Energetic Materials Frontiers
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2021
·
IF 0
Yang Liu,Yang Guo,Li-han Fei,Zhao-ming Mai,Cheng-long Tang,Zhi Wang,Ying-tao Wu,Zuo-hua Huang
Ionic liquids have a wide engineering application foresight due to their easy and safe storage and handling while are limited by the unclear mechanism of hypergolic ignition. In this study, three dicyanamide-based ionic liquids with different cations, 1-allyl-3-methyl imidazolium ([AMIm]), 1-ethyl-3-methylimidazolium ([EMIm]) and 1-butyl-3-methyl-imidazolium ([BMIm]), are prepared to react with white fuming nitric acid through drop tests. The diameter of ionic droplet is 2.2 mm, the impact velocities are controlled at 0.16/0.45/0.62/0.82/1.01 m s -1 by adjusting the dropping height, and the whole reacting process is recorded by three cameras to provide macroscopic, microscopic and infrared details. The promotion effect of impact velocity on hypergolic ignition probability is confirmed for all the ionic liquids, and the minimum impact velocity for successful hypergolic ignition of each ionic liquid was determined. The temperature evolution of hypergolic process shows a non-monotonic trend, and a four-stage process was performed to reveal the hypergolic mechanism. The experimental results indicate that short-chain alkyl and unsaturated substituents in cations are favored for hypergolic ignition, and the datasets are conducive for kinetic model construction.
研究领域:
化学工程
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燃料科学
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DOI
JOURNAL OF APPLIED POLYMER SCIENCE
·
2016
·Vol. 134
·期 8
·
IF 1.866
Defa Hou,Hanbing Ma,Xiuyun Li,Jie He,Huiwei Liao
A novel easily curing system of 2,2- bis (4-cyanatophenyl) propane(BACY) was prepared by employing 4,4′-(Hexafluoroisopropylidene) Diphenol (BPAF) as modifier. The curing efficiency of BPAF was evaluated by means of differential scanning calorimetry (DSC) and Fourier translation infrared spectroscopy analysis (FTIR). It was found that the exothermic peak temperature ( T p ) was 168 °C when the content of BPAF/BACY was 15/85 by weight, while the temperature of BACY was 215 °C under the same conditions when trace of cobalt(III) acetylacetonate(CoAt(III)) was added. Besides, BPAF/BACY system owned outstanding properties including excellent curing characteristics, high shear strength, remarkable dielectric properties and high thermal stability in contrast to BACY, 4,4′-(1-methylethylidene) bisphenol(BPA)/BACY, and nonylphenol(NoP)/BACY systems. Moreover, the properties of cured BPAF/BACY modified by different proportions of BPAF were studied in detail. It was shown that moderate BPAF was conducive to most properties of polycyanurate, and the optimal proportion of BPAF/BACY was 15/85 by weight. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44518.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
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2020
·Vol. 56
·期 1
·870-885
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IF 3.553
Jia Daikun,Yang Jianxiao,He Jiyu,Li Xiangmei,Yang Rongjie
Abstract The rapid depletion of energy resources is the most serious challenge facing humanity today. Energy consumption by buildings is the largest component of energy consumption, and most of it is in the form of heat loss. Therefore, many buildings use rigid polyurethane foam (PUF) as thermal insulation material to effectively reduce heat loss. However, the greatest disadvantage of PUF is its high flammability. In this work, to reduce the risk of fire caused by PUF, melamine-based polyol containing phosphonate and alkynyl groups (MF 3.5 and MB 3 F 3 ) is synthesized and used to improve the flame retardancy of PUF by replacing common polyether polyol. The effects of MF 3.5 and MB 3 F 3 on the physical and mechanical properties, cell morphology, thermal stability and flame retardancy of PUF are systematically studied. The research results show that the flame-retardant polyols have no effect on the thermal insulation properties of PUF, but result in a slight decrease in compressive strength. Thermogravimetric analysis proves that MF 3.5 and MB 3 F 3 can increase the temperature of the maximum mass loss rate and reduce the maximum mass loss rate, and significantly increase the char yield at 800 °C. The limiting oxygen index (LOI) value is increased to 24.3%. Cone calorimetry experiments show that MB 3 F 3 reduces the peak heat release rate and total heat release by 28.2% and 30.5%, respectively. Vertical combustion tests show that the average burning rate of the flame-retardant PUF is much slower, and melt-dripping behavior is eliminated. The flame retardancy of PUF is improved mainly through a condensed phase mechanism. Graphic abstract
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2014
·
IF 2.235
Jing-Xiu Hu,Hao Shang,Jin-Gui Wang,Liang Luo,Qiang Xiao,Yi-Jun Zhong,Wei-Dong Zhu
