POLYMER DEGRADATION AND STABILITY
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2020
·
IF 4.032
Yaoyuan Xu,Jun Long,Runze Zhang,Yunzhe Du,Shengjie Guan,Yuying Wang,Lingyun Huang,Hongwei Wei,Li Liu,Yudong Huang
Silicone resins, due to its excellent high thermal stability, are widely applied in high-temperature environment. However, it is still a problem that the initial decomposition temperature of silicone resins is relatively low, which limits their wider applications. In this paper, three kinds of polyhedral oligomeric silsesquioxane (POSS) (aminopropyl, mercaptopropyl and chloropropyl) were synthesized and analyzed by FTIR, NMR and MS for structure characterization and purity analysis. Significant improvement of thermal stability was achieved by incorporating POSS into silicone resins. Three different POSS were used to modify silicone resins, and the effects of different POSS on thermal stability of silicone resins were studied. The results indicated that the thermal stability of octa-aminopropyl POSS modified silicone resins improved most significantly, with the decomposition temperature increased by nearly 45 °C compared with pure silicone resins. Moreover, the thermal decomposition mechanism of silicone resins with different POSS was studied, and chemical simulation indicated the thermal stability of silicone resins greatly improved by forming hydrogen bond between POSS and silicone resins. And the results showed one distinctive mode of increasing thermal stability, forming hydrogen bond to block resin chains' movements.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
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2019
·Vol. 139
·期 2
·999-1006
·
IF 2.471
Xie Xing-Hua,Feng Yu-Qing,Liu Shang-Hao,Zhu Jing
Emulsion explosives (EE) are one of a typical industrial explosive that is widely used in engineering and mining applications due to its high detonation performance and ideal safety characteristics. However, since an EE is a multicomponent mixture with an oil-in-water structure, the presence of some substances or impurities can reduce the safety of the EE and cause accidents. We investigated the influence of ferrous ion on the thermal behavior and stability of EE during production and storage. The thermogravimetry–differential scanning calorimetry and water solubility method were selected for the assessment of thermal behavior and stability of the EE. According to kinetic parameters, the apparent activation energy ( E a ) of the EE and the EE with ferrous ion additives was determined. The results indicated that ferrous ion could decrease the thermal decomposition temperature and E a of EE. Moreover, the degree of crystallization of ammonium nitrate increases as storage time and ferrous ion content increases. It is of important significance to reduce the hazards of the EE and to improve both safety and stability during production and storage.
研究领域:
化学工程
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安全科学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
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2017
·Vol. 35
·期 12
·1463-1473
·
IF 1.692
Yang Zhen,Li Ning,Yang Xiao-xue,Zhang Xiao-a,Jiang Sheng-ling,Lyu Ya-fei
o -Carborane-containing poly(hydroxy ethers) ( P1 , P2 and P3 ) were synthesized via “advancement reaction” of o -carborane-containing bisphenol ( 4 ) and diglycidyl ether of bisphenols (DGEBA and 1 ). FTIR and 1 H-, 13 C-, and 11 B-NMR were utilized to characterize the obtained polymers. TGA test was conducted under nitrogen and air. It is found that the shielding effect of carborane moiety on its adjacent aromatic structures contributes to high initial decomposition temperatures, while oxygen in air has an adverse effect on the initial decomposition temperature. The oxygen can combine with polymer chain to form peroxide and hydroperoxide groups, which are more reactive during the degradation process. Besides, o -carborane-containing poly(hydroxy ethers) have high char yield at elevated temperatures. The boron atom combines with oxygen from the polymer structure or/and from air, thus to form a three-dimensional network linked with B—O—B and B—C bonds, and retain the polymer weight to a large extent.
