新型三联季铵盐表面活性剂的合成与性能研究

本文合成了一种三聚阳离子表面活性剂—三(2-氯化十二烷基二甲铵基乙基)胺(TCDAEA)。以三乙醇胺、氯化亚砜为原料,经分子内亲核取代合成了中间体三(2-氯乙基)胺并通过乙酰化法测定其转化率;然后以三(2-氯乙基)胺与N,N-二甲基十二烷基叔胺经季铵化反应合成了TCDAEA。并通过单因素条件实验考察了催化剂质量分数、反应温度、反应时间、溶剂质量分数、N,N-二甲基十二烷基叔胺与三(2-氯乙基)胺物质的量比等因素对产品产率的影响及其对产品溶液表面张力的影响。结果表明：当氢氧化钾质量分数为0.3%、nN,N-二甲基十二烷基叔胺：n三(2-氯乙基)胺=3.9、溶剂质量分数为20%、反应温度为80℃、反应时间为6h时,产品收率可达96.56%;在上述条件基础上,在25℃、临界胶束浓度为4.2?0-4mol/L时,产品溶液的表面张力降低至25.2mN/m。此外,用FT-IR方法对中间体和产物TCDAEA进行了分析表征,研究表明,TCDAEA是一种新型的三聚季铵盐阳离子表面活性剂,具有更高的表面活性。     

A new interpolation method for Antarctic surface temperature

We propose a new methodology for the spatial interpolation of annual mean temperature into a regular grid with a geographic resolution of 0.01° for Antarctica by applying a recent compilation of the Antarctic temperature data.A multiple linear regression model of the dependence of temperature on some geographic parameters (i.e.,latitude,longitude,and elevation) is proposed empirically,and the kriging method is used to determine the spatial distribution of regional and local deviations from the temperature calculated from the multiple linear regression model.The modeled value and residual grids are combined to derive a high-resolution map of surface air temperature.The performance of our new methodology is superior to a variety of benchmark methods (e.g.,inverse distance weighting,kriging,and spline methods) via cross-validation techniques.Our simulation resembles well with those distinct spatial features of surface temperature,such as the decrease in annual mean surface temperature with increasing latitude and the distance away from the coast line;and it also reveals the complex topographic effects on the spatial distribution of surface temperature.     

The thin-wall debit of a typical cast polycrystalline M951 alloy

The effect of specimen thickness on the rupture properties of cast Ni-based polycrystal superalloy M951 was investigated in this paper. The results of the rupture tests in air under 980 ?°C/90 ?MPa revealed that the rupture life and elongation obviously decreased with decreasing specimen thickness. The thin-wall effect for polycrystal superalloy M951 is associated with several factors. First, the surface oxidation and internal nitridation induce the reduction in the load-bearing section, which accelerates the rupture fracture of thin specimens. Second, the combined effect of oxidation and stress at the surface grain boundary facilitates the premature initiation and propagation of the surface cracks in thin specimen. Third, the through-grain boundaries introduce by specimens machining are detrimental for rupture property. A direct comparison of rupture properties of thin-wall samples with different grain morphologies indicate that thin-wall effect can be diminished by avoiding through-grain boundary introduction.     

The effect of surface-free energy and microstructure on the condensation mechanism of water vapor

Obtaining high-water-yield drinking water in arid areas without consuming energy is still a global challenge.Since water vapor is ubiquitous, atmospheric water harvesting technologies are undoubtedly one of the most promising candidates. A typical water condensation process is analyzed in this paper(nucleation, self-growth,coalescence and sliding). The mechanisms of interactions between adsorbate and water vapor are discussed.The effect of surface-free energy and microstructure on water vapor co...     

Enhanced fatigue property by fabricating a gradient nanostructured surface layer in a reduced-activation steel

Reduced activation ferritic/martensitic (RAFM) steels have been selected as candidate structural materials for future advanced nuclear power systems. In the present work, the influence of a gradient nanograined surface layer on the fatigue properties of RAFM steels was studied. A gradient nanostructured (GNS) surface layer with a thickness of ～85 ?μm was prepared on RAFM steel utilizing surface mechanical rolling treatment (SMRT). The mean grain size was approximate 43 ?nm at the topmost surface and increased gradually with depth. The results of the stress-controlled tension-compression fatigue experiments showed that the fatigue life enhanced approximately 6 times in the SMRT samples compared to the corresponding base metal counterparts. The relationship between the applied stress amplitude and the fatigue lifetime, and the fracture morphology showed that the surface strengthening and strain delocalization were caused by GNS, which suppressed surface crack initiation process, and hence the fatigue properties of RAFM steels improved. In addition, the deformation compatibility in GNS and coarse-grained boundaries leading to more dislocation interactions and accumulation during the cyclic process, also plays a crucial role in enhancing the fatigue properties of RAFM steel.     

Esterified cellulose nanocrystals for reinforced epoxy nanocomposites

The surface of cellulose nanocrystals (CNCs) was successfully modified with methacryloyl chloride to create esterified CNCs (M/CNCs). The modification was confirmed by Fourier Transfer Infra-Red Spectroscopy, X-ray Photoelectron Spectroscopy and Zeta potential measurement. With increased surface hydrophobicity, this modified CNC material exhibited improved compatibility with organic network. When used as a filler to be incorporated into a model epoxy resin, TEM results indicated that M/CNCs particles dispersed well in the epoxy network. It was observed that the inclusion of the M/CNCs had an impact upon the heat flow for the curing of the epoxy nanocomposite, leading to an improvement in the storage modulus when tested via dynamic mechanical analysis.