Melamine based microporous organic polymers (MBMOPs) have been prepared via a one-pot polymerization using the Schiff base reaction. Various techniques such as FT-IR, Ar adsorption, SEM, TEM, and TG have been used to characterize the textural structure, porosity, and stability of the synthesized MBMOPs. The adsorption isotherms of CO2 and N2 on MBMOPs have been accurately measured at pressures up to 118 kPa and different temperatures. Ascribed to the specific affinity of amine groups for CO2, the robust microporous MBMOPs display excellent CO2 adsorption performance in terms of both capacity, up to 2.8 mmol g–1 at 273 K and 118 kPa, and selectivity over N2. Dual-site Langmuir (DSL) or single-site Langmuir (SSL) model describes well the equilibrium data for the adsorption of CO2 or N2 on MBMOPs, respectively. The binary gas adsorption isotherms predicted by the ideal adsorbed solution theory (IAST) show that the prepared MBMOPs exhibit very high selectivities for CO2 over N2, up to 83.7, for equimolar mixtures of CO2 and N2 at 298 K and 100 kPa. The dynamic CO2 adsorption capacity and selectivity against N2 over MBMOPs have been experimentally investigated by breakthrough column technique at 1 bar and 298 K, indicating that a complete separation is available. Remarkably, CO2 capture–regeneration experiments indicate that MBMOPs can be easily regenerated by only purging with He or N2 rather than by raising the temperature, suggesting that MBMOPs are promising candidates of pressure swing adsorption (PSA) adsorbents for the separation of CO2–N2.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2020
·Vol. 16
·期 37
·2003162
·
IF 11.459
Chongbei Wu,Guanhang Yu,Yue Yin,Yuze Wang,Li Chen,Qing Han,Junwang Tang,Bo Wang
Conjugated polymers are promising light harvesters for water reduction/oxidation due to their simple synthesis and adjustable bandgap. Herein, both cyanamide and triazole functional groups are first incorporated into a heptazine-based carbon nitride (CN) polymer, resulting in a mesoporous conjugated cyanamide-triazole-heptazine polymer (CTHP) with different compositions by increasing the quantity of cyanamide/triazole units in the CN backbone. Varying the compositions of CTHP modulates its electronic structures, mesoporous morphologies, and redox energies, resulting in a significantly improved photocatalytic performance for both H 2 and O 2 evolution under visible light irradiation. A remarkable H 2 evolution rate of 12723 µmol h −1 g −1 is observed, resulting in a high apparent quantum yield of 11.97% at 400 nm. In parallel, the optimized photocatalyst also exhibits an O 2 evolution rate of 221 µmol h −1 g −1 , 9.6 times higher than the CN counterpart, with the value being the highest among the reported CN-based bifunctional photocatalysts. This work provides an efficient molecular engineering approach for the rational design of functional polymeric photocatalysts.
研究领域:
材料科学
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化学工程
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能源科学
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2023
·
IF 15.1
Yi Liu,Shuangjiang Li,Ying Chen,Mengrui Li,Zewen Chen,Tianding Hu,Lan Shi,Manoj Pudukudy,Shaoyun Shan,Yunfei Zhi
The development of highly efficient and metal- and halogen-free heterogeneous catalysts for the chemical conversion of CO 2 to cyclic carbonates plays a critical role in the reduction of greenhouse gas emissions. Herein, two melamine-based organic polymers namely UM-OP and AM-OP with abundant N sites and –NH- groups were synthesized by a facile method and their activity for cycloaddition of CO 2 with epoxides was investigated. The structural analysis shows that the UM-OP and AM-OP catalysts were composed of specially designed urea and amide group linkages, respectively. UM-OP and AM-OP are metal-free, halogen-free, and can efficiently catalyze CO 2 cycloaddition under solvent-free and cocatalyst-free conditions. Moreover, the UM-OP catalyst exhibited higher catalytic activity than AM-OP, good structural stability, recyclability, separability from the products, and shown high activity to a series of epoxides. The density functional theory (DFT) calculations revealed the activation of epoxides by –NH- groups and CO 2 by N sites in the samples, respectively, and N sites can also act as nucleophiles to realize ring opening of epoxides. Combining the results of experiments and calculations, it was further found that the double –NH- (urea group) is more efficient than single –NH- (amide group) to activate the epoxides. This paper reveals the mechanism of N sites and –NH- groups synergistically catalyzing the CO 2 cycloaddition, and further supports the theory that N atoms acts as nucleophile for ring opening, providing a reference for the design of metal- and halogen-free heterogeneous catalysts.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2022
·Vol. 9
·期 17
·4320-4328
·
IF 7.779
Jinyu Zhu,Guoqiang Zhang,Yangsen Xu,Wei Huang,Chuanxin He,Peixin Zhang,Hongwei Mi
