castor oil-based polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by two kinds of hydroxy-terminated liquid nitrile rubber (HTLN) was prepared. A systematic investigation of the tribological properties of the two kinds of HTLN-modified PU/EP IPN composites was carried out through a pin-on-disk arrangement under dry sliding conditions. Experimental results revealed that the incorporation of HTLN can improve the friction and wear properties of PU/EP IPN significantly. Both the friction coefficient and wear loss decreased with increasing content of HTLN. The worn surfaces of the samples were analyzed using scanning electron microscope and a three-dimensional (3D) noncontact surface-mapping profiler; the results showed that the worn surfaces of the PU/EP IPN composites became smooth when the HTLN was added. The mechanisms for the improvement of tribological properties are discussed.  相似文献
8.
Nanoflakes-built pyrite FeS2 microspheres were synthesized through a simple solvothermal process in mixed solvents of N, N-dimethytformamide and ethylene glycol without using any surfactant. Both the composition of the solvents and urea were key factors for the formation of the uniform products. It was found that the flake-like intermediate products transformed into FeS2 nanoflakes in situ in the early stage and Ostwald ripening growth mechanism would contribute to the uniformity of the final products. Electrochemical studies revealed that the nanoflakes-built pyrite FeS2 microspheres exhibited large lithium storage capacities. This method can be easily controlled and is expected to be extendable to the fabrication of other metal chalcogenides with controlled shape and structure.  相似文献
9.
A series of polyurethane (PU) samples based on poly(tetramethylene glycol)/epoxy resin (EP) graft interpenetrating polymer networks (IPNs) were prepared and their damping, thermal, and mechanical properties were systematically studied in terms of composition and the value of the PU isocyanate index (R). The damping properties and thermal stability measurements revealed that the formation of PU/EP IPN could improve not only the damping capacity but also the thermal stability. Meanwhile, mechanical tests showed that the tensile strengths of the IPNs decreased while their impact strengths increased with increasing PU content. The value of R also had significant impacts on the properties of the IPNs when the PU and EP ratio was fixed, which could be an effective means for manipulating the fabrication of PU/EP IPNs. The morphologies of the PU/EP IPNs were observed by SEM and AFM characterization and the relationship between the morphologies and properties is discussed. With the results in hand, the PU/EP IPNs hold promise for use in structural damping materials.  相似文献
10.
A series of polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by a high molecular weight hydroxyl-terminated polydimethylsiloxane (HTPDMS) were prepared. The effects of HTPDMS content on the phase structure, damping properties and the glass transition temperature (Tg) of the HTPDMS-modified PU/EP IPN composites were studied by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). Thermogravimetric analysis (TGA) showed that the thermal decomposition temperature of the composites increased with the increase of HTPDMS content. The tensile strength and impact strength of the IPN composites were also significantly improved, especially when the HTPDMS content was 10%. The modified IPN composites were expected to be used as structural damping materials in the future.  相似文献
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