PROPELLANTS EXPLOSIVES PYROTECHNICS
·
2018
·Vol. 43
·期 6
·595-601
·
IF 1.749
Yuangang Xu,Zhongqin Zhu,Cheng Shen,Qiuhan Lin,Ming Lu
A new family of 3,9-diamino-6,7-dihydro-5 H -bis([1,2,4]triazolo)[4,3- e : 3′,4′- g ][1,2,4,5]tetrazepine-2,10-diium salts was explored as fused tricyclic triazole based energetic materials. These salts and their fused cations were constructed by in situ synthesis with 4,4′,5,5′-tetraamino-3,3′-bi-1,2,4-triazole as the raw material. All of the new compounds were fully characterized by elemental analysis, IR spectroscopy, 1 H, 13 C, and (in some cases) 15 N NMR spectroscopy, and thermal analysis. The structures of five salts were confirmed by single-crystal X-ray analysis. Computational studies associated with heats of formation and detonation properties were performed by using Gaussian 09 and EXPLO5 v6.01 programs, respectively. The desired fused tricyclic energetic salts (especially for 4 and 5 , d : 1.85-1.92 g cm −3 ; D : 8622–8942 m s −1 ; P : 34.61-37.38 GPa) display interesting thermal behaviour and are predicted to be high-performance energetic materials.
研究领域:
化学
·
材料科学
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DOI
高影响因子
ADVANCED ENGINEERING MATERIALS
·
2019
·Vol. 21
·期 8
·1900176
·
IF 2.906
Tao Yan,Hui Ren,Yaru Li,Huixin Wang,Qingjie Jiao
Porous nano-aluminum@polymer microspheres with a narrow size range are fabricated to exploit the energy advantages of nano-aluminum (nAl). Nitrocellulose (NC) and glycidyl azide polymer (GAP) act as functional binders and adhere tightly to the surface of nAl particles and aggregate them into spheres. The formed holes on the microsphere surface are considered gas diffusion channels to the microsphere interior. Confined combustion results show that nAl@GAP microspheres generate the highest peak pressure, and maximum pressurization rate of nAl@NC microspheres is comparatively higher than that of others. Given the microsphere structure, thermal behavior in air shows that the oxidation-reaction mechanism of the microspheres is close to that of nAl particles. Interfacial reactions between nAl particles and gases produced by polymer decomposition enhance microsphere reactivity. The heat released by polymer decomposition maintains the structure, activates nAl particles, and accelerates combustion propagation, which are positively correlated with the energy content of the polymer. The unconfined test results showed that nAl@GAP microsphere combustion propagates faster than that of nAl@NC microspheres.
研究领域:
材料科学
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能源工程
✓ 已验证
产品关联
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2017
·
IF 3.386
Xue Dong,Rong-Tao Duan,Yan-Peng Ni,Zhi-Jie Cao,Li Chen,Yu-Zhong Wang
Retro-Diels-Alder reaction (rDA) has been widely used as a common modification approach for expanding functional applications of polymers. Especially, it has become an effective method of current cross-linking chemistry . With the goal of designing a cross-linkable PET-based copolyester toward flame retardancy and anti-dripping during combustion, dimethyl 5-(1,3-dioxo-3a,4,7,7a-tetrahydro-1 H -4,7-methanoisoindol-2(3 H )-yl) isophthalate (DMTMI) was incorporated as the functional co-monomer into PET chains via random transesterification polycondensation . Thermogravimetry-differential scanning calorimetry (TG-DSC) and rheological studies demonstrated the existence of cross-linking behavior at high temperature. By controlling the co-monomer content, expected flame retardancy was obtained, as illustrated by the results from the limiting oxygen index (LOI) and cone calorimetry. Furthermore, LOI values increased firstly and then decreased with the content of DMTMI increased, which was related to the existence of rDA reaction, and further proposed that a competitive relationship between the release of inflammable cyclopentadiene during rDA reaction and cross-linking behavior occurred in combustion. The hypothesis was verified through pyrolysis-gas chromatograph-mass spectrometry (Py-GC-MS).