Carbon nitride materials have achieved great accomplishments in solar-to-hydrogen energy conversion under visible light. However, the weak kinetics and rapid recombination of the photogenerated charge carriers result in low photocatalytic efficiency, which hinders its practical utilization. Herein, terminal cyanamide groups were grafted on K+-inserted crystalline carbon nitride (KCCN-cya) via a potassium-salt (KSCN and KOCN)-assisted one-step crystallization process. The cyanamide groups, which have high electron accepting ability, contribute to the formation of a built-in electric field (BIEF). The enhanced charge separation and dislocation was verified through linear sweep voltammetry (LSV) and electron paramagnetic resonance (EPR). Kelvin probe force microscopy (KPFM) measurements revealed the increased fluctuations of localized potential, which induced the formation of a BIEF in KCCN-cya. Moreover, the HOMO and LUMO distribution obtained for KCCN-cya using DFT computations was more highly separated than that of KCCN materials, indicating the dislocation of generated electron–hole pairs and the effective BIEF construction after the implantation of electron-withdrawing cyano terminals. As a result, the constructed BIEF promoted the separation of photogenerated electrons and holes in KCCN-cya samples, which thus exhibited an approximately three-fold improvement in hydrogen evolution activity under visible light. This finding demonstrated that introducing an electron-withdrawing group (i.e., –CN) into an organic photocatalyst would be a promising way to improve photocatalytic activity and solar energy conversion.
研究领域:
材料科学
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光催化
·
太阳能转换
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICA CHIMICA ACTA
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2019
·
IF 5.256
Huan Liu,Yue Hua,Yuanyuan Cai,Luping Feng,Shuai Li,Hua Wang
A nanocomposite nanozyme has been fabricated through mineralizing gold-silver bimetals into Hemin (Hem)-coupled melamine (MA) polymer matrix for visual colorimetric analysis of H 2 O 2 and glucose. Catalytic Hem was cross-linked onto MA scaffold for the mineralization of Au–Ag bimetals yielding the rod-like nanocomposite of MA-Hem/Au–Ag. It was discovered that the resulting nanocomposite could present high aqueous stability and especially improved catalysis, which was more than four-fold higher than that of native Hem. Catalytic kinetics studies indicate that the prepared nanocomposite nanozyme could present much higher affinities to the substrates than those of native Hem or even horseradish peroxidase . Herein, the so mineralized Au–Ag bimetals with the “silver effect” would act as “nanowires” for promoting the electron transferring of nanocomposite nanozyme. Moreover, the Hem-coupled MA polymer matrix with high specific surface area could ensure the high adsorption capacity for the reactant substrates and targeting analytes. The application feasibility of the developed nanocomposite nanozyme was demonstrated subsequently by the colorimetric assays for H 2 O 2 and glucose separately in milk and blood samples, with the linear ranges of 0.010–2.50 mM and 0.0050–2.0 mM, respectively. Such a bimetal mineralization-based fabrication route may open a new door toward the design of diverse nanocomposites nanozymes with improved catalysis and adsorption performances.
研究领域:
材料科学
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分析化学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2022
·
IF 9.965
Feng Chu,Yezi Hu,Kaiyue Zhang,Xiangjun Li,Guixia Zhao,Xiubing Huang,Ge Wang
Conjugated polymers have a broad application foreground in the field of photocatalytic organic synthesis to produce value-added chemicals due to their functional diversity, broad light responsive ability, high thermal and chemical stability, and tunable band structure . Herein, using mixed chloride salts (i.e., NaCl/LiCl) as building template, a series of porous conjugated polymers constructed by melamine and terephthalaldehyde monomers were obtained through a Schiff-base reaction in the absence of any external solvent. Melamine-terephthalaldehyde polymer (i.e., PMTPA-x, x represents the mass ratio of salt-mixture to mixed precursors of PMTPA) materials displayed porous morphologies and possessed different energy band structures via regulating the mass ratio of mixed-salt to monomers. Specifically, PMTPA-20 has a larger specific surface area and more suitable redox potential towards the photocatalytic oxidative coupling of amines to imines . Under visible light , with molecular oxygen as oxidant, PMTPA-20 achieves 97% conversion of benzylamine in 8 h which is 3.9 times higher than that of pristine PMTPA (25% conversion in 8 h). In addition, PMTPA-20 catalyst has good structure stability and reusability performance for photocatalytic reactions.
研究领域:
材料科学
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化学工程
·
光化学
·
有机合成
·
催化
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）