研究领域:
材料科学
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高分子化学
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产品关联
DOI
高影响因子
Nanoscale
·
2024
·
IF 5.8
Xiaodong Yu,Jihao Fan,Shengquan Zheng,Linlin Ma,Xiaojing Liu,Yue Wu,Chuangqi Zhao,Lei Jiang
High strength/toughness nanocomposites are increasingly in demand due to the development needs of high-end applications. However, the aggregation and random orientation of nanofillers and the weak crosslinking of the polymer matrix lead to the degradation of the mechanical properties of nanocomposites. Here, we present a strategy to prepare chitosan-based nanocomposites with aligned nanosheets via the in situ photo-crosslinking of modified chitosan. The well-dispersed and highly aligned nanosheets, as well as the dense covalently crosslinked network between the modified chitosan chains, effectively improve the mechanical properties of the prepared nanocomposites. For example, the chitosan-based nanocomposite films exhibit a tensile strength of up to 340.6 ± 13.4 MPa, a Young's modulus of 8.2 ± 0.2 GPa and a toughness of 22.0 ± 2.5 MJ m−3, which are 4.2, 4.8 and 1.8 times higher, respectively, than those of pure chitosan films. Moreover, the thermal decomposition temperature of the chitosan-based nanocomposite films reaches 286.8 °C, which is 48.5 °C higher than that of pure chitosan films. We consider that our strategy, which constructs a crosslinked chitosan structure with aligned nanofillers, could lead to the development and application of the bio-based composites with excellent mechanical properties.
研究领域:
材料科学
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生物工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
·
IF 16.744
Jun Chen,Jianjian Wu,Yaosong Zeng,Zhikai Liang,Guangjin Chen,Bei Liu,Zhi Li,Bin Deng
Self-preservation effect of hydrate is an advantage for gas storage by using hydrate-based technology. Unlike focusing on guest molecules in previous publications, deuterium oxides (D 2 O) were introduced as one of host molecules to form methane hydrate. Methane hydrate dissociated percentage was 92.2% after 12 h of dissociation at 273.7 K without the addition of D 2 O, while the methane hydrate dissociated percentage decreased to 55.2 % with the addition of 30 wt% D 2 O. The methane hydrate dissociated percentage reduced to 15.7% when methane hydrate formed in D 2 O system. The results suggested that the self-preservation effect of methane hydrate was improved to above 273.2 K for the first time since this abnormal phenomenon was found in 1986. The temperature of self-preservation effect for (CH 4 + D 2 O) hydrate was improved at least 3.5 K higher than that for (CH 4 + H 2 O) hydrate. From the simulation results, some (D 2 O + H 2 O) mixed cages with different D 2 O and H 2 O molecules formed, and CH 4 inserted into the mixed cages to form CH 4 hydrate as sI structure. The (D 2 O + H 2 O) mixed cages may explain the self-preservation effect of (CH 4 + D 2 O + H 2 O) hydrate above 273.2 K to some extent. Finally, it was also found from the simulation results that (CH 4 + D 2 O + H 2 O) hydrate not only formed from hydrate/(D 2 O + H 2 O) contact, but also nucleated independently.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Erhai An,Yihong Tan,Kehua Han,Xiaoxia Li,Xiong Cao,Yingxin Tan,Peng Deng
Molecular perovskite energetic material DAP-4 is seen as a potential high-energy oxidant due to its high energy, high density, high oxidation capacity, and facile preparation technology. However, optimizing its energy release and reducing its thermal decomposition temperature are huge challenges for its future application. In this work, the role of iron (Fe) nanospheres in the energy release of DAP-4 was studied. Our research has shown that Fe powder can not only serve as a fuel to promote combustion, but also as an important catalyst to significantly improve the thermal decomposition, energy release, and burning rate of DAP-4. By adding 25% Fe nanospheres, the decomposition temperature of DAP-4 was reduced to 299.7 °C, which is the most reduction by 84.7 °C from 384.4 °C (raw DAP-4) to 299.7 °C (DAP-4/Fe-5 with 25wt% Fe nanospheres) was obtained. The decomposition activation energy also decreases by at least 69.5 kJ mol −1 from 229.4 kJ mol −1 (DAP-4) to 159.9 kJ mol −1 (DAP-4/Fe-1 with 5wt% Fe nanospheres). The combustion performance of DAP-4/Fe composites is significantly improved by a 4∼5 times shorter burn rate. The energy-releasing mechanism of DAP-4 with the presence of Fe nanospheres was proposed. Fe x O y at the surface of Fe nanospheres played an important role in the energy releasing of DAP-4. This work showed a new idea for the potential application of molecular perovskite energetic materials.
