MACROMOLECULES
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2017
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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
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2022
·
IF 6.437
Jianwei Zhang,Ling Chen,Liangyou Zhao,Guorui Jin,Weidong He
Nitrogen heterocycles as Nitrogen-rich energetic material has been widely popularized due to their desirable properties like low sensitivities, excellent stability, and lower environmental impact, less erosive and less toxic combustion gases , especially in gun propellant application areas. The focus of this study is on investigating interaction mechanism of 1 H-tetrazole (1 H-TZ) and nitrocellulose (NC) by kinetics methods and TG-DSC-FTIR analysis. The mixture (NC-TZ) between 1 H-TZ and NC was prepared by means of physical blending. DSC experiments indicated that the open and closed environment can generate different and important influence on the chemical reaction between 1 H-TZ and NC. Combined with the change of activation energy , it illustrated that the gas 2 H-tetrazole, the isomer of 1 H-TZ, had a significant influence on the thermal decomposition of NC. In comparison with kinetic models of NC and NC-TZ, it can be found that the addition of 1 H-TZ mainly affected the contribution factor and m value in the first stage. The value of m decreased from 1.00 to 0.15, meanwhile, the contribution factor was decreased from 0.50 to 0.12. It showed that NO 2 , the initial decomposition product of NC, had taken part in the thermal decomposition process of 1 H-TZ. TG-DSC-FTIR experiments indicated that there was a chemical reaction between 2 H-tetrazole and the initial decomposition product of NC, NO 2 , to form CO, N 2 O and HN 3 .
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 19
·9024-9035
·
IF 3.925
Jun Li,Yuehua Cong,Haozhou Huang,Qiankun Shi,Yinggang Jia,Baoyan Zhang
Multiple mesophases, including the smectic A phase (Sm A), chiral nematic phase (N*), and blue phase (BP I), were seen in a series of non-symmetric bent mesogenic dimers containing a cholesteryl benzoate group. FTIR, 1H-NMR, DSC, POM, UV, and XRD were used to analyze the chemical structure and liquid crystal characteristics of the dimers. The phase transition occurred when the azobenzene structure was treated with UV light, changing the structure of the molecules. There is evidence that when the length of the terminal alkoxy chain is longer than the flexible spacer, it exhibits a smectic A phase as well as a chiral nematic phase; however, when the length of the flexible spacer is shorter than the length of the terminal alkoxy chain, it only exhibits a chiral nematic phase.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2021
·
IF 0
Hao-Zhou Huang,Yue-Hua Cong,An Du,Bing Hu,Bao-Yan Zhang
A new series of liquid crystalline dimers containing a cholesteryl group were synthesised, exhibiting multiple mesophases including chiral smectic phases (SmC* and SmA*), twist grain boundary phases (TGBA*), and chiral nematic phase (N*). The chemical structure and liquid crystal properties of the dimers were characterised by FTIR, 1H-NMR, DSC, POM and XRD. It was in evidence that the lengths of the terminal tail and the flexible spacer were the decisive factors of the mesophase behaviours.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
Pigment & Resin Technology
·
2025
·
IF 1.5
Raouf Mahmood Raouf,Ahmed A. Ayash
Purpose The purpose is to investigate the effect of Indium oxide nanoparticles on thermoset epoxy. In more details, the filler used is pure Indium oxide nanoparticles (50 nm) and Fourier transform infrared spectroscopy analysis (FTIR) analyses has been done to understand the structural changes on epoxy network. Also, the effect of Indium oxide on the epoxy matrix is explored comprehensively to encompass the thermal, electrical and mechanical properties. Accordingly, a series of experiments have been conducted and are presented in the next section. Design/methodology/approach In all the experiments, the polymerisation of epoxy was carried out under constant pressure (1 atm) and temperature (30 °C) using a water bath. The monomers of epoxy were mixed according to the stoichiometric ratio recommended by providing Company to ensure getting the optimum properties after curing the samples. To create a mixture, three concentrations (1%, 3% and 5%, w/w) of the indium oxide nanoparticles In2O3 NP were manually added to the polymer solution. After that, the samples were dried for 4 h at 40 °C in a drying oven and then they are post-cured for 24 h at ambient temperature. Findings Interestingly, the FTIR spectra showed that there are aromatic rings in the nanocomposites structure which might be responsible for the notable increase in mechanical strength and thermal stability. Further, an enhancement in electrical properties has been observed. In general, the results are promising and might open up many applications of such system (i.e. Indium oxide/epoxy) in many areas such as conductive coatings, electrical and electronic gadgets, alternative energy……….etc. Originality/value While there are many studies used different types of metal-oxide fillers to produce epoxy nanocomposite, a little amount of work has been reported on indium oxide in the last decade. Most the reported studies are limited to exploring the impact of Indium tin oxide nanopowders on the composite’s electrical and optical properties. Here, the work is different than these studies. The filler used is pure Indium oxide nanoparticles (50 nm) and FTIR analyses has been done. Further, the effect of Indium oxide on the epoxy matrix is explored comprehensively, for the first time, to encompass the thermal, electrical and mechanical properties.
