MACROMOLECULES
·
2017
·
IF 5.835
Qingsong Lian,Yan Li,Kai Li,Jue Cheng,Junying Zhang
The vulcanization mechanism remains unclear due to the difficulty of characterization and the complexity of the vulcanization systems. In this work, a series of epoxy model systems were used to study the sulfur cleavage behavior, from which the study process of the vulcanization mechanism was significantly simplified and a brand new sulfur-only vulcanization mechanism was revealed by the FTIR and DSC analysis. Our studies suggest that thiyl radicals derived from the homolytic cleavage of sulfur play the dominant role in the vulcanization, while the heterolytic fission of sulfur cannot occur as expected because this reaction needs 200 °C. Nevertheless, sulfur anions, which are easy to be understood derived from the heterolytic cleavage of sulfur, are actually transformed from the thiol groups that are produced through the reaction of thiyl radicals abstracting α-H atoms of allyl groups in rubber, and this maybe the reason that vulcanization mechanism remains controversial for centuries.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Jian Wang,Jie Chen,Yaofeng Mao,Xingquan Zhang,Jun Wang,Fude Nie
Metal fuel with high energy and reactivity is an urgent need for the development of solid propellant, explosive and pyrotechnics. Herein, spherical B/Al/PTFE fuel is designed based on synergistic reaction effect between B/F and Al/F and prepared through the confinement-emulsion-templated method. The combustion reaction performance and pressure output performance of B/Al/PTFE microspheres are much better than their physically mixed counterparts. The synergistic reaction effect between B/F and Al/F on the reaction heat, flame propagation , and pressure output were systematically investigated through adjusting the B/Al mass ratio (30/0∼0/30). The DSC results show that the highest heat of combustion of 4904 J/g can be achieved when the B/Al mass ratio is 21/9. Furthermore, the combustion duration , peak pressure, and pressurization rate are monotonically accelerated from 653 ms, 352.15 kPa, and 305.67 MPa/s to 200 ms, 821.25 kPa, and 1831.18 MPa/s, respectively. This work provides a promising method for the design and preparation of highly composited metal fuel for practical application.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2024
·Vol. 149
·期 10
·4491-4503
·
IF 3
Chen Yongjia,Zhao Yilin,Hua Min,Pan Xuhai,Jiang Huichun,Jiang Juncheng
We investigated the inhibition of thermal runaway of styrene polymerization by DNPB. DNBP is an inhibitor in styrene polymerization reaction. Polymerization is one of eighteen hazardous processes. Styrene polymerization reaction is characterized by high heat production and fast reaction rate. Firstly, differential scanning calorimetry (DSC) and adiabatic calorimetry (ARC) were chosen to study the effect of different mass of DNBP on thermal behavior in non-isothermal and adiabatic environments. Secondly, exploring the inhibitory effect of DNBP at different runaway temperatures using an oil bath reactor. The results showed that when DNBP was at 0.80%, effective inhibition was obtained at different runaway temperatures. Finally, GC/MS and Gauss16 were used to infer the mechanism of inhibition in terms of macroscopic products and microscopic instabilities. The results showed that the products of the oil bath reactor experiments were related to the mass of DNBP, and when DNBP was 0.80%, the products increased and the main reaction was inhibited. Finally, it was deduced that the nitro group undergoes a possible path of direct addition reaction with the styrene radical before bond breaking.
研究领域:
化学工程
·
材料科学
·
安全工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2021
·
IF 6.165
Qingguo Zhang,Sihan Feng,Xinyuan Zhang,Ying Wei
Two novel ionic-liquid-based binary mixture systems of N,N-diethyl-N-(2-methoxyethyl)- N -methylammonium tetrafluoroborate ([DEME][BF 4 ]), or N,N-diethyl- N -methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ([DEME][TFSI]) + γ-butyrolactone (GBL) are prepared over the whole concentration range (mole fraction from 0–1). Some important thermodynamic properties and parameters of the pure ILs and two systems were measured and calculated. The temperature dependences of the transport properties (viscosity and conductivity) were described by the Vogel–Fulcher–Tamman (VFT) equation. The excess molar volumes ( V E ) were obtained from the experimental densities and fitted to Redlich–Kister (R–K) polynomial equation. The DSC analysis, the shifts of the infrared (IR) spectrum, and COSMO–RS methodology based on DFT calculations were combined to explain the interaction information of GBL molecules and cations/anions of the selected systems. The stable optimized structures, interaction energies, and charge distributions were further obtained. Those maybe slight enlighten the application of similar mixture systems in future.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Shiyao Lu,Jian Zhang,Hao Meng,Xiaoyuan Qin,Jianbin Huang,Yehao Liang,Feng-Shou Xiao
Dehydration of methyl lactate (ML) obtained from biomass is a sustainable route for the production of methyl acrylate (MA). Herein, we demonstrate that cesium-exchanged Al-rich Beta zeolite (Cs-Beta) is highly efficient for the dehydration of ML to MA, exhibiting full ML conversion with 87.4% MA yield at 340 °C. In situ FT-IR spectra and kinetic studies provide evidence that the ML dehydration on the Cs-Beta zeolite follows a forward ion-exchange/dehydration/reverse ion-exchange reaction pathway. Model experiments, DFT calculations, TG-DSC analysis, and FT-IR spectra showed that coke formation competes with the dehydration of ML to MA. Kinetic studies and theoretical simulations demonstrate that cesium cations in the micropores of Beta zeolite have a strong steric hindrance, suppressing the formation of oligomers and coke. These results offer new insights for developing highly selective and stable catalysts for the dehydration of ML to MA in the future.
研究领域:
化学工程
·
催化
·
材料科学
·
可持续化学
✓ 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）