研究领域:
材料科学
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2019
·
IF 4.561
Dongren Cai,Nisakorn Saengprachum,Zhipeng Lin,Ting Qiu
In this study, a molecular simulation (Gaussian03) was used to analyze the chemical structure of 4-dimethylaminopyridine (DMAP) to investigate its use for the synthesis of ionic liquids (ILs). Based on DMAP, a series of new ILs was prepared and characterized by fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance ( 1 H-NMR), thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC). The density data of the studied ILs were measured from 328.15 K to 358.15 K, p = 0.101 MPa. It is shown that density decreases with an increase in the temperature and the alkyl chain length of cations. And density is also affected by the anion type. Furthermore, the volume of ions, NBO charges, and the interactions of anions and cations were calculated by Gaussian03 to explain the obtained density results. The second-order polynomial equation was adopted to correlate the relationship of density and temperature. Then, an isobaric thermal expansion coefficient , molecular volume, and lattice potential energy were obtained from the density data. Viscosity was determined from 323.15 K to 368.15 K, p = 0.101 MPa. It is determined that the viscosity of ILs decreases with an increase in the temperature but increases with an increase in the alkyl chain length of cations. The temperature dependence of viscosity was described by the Vogel-Fulcher-Tamman (VFT) model, and the activation energy of viscous flow ( E η ) was obtained. Furthermore, the decomposition temperature ( T d ), glass transition temperature ( T g ), and melting temperature ( T m ) of ILs were obtained from the results of TGA and DSC.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Defence Technology
·
2021
·
IF 3.172
Song Zhang,Le-wu Zhan,Guang-kai Zhu,Yi-yi Teng,Yu Shan,Jing Hou,Li Bin-dong
Nano-TATB was developed in microchannels by physical method and chemical method, respectively. The effects of total flow rate, number of microreactor plates, solvent/non-solvent ratio and temperature on the particle size of TATB in the physical method were studied. Prepared TATB were characterized by Nano Sizer, Scanning Electron Microscopy, Specific surface aperture analyzer, X-ray diffraction, Fourier transform infrared spectroscopy and Differential Scanning Calorimetry. The results show that the TATB obtained by physical method and chemical method are spherical, with average particle size of 130.66 nm and 108.51 nm, respectively. Specific surface areas of TATB obtained by physical and chemical methods are 21.37 m 2 /g and 21.91 m 2 /g, respectively. Compared with the specific surface area of micro-TATB (0.0808 m 2 /g), the specific surface area of nano-TATB is significantly increased. DSC test results show that the smaller the particle size of TATB, the lower the thermal decomposition temperature. In addition, by simulating the mixing state of fluid in microchannels and combining with the classical nucleation theory, the mechanism of preparing nano-TATB by microchannels was proposed.
研究领域:
材料科学
·
化学工程
·
爆炸物研究
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Teng Zhang,Hongbin Shi,Yabing Zhang,Qing Liu,Weiyang Fei,Tao Wang
Hollow flower-like nickel particles were prepared by a facile polyol method, and applied to solid propellant as combustion promoter. Ni[C 2 H 4 (NH 2 ) 2 ] 3 (COOH) 2 complex was used to fabricate hollow flower-like intermediate in ethylene glycol (EG), and then the intermediate was calcined and auto-reduced in nitrogen to obtain the hollow flower-like nickel particles. The hollow particles' shell thickness is about 120 nm, and the petals' thickness of the flower structure is about 10 nm. Importantly, the hollow spheres' diameter can be accurately controlled from 200 nm to 2 μm by adjusting the concentration of complex Ni[C 2 H 4 (NH 2 ) 2 ] 3 (COOH) 2 in the reaction solution. The growth of the hollow flower-like particles was illustrated as an extraordinary growth-shrink-collapse process by analyzing the intermediate's morphologies as reaction going on. By adding a certain amount (typically 5 wt%) of the prepared nickel powders, the exothermic decomposition of ammonium perchlorate, which is the main component of solid propellant, was well promoted. The decomposition temperature was decreased by about 140 °C, and the exothermic peak at higher temperature shifted to the lower temperature range, heat released of AP's decomposition also increased by about 150%.
