通过扫描电子显微镜观察了天然橡胶和高吸水树脂共混体系的微观相态结构 ,研究了两亲性嵌段共聚物PEO b PBA结构本身的吸水能力对天然橡胶和高吸水性树脂共混体系吸水性能及力学性能的影响。结果表明 ,PEO b PBA结构本身的吸水强弱对共混体系的吸水能力贡献很小 ,但却可以显著提高共混体系的吸水膨胀能力和力学性能 ,对特殊的增容作用进行了探讨 相似文献
Electrochemical water-splitting is widely regarded as one of the essential strategies to produce hydrogen energy, while Metal-organic frameworks (MOFs) materials are used to prepare electrochemical catalysts because of its controllable morphology and low cost. Herein, a series of trimetallic porous Pt-inlaid Ni–Fe nanocubes (NCs) are developed with bifunctions of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In the process of prepare the electrochemical catalysts, Pt nanoparticles are uniformly embedded in the Fe–Ni PBA cube structure, and ascorbic acid is employed as a reducing agent to reduce Pt2+ to Pt nanoparticles. In this work, the cubic structure of Fe–Ni PBA is maintained and the noble metal Pt nanoparticles are embedded. Remarkably, the formation of PBA cubes, Pt inlay and reduction are completed in one step, and Pt nanoparticles are embedded by a simple method for the first time. By employing acid etching method, a porous structure is formed on the PBA cube, which increases the exposed area of the catalyst and provides more active sites for HER and OER. Due to the porous structure, highly electrochemical active surface area and the embedded of highly dispersed Pt nanoparticles, the porous 0.6 Ni–Fe–Pt nanocubes (NCs) exhibits excellently electrocatalytic performance and durable stability to HER and OER. In this work, for HER and OER, the Tafel slopes are 81 and 65 mV dec−1, the overpotential η at the current density of 10 mA cm−2 are 463 and 333 mV, and the onset potential are 0.444 and 1.548 V, respectively. And after a 12-h i-t test and 1000 cycles of cyclic voltammetry (CV), it maintained high stability and durability. This work opens up a new preparation method for noble metal embedded MOF materials and provided a new idea for the preparation of carbon nanocomposites based on MOF. 相似文献
A proper mathematical representation of uncertainties is indispensable for reliability analysis of a practical engineering structural system. A general uncertainty analysis approach is probability bounds analysis (PBA), which propagates constraints on a distribution function through mathematical operations. The uncertainty about a probability distribution is represented by the set of cumulative distribution functions lying entirely within a pair of bounding distribution functions, which is called a P-box. Interval analysis as a special case of PBA is useful when there is no or less probabilistic information. It is common sense that great efforts must be paid to get enough probabilistic information used for probabilistic analysis of large and complex engineering structural systems. Even if there is no or less probabilistic information; the interval of possible values of probability of an event can be easily specified, such as the interval value of each element’s reliability of an engineering structural system.
This paper aims to introduce the concept of system reliability and its relationship to the reliability of its individual elements in an interval form. In terms of extension principle, interval arithmetic and possibility degree formula (PDF) for ranking interval numbers, basic properties of system reliability in interval form are investigated. The conclusion is that relationships between point reliability (point reliability used to describe a precise value of probability reliability is distinct with interval reliability) of some typical systems, such as series system, parallel system, series–parallel system, parallel–series system and r/n(G) system, etc., and point reliability of their individual elements are maintained in their interval forms. This is called quasi-consistency in this paper. A simple review of order relations of interval numbers, which will play an important role in interval reliability analysis, is given. The proposed quasi-consistency establishes the foundations for interval reliability analysis of a complex engineering structural system. 相似文献
The nanoparticles of Mn1.5[Cr(CN)6]∙mH2O@Ni1.5[Cr(CN)6]∙nH2O core-shell prussian blue analogues (PBA) embedded with carbon additives (PBA-C) were synthesized and characterized as electrode material for solid state battery application. The impedance spectroscopy and cyclic voltametry were used to study the electrochemical properties by adding functionalized carbon in 1:1 proportion to improve the electrical performance. The value of room temperature electrical conductivity of core-shell PBA and core-shell nanoparticles mixed with vulcan carbon (PBA-C) are found to be 1.574 × 10−3 and 1.92 × 10−3 Scm−1, respectively. Using Li7La3Zr2O12 (LZZO) electrolyte, single cell was fabricated with PBA-C material, and studied its charging-discharging cycles, which exhibits higher current density with stable performance for 400 cycles for time slots of 400 min. The study reveals that the PBA core-shell nanoparticles mixed with carbon (PBA-C) may be a potential candidate as an electrode material in the form of a single cell using LZZO electrolyte. 相似文献