Effective Fixation of Carbon in g‐C3N4 Enabled by Mg‐Induced Selective Reconstruction

The methodology of metal‐involved preparation for carbon materials is favored by researchers and has attracted tremendous attention. Decoupling this process and the underlying mechanism in detail are highly required. Herein, the intrinsic mechanism of carbon fixation in graphitic carbon nitride (g‐C₃N₄) via the magnesium‐involved carbonization process is reported and clarified. Magnesium can induce the displacement reaction with the small carbon nitride molecule generated by the pyrolysis of g‐C₃N₄, thus efficiently fixing the carbon onto the in situ template of Mg₃N₂ product to avoid the direct volatilization. As a result, the N‐doped carbon nanosheet frameworks with interconnected porous structure and suitable N content are constructed by reconstruction of carbon and nitrogen species, which exhibit a comparable photoelectric conversion efficiency (8.59%) and electrocatalytic performances to that of Pt (8.40%) for dye‐sensitized solar cells.     

Synthesis and modification of trifunctional epoxy resin with amine terminated polydimethyl siloxanes for semiconductor encapsulation application

Epoxy resins based on the triglycidyl ether of tris(hydroxyphenyl)methane (TETM) possess a very high heat distortion temperature and superior thermal oxidative stability over other types of epoxy resins. The high performance trifunctional epoxy resin (TETM) was synthesized by the condensation of a hydroxybenzaldehyde with phenol followed by epoxidation with a halohydrin. The structure of the synthesized TETM was confirmed by infrared (IR), mass spectra (MS), and nuclear magnetic resonance (NMR) spectroscopy. Amine terminated polydimethylsiloxanes (ATPDMS) were used to reduce the stress of trifunctional epoxy resin cured with phenolic novolac resin for electronic encapsulation applications. The dispersed silicone rubbers effectively reduce the stress of cured epoxy resins by reducing the coefficient of thermal expansion (CTE) and flexural modulus, while the glass transition temperature (T_g) is depressed by only a small amount.     

Compact tri‐notched ultrawideband bandpass filter design using CSRR,DGS, and FMRR configurations

The folded multiple‐mode resonators with complementary split ring resonator (CSRR), and defected ground structures (DGS) are introduced for notched ultrawideband (UWB) bandpass filter (BPF) design in this article. Using the CSRR, FMRR, notched wide‐band BPF, a notch response can exist in the UWB passband for blocking the interference. Adjusting the size factor of CSRR, the wide tuning ranges of notch frequencies included the desired frequencies of 5.2/5.8 GHz are achieved. The lower insertion loss (0.31 dB), higher rejection level (?48.40 dB), wider bandwidth (FBW 75%), and wider stopband (extended to 2.01 f₀ below ?20 dB rejection level) of UWB band at the central frequency f₀ = 4.58 GHz are obtained. Second, design a CSRR, DGS, FMRR, tri‐notched UWB filter, the wider bandwidth (3.1–9.8 GHz) with FBW = 126%, lower insertion loss (0.26 dB), and higher rejection level (?44 dB) of UWB band at central frequency f₀ = 5.6 GHz are presented. Using the CSRR and interdigital couple, three notch responses can exist in the UWB passband for blocking the interference signals. Adjusting the size factor of CSRR and interdigital couple, the wide tuning ranges of notch frequencies included the desired frequencies of 5.18/6.10/8.08 GHz are achieved. The wide tuning ranges of three notched frequencies cover from 5.0 to 8.4 GHz. It is a simple way to control the notch responses. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:571–579, 2014.     

1,2,3-三羧甲氧基苯的催化合成及其与钍的显色反应

以三丁基乙基硫酸乙酯铵为相转移催化剂 ,用焦性没食子酸、一氯乙酸和氢氧化钠为原料 ,合成了一种新的钍分析试剂——— 1,2 ,3-三羧甲氧基苯 (TCMOB)。显色试验表明 ,TCMOB是一种性能优良的钍显色剂 ,在 2 5ml 4mol/L的HClO4 介质中形成 1∶1的配合物 ,其最大吸收峰位于 32 5nm ,吸光系数为ε4 2 5nm =8.86× 10 4 L·mol- 1·cm- 1,钍的含量在 0～30 μg/ 2 5ml范围内符合比尔定律     

Tri‐ammonium end functional polyethylene: facile synthesis and application as an intercalation agent