研究领域:
材料科学
·
燃烧与推进
✓ 已验证
产品关联
DOI
高影响因子
RARE METALS
·
2024
·
IF 9.6
Ning Hui-Long,Liang Chao-Ping,Qiang Shan-Shan,Li Jie-Xiang,Tang Sheng,Li Ye-Tao,Sun Wei,Yang Yue
Iron disulfide (FeS 2 ) has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau. However, low thermal decomposition temperature, poor conductivity and inferior actual specific capacity limit its wide applications. Herein, we report a gold-doped FeS 2 (FeS 2 -Au), which not only reduces the band gap of the FeS 2 crystals but also enriches the electron transport path of FeS 2 by the formation of Au nanoparticles. First-principles calculation shows that the diffusion energy barrier of lithium-ion is reduced after the Au-doped FeS 2 . In addition, Au increases the electron cloud density around sulfur atoms, which helps to enhance the stability of Fe-S covalent bonds and thus results in better thermal stability of FeS 2 . When the Au content is 130 μg·g −1 (FeS 2 -Au 4 ), the thermal decomposition temperature (TG 5% ) of FeS 2 -Au is 72.2 °C higher than that of pristine FeS 2 . At a discharge temperature of 500 °C, a current density of 200 mA·cm −2 and a cutoff voltage of 1.4 V, FeS 2 -Au 4 demonstrates superior specific capacity and high specific energy compared to FeS 2 . More precisely, the specific capacity of FeS 2 -Au 4 attains a value of 379 mAh·g −1 , with a corresponding specific energy of 714 Wh·kg −1 . In contrast, the discharge specific capacity and specific energy of FeS 2 are lower, amounting to 348 mAh·g −1 and 656 Wh·kg −1 , respectively. This study offers a novel approach to enhancing the electrochemical performance of FeS 2 in high-temperature molten salt electrochemical systems (thermal batteries), thereby laying a solid foundation for its potential practical application. Graphic abstract
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Zhongxuan Lin,Zhenluo Yuan,Huanhuan Zhang,Shuyan Guan,Xiaojiao Wang,Shiqian Zhao,Guangxin Fan,Yanping Fan,Baozhong Liu
Lowering the dehydrogenation temperature and maintaining high dehydrogenation capacity are greatly hindering the practical application of α-AlH 3 for the hydrogen fuel cell industry. Herein, the layered accordion-like V 2 C MXene is synthesized and doped into α-AlH 3 by mild ball milling . The 1 wt.% V 2 C-catalyzed α-AlH 3 possesses excellent dehydrogenation performance with a low initial decomposition temperature of 70.5 °C and a high hydrogen release capacity of 8.1 wt.%. Furthermore, 7.8 wt.% of hydrogen could be quickly released from α-AlH 3 -1 wt.% V 2 C composite within 15 min at 120 °C, with a lower activation energy of 69.5 kJ/mol than that of as-received sample. The excellent dehydrogenation performance is attributed to the high activity of the zero valence V catalyst which is transformed from the multivalent V during ball milling and to promote dissociation and reorganization of hydrogen. This effective approach significantly enhances the dehydrogenation of α-AlH 3 , providing a hopeful approach for modifying metal hydrides .
研究领域:
材料科学
·
无机化学
·
能源化学
·
纳米材料
·
储氢材料
✓ 已验证
DOI
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2024
·
IF 1.6
Xiangzhou Miao,Baijun Yan
In this study, thermodynamic calculations indicate that using silicon carbide (SiC) as an additive for the reductive decomposition of industrial by-product (IBP) gypsum is a feasible method to lower decomposition temperature and avoid the generation of liquid phase. Experimental results show that the decomposition rate of IBP gypsum exceeded 90% at 950°C for 2 h, while avoiding the generation of liquid phase. In addition, it was found that an intermediate product, 2Ca 2 SiO 4 ·CaSO 4 , was generated during the decomposition process. Through the reaction mechanism and kinetics analysis of IBP gypsum and SiC, the decomposition process can be divided into two steps. The first step was the conversion of CaSO 4 to 2Ca 2 SiO 4 ·CaSO 4 (decomposition rate <60%), and the chemical reaction was the controlling step. The second stage was the conversion of 2Ca 2 SiO 4 ·CaSO 4 to Ca 2 SiO 4 (decomposition rate >60%), and three-dimensional diffusion was the controlling step. This novel method not only successfully lowered the decomposition temperature of IBP gypsum, but also avoided liquid phase generation.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）