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2022
·
IF 5.767
Wanjun Zhao,Qingjie Jiao,Pengwan Chen,Shi Yan,Yanli Zhu,Bi Zhang,Xin Zeng,Dazhi Liu,Yapeng Ou,Fang Wang
Zn has been incorporated into Mg via centrifugal atomization in this work. The prepared Mg-Zn alloys have been characterized via SEM/EDS and XRD . The thermal behavior and combustion of Mg-Zn alloys have been tested by TG/DSC and laser ignition. Then, Mg-Zn alloys have been applied in pyrotechnics with PTFE as the oxidizer , followed by measuring the reactivity and ignition delay . Mg-5%Zn and Mg-10%Zn alloys consisting of α-Mg and eutectic phase (α-Mg and MgZn 2 ) in a high degree of sphericity with evenly distributed Zn were obtained. Thermal behavior characterization indicates that the oxidation of Mg-Zn alloys initiates ∼50 °C earlier than Mg along with a higher oxidation rate, which could be attributed to the lower melting point of MgZn 2 and Zn. In addition, the oxidation rate of Mg-Zn alloys is also higher than Mg that is the result of significantly lower apparent activation energy of Mg-Zn alloys than Mg. Due to the great discrepancy of melting and evaporation point between Mg, MgZn 2 , and Zn, a visible microexplosion phenomenon has been observed during the combustion process of Mg-Zn alloys. Then, Mg-Zn alloys have been applied as the fuel to replace Mg in Mg/PTFE pyrotechnics. The ignition delay of Mg-Zn/PTEE composites is shorter than that of Mg/PTFE, which is due to the easier oxidization initiation of Mg-Zn alloys compared to Mg. Besides, the lower melting and evaporation points of MgZn 2 and Zn than Mg can accelerate the combustion of Mg-Zn alloys, leading to the improved peak pressure and reaction rate of Mg-Zn/PTEE. Thus, the lower apparent activation energy of Mg-Zn alloys and the lower melting point of MgZn 2 and Zn could promote the energetic kinetics of Mg-Zn alloys synergistically. Above all, the prepared Mg-Zn alloys in this study are ambitious candidates in pyrotechnics for controllable ignition and reactivity kinetics.
研究领域:
材料科学
·
燃烧学
·
烟火技术
✓ 已验证
产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2019
·
IF 3.078
Peng Wei,Yanping Wang,Yumin Xia,Yong He,Yimin Wang
Firstly, PEGn-TA monomers with carboxyl functional groups were synthesised by terephthalic acid (TA) and poly(ethylene glycol) (PEG) with molecular weight of 200, 400 and 600. Then, photocrosslinkable thermotropic liquid crystal copolyesters derived from PEGn-TA, 4,4ʹ-biphenol, 4-hydroxy-cinnamic acid and 4-hydroxy-benzoic acid were successfully obtained by Vilsmeier adduct solution polymerisation method. Influence of PEG molecular weight on thermal behaviour, liquid crystal mesophase, hydrophilicity, structure and photoactivity were investigated by various measurements. Experimental results indicated that all copolyesters showed nematic mesophase textures, relative low melting temperatures, and two glass transitions as well as better hydrophilicity were observed for those contained higher PEG molecular weight. Photocrosslinking rate was increased first and then decreased due to effect of flexible PEG moieties. The resulted copolyesters with liquid crystal behaviour, excellent hydrophilicity and photoactivity could be potentially used as biomaterial.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2021
·
IF 7.514
You Tian,Da-Wen Sun,Zhiwei Zhu
Nature-inspired natural deep eutectic solvents (NADESs) as anti-freezing agents including Pro:Glc (5:3), Pro:Glc (1:1), Pro:Sor (1:1), and Urea:Glc:CaCl 2 (3:6:1) were prepared. Viscosity ( η ), conductivity ( σ ), activation energy of viscous flow ( E η ) and conduction ( E ᴧ ), transverse relaxation time (T 2 ), thermal behaviours, and anti-freezing capacities of the NADESs were investigated. A critical T 2 of 24.60 ms for η changes was obtained, and the relationship between η and T 2 was determined as ln η = -1.398lnT 2 + 10.688. Differential scanning calorimetry and low-field nuclear magnetic resonance analyses indicated NADESs could hinder the molecular motion as temperature decreased through enhancing the hydrogen-bonding strength, endowing them with excellent anti-freezing capacity. NADESs showed varied E η (41.58 ∼ 45.72 kJ mol −1 ) and E ᴧ (48.31 ∼ 63.08 kJ mol −1 ), of which Pro:Sor (1:1) possessed the greatest ones, showing its greatest temperature sensitivity and best anti-frosting capacity. Applications in frozen chicken breast further announced the potentials of NADESs as anti-freezing agents for the industry.
