Quasi-optical measurement of complex dielectric constant at 300 GHz

A two beam interferometer in the Martin-Puplett configuration is used to determine the complex dielectric constant at 300 GHz of teflon, TPX-plastics, SPECTRALON and paraffin waxes with melting temperatures of 48° C and 72° C, respectively. The design of the quasi-optical system leads to a constant beam diameter at the power detector independent of path delay and frequency. The power detector signal is recorded not only along one period but over about 50 periods. A spectrum estimation routine allows to determine more exactly amplitude and phase angle of the signal. A basic problem is noticed: imperfect detector and source match cause harmonic distortion of the power detector signal. The effects on processing the loss tangent and the invalidation are shown. Finally loss tangent and dielectric constant are determined indirectly by optimizing an equivalent microwave circuit using a commercial available microwave design system to take multiple reflections and losses in consideration.     

纳米Sb2O3及其在云母表面的组装与阻燃性能

纳米Sb2O3及其在云母表面的组装与阻燃性能;Sb2O3; 纳米微粒; 云母; 阻燃; 氯化石蜡     

硼酸酯对ZDDP和氯化石蜡减摩抗磨性能的影响

通过摩擦学性能测试和摩擦表面膜成份的ｘ－射线能量色散谱（ＥＤＳ）分析，研究了硼酸酯同氯化石蜡和二烷基二硫代磷酸锌（ＺＤＤＰ）相互作用机理。试验结果表明；硼酸酯具有良好的减摩效果。氯化石蜡含量影响其与硼酸醒的相互作用效果。石油磺酸钙用作分散剂使硼酸酯的抗磨性能变差，ＺＤＤＰ与硼酸酯在摩擦过程中互相竞争金属表面，从而改善硼酸酯的抗磨性，硼酸酯，氯化石蜡，ＺＤＤＰ之间在减摩抗磨性能方面产生“协同效应。     

Aspects of crystallization fouling

Crystallization fouling or scale formation is temperature dependent, and a degree of supersaturation is required before precipitation occurs. In general, a nucleus is necessary around which crystals can form. The mechanism of crystallization on surfaces is complex, and it is difficult to explain in mathematical terms, although attempts have been made. The paper concludes with a brief review of scale formation under boiling conditions and the deposition of wax crystals from organic liquids.     

Study of Transition States of Melamine for Micromixing with Wax Emulsion+4‐Nonyl Phenol Ethoxylate,Estimated with SEM Technique

Densities (ρ/10³kg m^?3), apparent molar volume (V₂/10^?6m³mol^?1), and viscosities (η/0.1 kg m^?1s^?1) for 5.0 to 60.0 millimol kg^?1 (m mol kg^?1) 1,3,5 triazine (melamine) at interval of 5.0 m mol kg^?1 were determined. The data were regressed and extrapolated to infinite dilution (m→0) and referred to as limiting apparent molal volume (V¯₂ ⁰) and intrinsic viscosity (B) and used to calculate free energy of activation (Δµ₂ ^0*/KJ mol^?1). Such functions illustrate feasibility of micromixing of melamine with paraffin wax emulsifier+4‐nonyl phenol ethoxylate, a nonionic surfactant in aqueous solution. The Δµ₂ ^0* decides micromixing of melamine stabilized by poly(acrylic acid) of 4500 g mol^?1 molecular weight, known as superabsorber for water. Paraffin wax emulsion was stabilized by a nonyl phenol ethoxylate and wax particles observed to adhere to melamine surface due to interactions between poly(acrylic acid) dispersant and ethoxylate group of surfactant, resulting in sedimentation of mixed particles. Thus V¯₂ ⁰, B, and Δµ₂ ^0* values conclude to ‐NH₂ group interactions for micromixing and scanning electron micrograph (SEM) elucidates microstructure and uniformity of micromixing.     

Use of water in aiding olefin/paraffin (liquid + liquid) extraction via complexation with a silver bis(trifluoromethylsulfonyl)imide salt

This paper describes the extraction of C₅–C₈ linear α-olefins from olefin/paraffin mixtures of the same carbon number via a reversible complexation with a silver salt (silver bis(trifluoromethylsulfonyl)imide, Ag[Tf₂N]) to form room temperature ionic liquids [Ag(olefin)_x][Tf₂N]. From the experimental (liquid + liquid) equilibrium data for the olefin/paraffin mixtures and Ag[Tf₂N], 1-pentene showed the best separation performance while C₇ and C₈ olefins could only be separated from the corresponding mixtures on addition of water which also improves the selectivity at lower carbon numbers like the C₅ and C₆, for example. Using infrared and Raman spectroscopy of the complex and Ag[Tf₂N] saturated by olefin, the mechanism of the extraction was found to be based on both chemical complexation and the physical solubility of the olefin in the ionic liquid ([Ag(olefin)_x][Tf₂N]). These experiments further support the use of such extraction techniques for the separation of olefins from paraffins.     

