求解多组分化学相平衡的一种通用算法

基于Gibbs自由能最小原理,提出一种求解多组分化学相平衡的通用算法——混沌-蒙特卡罗混合算法。分别介绍了该算法的计算步骤和关键性能参数。多个计算实例表明,本文提出的方法可以不断拓展解的空间,避免假收敛,能以完全概率、高速并行搜索到全局最优解。     

非平衡等离子体对甲烷燃烧影响的研究

建立了CH4和空气的燃烧模型,计算并分析了在气体放电产生不同量的非平衡等离子体的情况下,电离产生的主要活性粒子（O和H）和活性基（OH）对燃烧温度及燃烧室出口流场的影响。计算结果表明等离子体助燃可以明显提高燃烧温度,改善燃烧室出口的温度场和速度场,并且能够提高燃烧效率,降低污染物排放。     

Experimental study of diffusivity of hexane in bitumen-saturated porous media under high temperature/pressure conditions

Solvent mass transfer plays a key role in a thermal gravity drainage process involving solvent. The diffusion coefficients of solvent in such a process are not well studied. This article presents the effective diffusion coefficients of solvent in bitumen-saturated sands under high temperature/pressure conditions measured using a CT scanning technique. Experimental results show that the effective diffusion coefficient of n-hexane in bitumen-saturated sands varied with the solvent concentration or with the viscosity of solvent–bitumen mixture (i.e., D_e ∝ c^0.4 or D_e ∝ μ_m^−0.46). The solvent concentration weighted diffusion coefficient of n-hexane in the bitumen under the condition 160–170°C/1,900 kPa had an order of magnitude of about 10⁻⁵ cm²/s for solvent volume concentration less than 0.2. The penetration distance of n-hexane in bitumen-saturated sands depended on the nonlinearity of diffusion and had a value of −2 cm after 1-day diffusion. The stronger the nonlinearity of diffusion, the shorter the penetration distance.     

Unraveling the film-formation kinetics of interfacial polymerization via low coherence interferometry

Interfacial polymerization (IP) is one of the most important methods for fabricating thin film composite (TFC) membranes. Understanding the film-formation mechanisms is of great value for developing membranes with enhanced performance. This work proposed a novel method to in situ characterize the film-formation kinetics via low coherence interferometry (LCI). The polyamide film formed at the liquid–substrate interface was scanned in real time; the polymerization induced significant variations in the optical properties around the reaction zone. After mitigating the effects of the perturbed interface, the surface-averaged intensity profiles provide a solid basis for analyzing the film-formation kinetics at various depths. In particular, the effects of the monomer concentrations were investigated to reveal the asymmetric growth and development of irregular substructures. All the characterization results confirm that the LCI-based characterization is a powerful tool for studying the structural evolution of the IP layer and thereby providing deeper insights for optimizing TFC membranes.     

Facile synthesis of a castor oil-based hyperbranched acrylate oligomer and its application in UV-curable coatings

Fabrication and performance of the castor oil (CO)-based hyperbranched acrylate (C20AA) UV-curable coatings are highlighted in this work. Herein, C20AA was obtained through a facile reaction of a castor oil-based hyperbranched polyol (C20) with acrylic acid. FT-IR and ¹H NMR spectra confirmed the synthesis of the target C20AA. Subsequently, the as-prepared C20AA was employed for crosslinking a commercialized linear polyurethane acrylate (PUA) UV-curable oligomer. Specifically, by varying the content of C20AA over the range of 0, 20, 40, and 60 wt%, a series of UV-curable coatings were prepared and coded as C20AA-0, C20AA-20, C20AA-40, and C20AA-60, respectively, which were further cured under UV irradiation. The effect of C20AA loadings on the UV-curing efficiency and final polymer performance were investigated. Consequently, the tensile strength, Shore D hardness, pencil hardness, gel content, water resistance, and glass-transition temperature of the UV-cured coatings were greatly improved upon the addition of C20AA. Impressively, with the incorporation of 40 wt% C20AA, the resultant UV-cured coating exhibited highest double bond conversion, superior chemical resistance, and good flexibility. Additionally, all of the coatings showed outstanding transparency and good surface microstructures.     

Polytetrafluoroethylene-intercalated MXene membranes with good photothermal performance for enhanced laser ignition

Photothermal effect has been widely used in many areas such as cancer therapy, photothermal energy harvesting, and laser ignition. However, exploring reliable and efficient free-standing energy converter for enhancing the photothermal performance is still a challenge. Herein, free-standing membrane based on two-dimensional MXene (Ti₃C₂) nanosheets and polytetrafluoroethylene (PTFE) was fabricated and characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry, which demonstrated a drastic temperature rise by laser irradiation and was further used as energy converter for enhancing the photothermal performance of laser ignition. Furthermore, the initiating power of the laser initiator can be largely reduced by adding a thin layer of MXene/PTFE membrane above the B/KNO₃ cylinder. This work can give great promise for MXene-based membranes as the laser energy converter for reducing the initiating energy and promote the development of laser initiators with low initiating energy.     

In situ polymerization of flame retardant modification polyamide 6,6 with 2-carboxy ethyl (phenyl) phosphinic acid

A novel halogen-free flame retardant copolyamide 6,6 (FR-PA66) was prepared successfully by in situ polymerizing with adipic acid hexamethylene salt and 2-carboxy ethyl (phenyl) phosphinic acid (CEPPA). The elemental composition and chemical structure of FR-PA66 were characterized by energy dispersive X-ray spectroscopy, Fourier transform infrared spectrometer and ¹³C Nuclear magnetic resonance spectrometer. The flame retardancy, thermal stability, and morphology of char residues were also investigated by the limiting oxygen index (LOI), UL 94 test, thermogravimetric analysis, and scanning electron microscopy. The results showed that FR-PA66 samples had much better flame retardancy and char formation ability than pure PA66 after the flame retardant modification. The LOI values were increased from 24.0 to 28.0% by adding 6 wt % of CEPPA and all FR-PA66 samples were rated as V-0 rating in UL-94 test. Furthermore, the thermal stability analysis indicated that in situ polymerization with CEPPA effectively decreased the initial decomposition temperature and increased the amount of char residue. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48687.     

Cu-SiC磨具制备及其性能表征

笔者描述了铜-碳化硅磨具的制备过程,采用热压成形法制备了Cu-SiC磨具。该磨具主要由铜粉、酚醛环氧树脂和碳化硅磨料组成。研究了树脂、碳化硅与辅助磨料的种类、组成对磨具性能的影响。结果表明:当加入适量铜粉,复合材料磨损率会下降、耐磨性能会提高,被磨削表面不易出现凹痕、孔洞;但是铜粉添加过量时,磨具磨损率会增加。较佳配方组成为:35wt%树脂、45wt%碳化硅、15.56wt%铜粉、4.44wt%白刚玉。     

低温甲醇洗系统贫富甲醇换热器泄漏原因分析及处理

介绍了晋煤天溪煤制油分公司低温甲醇洗系统贫富甲醇换热器的泄漏情况。分析了贫富甲醇换热器泄漏初期生产运行指标的异常现象和造成泄漏的原因,认为泄漏是不同物质对设备的腐蚀、冲刷造成的,并针对泄漏的具体情况,提出了不同的检修处理措施:管束泄漏量低于10%时,可采用焊接锲形堵头将泄漏列管两端进行封堵;管束泄漏量高于10%时,如换热器设计余量足,可将封头内部隔板取出,短接进出口;将换热管材质由10#钢换为06Cr19Ni10不锈钢。