研究领域:
食品科学
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化学
·
生物物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FLUID PHASE EQUILIBRIA
·
2014
·
IF 2.241
Guo-Min Yu,Li-Sheng Wang,Chao-Jun Du,Jian Sun
A phosphorous flame retardant of phosphoric acid , P , P ′-1,4-phenylene P , P , P ′, P ′-tetraphenyl ester (PAPTE) was synthesized by diphenyl chlorophosphate and hydroquinone . The structural features of PAPTE were investigated with mass spectra (MS), infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and high-performance liquid chromatograph (HPLC) methods. The thermal behavior of PAPTE was analyzed with differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) instruments. A static analytic method was used to measure the solubilities of PAPTE in the several selected pure solvents, which are methanol, ethanol, acetone, ethyl acetate , acetonitrile , methyl acetate , toluene, ether, n -propanol, i -propanol, where the temperatures range is from 288.25 to 333.45 K. The experiments were also performed in the binary mixed solvents of acetone and methanol. Several thermodynamic models were used to correlate the experimental solubility data, such as Wilson, nonrandom two-liquid (NRTL), UNIQUAC equations. The solubility data of PAPTE in binary solvents were correlated with the modified Wilson model. The calculated results showed that those models can excellently reproduce the experimental data and the UNIQUAC equation reveals the better ability in correlation. Using the Scatchard–Hildebrand methodology, the activity coefficients, solubility parameter of the solute and the partial molar excess enthalpies at infinite dilution were calculated.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
CARBON
·
2018
·
IF 7.082
Baisong Guo,Biao Chen,Xinming Zhang,Xi Cen,Xinhua Wang,Min Song,Song Ni,Jianhong Yi,Tao Shen,Yong Du
In this work, the effects of aluminum carbide (Al 4 C 3 ) on the mechanical properties and thermal behaviors of Al based composites reinforced by SiC and carbon nanotubes (CNTs) were investigated. The formation of Al 4 C 3 was precisely controlled in the temperature range from 530 °C to 630 °C (80%–95% of the Al melting point) during the post heat treatment. Microscopy observations revealed that Al 4 C 3 rods are originated from CNTs instead of SiC particles. Quantity and size of Al 4 C 3 are highly dependent on the heat treatment temperature. It was found that the mechanical properties of the Al based composites were significantly affected by the size of Al 4 C 3 . Moreover, the formation of Al 4 C 3 helps to decrease the coefficient of thermal expansion (CTE) of the composites due to the consumption of Al and the enhanced interfacial bonding . This study provides a potential approach for ameliorating the mechanical and thermal performances of CNTs reinforced metal matrix composites .
研究领域:
材料科学
·
力学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuxiang Li,Xi Chen,Lei Zhang,Ruishan Han,Iftikhar Hussain,Xiaoxia Ma,Kaili Zhang
Metastable intermolecular composites (MICs) composed by solid fuel and oxidizer can undergo violent redox reaction with release of huge amount of energy. Integration of MIC with microelectromechanical-system (MEMS) is of particular interest to meet the demand of miniaturization in modern pyrotechnic devices. Meanwhile, fluorine-containing oxidizers are favored in MIC owing to their potential to fluorinate the oxide passivation layer in common elemental fuels. Herein, Co(OH)F was employed for the first time as a novel fluorine-containing oxidizer in Al-based MIC. Vertically aligned Co(OH)F@Al nanobelt arrays (NAs) with tunable morphology were successfully fabricated on a variety of substrates (Si, glass, Ni, Cu, Ti) via a facile hydrothermal synthesis followed by electron beam evaporation. The whole fabrication process is highly compatible with modern MEMS technology. The thermal behavior of pure Co(OH)F and Co(OH)F@Al composites was comprehensively investigated by TG-DSC and a series of ex-situ and in-situ characterization. It was found that, Co(OH)F@Al composites achieved main exothermal reaction before melting of Al regardless of morphology and equivalence ratio. This feature is attributed to the etching of Al 2 O 3 shell by HF released from Co(OH)F which is termed as pre-ignition reaction. To elucidate the effect of micro-structure on the actual specific heat release, we proposed a phenomenological model which can be a reference for future micro-structure design of MIC.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Jiabo Tang,Xinghong Liu,Xiaolin Chang,Xiang Ji,Wei Zhou