添加碱土金属对负载型铂锡催化剂长链烷烃脱氢反应性能的影响

用微型催化反应装置结合吡啶吸附 红外光谱、热重、氢化学吸附和程序升温等还原手段,研究了添加碱土金属离子助剂对负载型PtSn/γ-Al2O3催化剂长链烷烃(C10~13)脱氢反应性能的影响。结果表明,碱土金属助剂的引入可以降低催化剂积炭量、提高催化剂铂金属表面裸露度,从而提高催化剂脱氢反应稳定性。但强碱性的碱土金属助剂如Ba2+的引入增强了锡与载体之间的相互作用,减弱了锡与铂之间的相互作用, 导致反应后催化剂铂金属表面裸露度下降,故PtSnBa/γ-Al2O3催化剂脱氢活性较低。     

低温高活性熔铁催化剂上的超临界相费托合成反应

在固定床反应器中超临界相条件下研究了熔铁催化剂上的费托合成反应,发现在超临界介质中反应物和产物更容易扩散,较好地抑制了催化剂表面非活性碳的沉积,从而提高了费托合成反应中的CO转化率和烯烃选择性,增加了链增长因子,降低了甲烷选择性.同时,考察了超临界介质、反应温度、压力、H2/CO比和空速等条件对费托合成反应的影响.结果表明,C5-8正构烷烃在催化剂活性温度下都是适宜的超临界介质.当温度和压力都在介质的临界点以上时,介质表现出较好的传质与传热性能,可改善费托合成反应性能.     

Thermal-Conductivity-Enhancing Copper-Plated Expanded Graphite/Paraffin Composite for Highly Stable Phase-Change Materials

Paraffin (PA)/expanded graphite (EG) is an important composite phase change material with low cost, high heat storage, good thermal conductivity and cycling stability. Its thermal conductivity needs to be further improved for application in the thermal management system of power lithium-ion batteries. In this paper, copper plated expanded graphite (CPEG) with 3D porous structure was prepared by electroless copper plating method, which was used as thermal conductivity enhancing material to replace part of EG in PA/EG composite materials. For the optimized phase change material composed of 80 %PA-14 %EG-6 %CPEG, the copper content is very low (0.768 wt %), but its thermal conductivity can be significantly improved without loss of latent heat and thermal cycling stability. Its thermal conductivity is increased from 11 times to 16.5 times that of paraffin while compared with the copper-free composite material (80 %PA-20 %EG). The PA/EG/CPEG composite material exhibits good temperature control effect on power lithium-ion batteries.     

Synergistic effect between surfactants and polyacrylates-maleicanhydride copolymers to improve the flow properties of waxy crude oil

Four copolymers were prepared by copolymerization of octadecyl acrylate with maleic anhydride abbreviated as [ODM], the resulted copolymer was reacted with octadecylalcohol [ODMSA], hexadecylamine [ODMCA], benzyl alcohol [ODMBA] and aniline [ODMAn]. Three oil-soluble surfactants were also prepared by esterification of mono, di and tri ethanolamine with oleic acid, abbreviated as [MEAO, DEAO and TEAO]. These compounds were purified and characterized by FTIR, ¹H-NMR and GPC. The prepared copolymers were evaluated individually and mixed with the oil-soluble surfactants and evaluated as flow improvers and pour point depressants for waxy crude oil. It was found that, the polymer with aromatic side chain [ODMBA] exhibited the maximum pour point depression ΔPP?=?24°C at concentration 1000?ppm, while the minimum pour point depression was obtained by [ODMCA] which pronounced ΔPP?=?15°C at 1000?ppm. Furthermore, the blend [B4] between [ODMBA] and oil-soluble surfactant [TEAO] achieved extra depression of pour point (ΔPP?=?30°C). The rheological properties of the treated and untreated crude oil with the polymeric additives were also investigated and it was found that Bingham yield value (τ_B) was decreased from 1.63?Pa at 32°C to 0.3?Pa at the same temperature and 500?ppm concentration of [ODMBA].