Organo‐modification of montmorillonite (MMT) is crucial for the promotion of a fine dispersion of MMT into an (often hydrophobic) polymer matrix. Ammonium‐terminated polymers are more efficient in modifying clay compared to small organic cations such as alkyl ammoniums or side functionalized polymers. Herein, tri‐amino end functional polyethylene (PE‐3 N) with low molecular weight was first synthesized via an efficient and robust epoxide ring‐opening reaction by treating epoxide‐terminated PE with diethylenetriamine. The chemical structure of PE‐3 N was unambitiously characterized by chromatographic and spectral methods. By reacting with excess HCl, PE‐3 N was subsequently converted to tri‐ammonium end functional polyethylene (PE‐3 N⁺), which serves as an intercalation agent of MMT. By adjusting the weight ratio of PE‐3 N⁺ to pristine MMT (R_P/M) applied in the static melt intercalation process, correlations between the extent of exfoliation and R_P/M were successfully established. XRD results revealed that complete exfoliation of MMT could be afforded with R_P/M as low as 1, which is the lowest value ever reported for ammonium‐terminated polymers applied as intercalation agents. SEM micrographs showed that MMT sheets were swollen by PE‐3 N⁺, affirming the successful modification of MMT. The PE modified MMT obtained may find application in preparing high‐performance PE/MMT nanocomposites. © 2017 Society of Chemical Industry     

磷酸三间甲苯酯的碱法合成

与传统的合成方法相比,间甲酚与三氯氧磷碱法合成磷酸三间甲苯酯具有反应时间短、温度低、腐蚀性小和常压下即可进行等优点。以该反应收率为目标,研究了反应物料与有机溶剂的配比、反应温度和碱液浓度等因素的影响。在适宜的反应条件下,磷酸三间甲苯酯的收率可达到93％。目前,以实验数据为依据的该碱法工艺已实现工业化生产。     

Glycerol ethers synthesis from glycerol etherification with tert-butyl alcohol in reactive distillation

This paper presents a study of glycerol etherification with tert-butyl alcohol catalyzed by Amberlyst 15 in reactive distillation (RD). A thermodynamic analysis is firstly investigated by applying three group contribution methods, to determine the equilibrium composition by minimization of the Gibbs free energy and to compare the predicted values against measured data. Next, the kinetic model parameters are regressed by matching measured data from an autoclave reactor. The activity based Langmuir-Hinshelwood model is found to give the best representation of the reaction rate data. The regressed kinetic rate expressions are also compared against independently measured data in fixed bed reactors reported in the literature and found to give a good match. Finally, using the developed models, it is shown by simulation as well as verification by experiments, that the suitable RD configuration for the production of glycerol ethers in RD is the one consisting of 6 rectifying stages and 6 reaction stages without stripping stage.     

Reverse Micelle Mediated Bulk Liquid Membrane Separation of Platinum Gold and Silver From Real Samples

Simple and selective reverse micelle mediated bulk liquid membrane extraction procedure is developed for the separation and simultaneous pre-concentration of precious metals from valuable wastes like spent auto mobile catalytic converters and gold jewelry washings. Quantification has been carried out using inductively coupled plasma optical emission spectrometry (ICP-OES). Tri octyl methyl ammonium chloride (TOAC), a cationic hydrophobic surfactant, forms reverse micelles after dissolution in trichloroethylene facilitating the extraction of platinum, gold and silver ions into the bulk liquid membrane. The procedure is based on the formation of extractable hydrophobic ion-associates between TOAC cationic reverse micelles and anionic metal ions. These hydrophobic ion-associates which are transported into the bulk organic membrane from an aqueous feed phase are subsequently stripped into a receiving solution in a unitary process. Optimum conditions for the overall transport efficiency of precious metals have been evaluated. The accuracy of the procedure was validated by analyzing GBWAu-18 ore from faulted zone and PTM-1a nickel-copper sulphide matte certified reference materials. The procedure has been applied to spent catalytic converters and jewellery washings.

Supplemental materials are available for this article. Go to the publisher's online edition of Separation Science & Technology to view the supplemental file.     

沥青混合料三轴剪切试验的离散元模拟研究

为了更好地评价和预估沥青混合料抗车辙能力,基于离散元方法,应用PFC2D软件对沥青混合料的三轴剪切试验进行离散元数值模拟,并将模拟结果与实验室试验结果进行了对比分析.结果表明,离散元模拟结果与实验室试验结果具有较好的相关性,且规律一致,验证了模型的正确性;可基于此模型建立评价和预估沥青混合料抗车辙能力的虚拟试验方法.     

Effect of prepolyurethane on the performances of poly(acrylates‐co‐urethane) copolymer

Poly(acrylates‐co‐urethane) copolymers were synthesized by the polymerization of acrylates and 2‐hydroxyethyl acrylate terminated polyurethane (prepolyurethane) at room temperature. The polymerization was initiated by the radicals, which were produced by the oxidation of tri‐n‐butylborane (TBB) from the mixing of TBB/hexamethylene diamine complex and diisocyanate decomplexer. The effects of prepolyurethane on the performances of copolymers were discussed. The results indicated that the damping property and flexibility of copolymers were obviously higher than that of pure polyacrylates. Dynamic mechanical analysis and transmission electron microscope results showed that PU was dispersed in polyacrylates phase very well. The copolymers were found to bond well to low surface energy materials because of introduction of PU. The lap shearing strength of copolymer bonding polypropylene or polyethylene both had the trend of first increase followed by decrease with the prepolyurethane content increase. The copolymers as adhesives were also shown to have a long working life and be suitable for utilization at low temperature especially at room temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010