Geopolymers are an economical, durable and environmentally friendly building material that achieves ultimate strength superior to concrete within hours and can withstand extreme high temperatures without degradation, but they lack elasticity and have poor flexural strength . To tackle these challenges, this paper presents a novel nanotechnological and affordable method to produce an elastic geopolymer that can be used as a construction material. Specifically, we report a simple and straightforward strategy that combines electrospinning and the sol-gel process to construct geopolymer nanofibers with superelasticity , extreme durability, and fire resistance. In order to improve the safety level of building construction sites that experience extreme conditions, such as freeze-thaw deterioration, the geopolymer nanofibers can be further functionalized by incorporating various functional components. In this study, Fe 3 O 4 nanoparticles (NPs) adsorbed by an electric double layer structure were dispersed in a geopolymer sol (SAPOs). Elastic geopolymer nanofibers embedded with Fe 3 O 4 nanoparticles were then prepared (Fe 3 O 4 /SAPOs) by an electrospinning method . Nanofibers constructed by such a compound method could have superparamagnetic behaviors and stable chemical properties. When Fe 3 O 4 /SAPOs are exposed to an alternating magnetic field , eddy currents are generated that cause the geopolymer nanofibers to heat up. This self-heating behavior is a powerful feature that enhances the freeze-thaw resistance of building materials at high altitudes. The nanotechnological route of this study could provide novel insights into the development of advanced construction materials.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2015
·Vol. 133
·期 5
·
IF 1.768
Guangfa Zhang,Qinghua Zhang,Qiongyan Wang,Xiaoli Zhan,Fengqiu Chen
A series of gradient fluorinated copolymers with a broad variation of the monomer units in the polymer chain were synthesized via semibatch CPDB-mediated RAFT miniemulsion polymerization technique. In the presence of RAFT agent 2-cyanoprop-2-yl dithiobenzoate (CPDB), the copolymerization of BMA and FMA in miniemulsion exhibited typical features of a controlled molecular weights and narrow polydispersities. The macromolecular structure and thermal behavior of the synthesized fluorinated copolymers were investigated in detail. The DSC analyses show that the gradient copolymers showed a unique thermal behavior with broad range of transition temperature. It was also confirmed that the fluorinated gradient copolymer exhibited obvious surface segregation structure and ultra-low surface energy between 16.8 and 20.3 mN/m. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 42936.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 23
·13808-13816
·
IF 3.108
Cheng-Yang Cao,Song Lu,Dan Zhang,Lun-Lun Gong,He-Ping Zhang
The 5AT/Sr(NO3)2 mixture has recently attracted attention as a gas-generating agent for use in novel fire-suppression applications. However, it cannot provide the desired combustion behavior alone. Thus, nitroguanidine (NQ) was added as a fuel component to 5AT/Sr(NO3)2 in attempt to improve the mixture's combustion behavior. The effects of NQ on the thermal and burning characteristics of 5AT/Sr(NO3)2 were investigated. Thermogravimetry-differential scanning calorimetric (TG-DSC) analysis with four heating rates (5, 10, 15, 20 K min−1) under a nitrogen atmosphere was performed to determine the thermal characteristics and non-isothermal reaction kinetic parameters. The addition of NQ decreases the activation energy of the Stage II and III decomposition reaction, and accelerates the redox reaction and decomposition of Sr(NO3)2. Thermodynamic calculations and measurements of temperature profile and liner burning rates were performed to evaluate the combustion characteristics. Adding NQ decreased the adiabatic combustion temperature, outlet temperature, average flame height, flame oscillation frequency and pressure exponent of Vieille's equation, and increased the gas output and linear burning rate. Notably, mesa burning occurred when NQ was added, the mechanism of which is elaborated using a physical combustion model. The analysis deepens the understanding of when the gas-phase or condensed-phase reactions control the burning characteristics of the composite propellant.
研究领域:
材料科学
·
燃烧学
·
推进剂研究
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）