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
THERMOCHIMICA ACTA
·
2023
·
IF 3.5
Yongchen Zhu,Jianwei Zhang,Weidong He
5-Amino-1H-tetrazole (5-ATZ), an environmentally friendly energy-containing material for new propellants, is gradually applied in high-energy propellants and its ionic salt compounds have received wide attention. This study focused on investigating the interaction mechanism of guanidinium-5-aminotetrazole (GA) and nitrocellulose (NC) by kinetic methods and TG-DSC-FTIR analysis. DSC and TG experiments indicated that there was a certain interaction during the pyrolysis process of NC and GA. Comparing the kinetic models of NC and peak 3 in NC-GA, it can be found that the addition of GA mainly affected the m-value and contribution in the second step B→C, and the mechanism function changed from F n to C n,m. TG-DSC-FTIR experiments indicated that the initial decomposition product of NC, NO 2 , participated in the thermal decomposition process of GA, and the two reacted chemically to form CO, N 2 O, which made NO 2 unable to completely oxidize the skeleton of NC to produce CH 2 O, HCOOH.
研究领域:
化学
·
材料科学
·
能源与推进剂研究
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2022
·
IF 4.598
Mingjun Lu,Rongting Guo,Wei Li,Yiju Lv,Fushun Tang,Weiyi Feng,Zheng Liu,Guo-Cheng Han,Zhihua Zhan
The interfacial characterization of the cathode material Na 2 FePO 4 F with carbon capping material Na 2 FePO 4 F@C taking bagasse as the carbon source is reported. Both the higher-capacity Na 2 FePO 4 F@C material (93 mAh/g) and lower-capacity Na 2 FePO 4 F material (10 mAh/g) showed different degrees of capacity decay during cycling. The rupture and spontaneous repair process of the solid electrolyte interface (SEI) film resulting in increased impedance and blocked charge transfer, as well as irreversible changes in the surface microstructure of the electrode material after cycling, which are responsible for the decrease in capacity. The XRD and FTIR results before and after cycling shown that the characteristic peaks of the carbon coated material Na 2 FePO 4 F@C and raw material Na 2 FePO 4 F were consistent, indicated that their functional groups and crystalline structures are not the main causes of capacity decay at low cycling times (within 50 cycles).
研究领域:
电化学
·
材料科学
·
能源存储
·
电池技术
·
界面化学
·
无机非金属材料
✓ 已验证
DOI
高影响因子
PROGRESS IN ORGANIC COATINGS
·
2020
·
IF 4.469
Lin Deng,Liuyan Tang,Jinqing Qu
The design and development of macro-photoinitiators applicable to UV system has been attracted increasing attention for their excellent performance of low migration and high compatibility. Herein, four kinds of novel macro-photoinitiators (PI1-PI4) used in UV-curable coatings were synthesized by different isocyanates, 1-hydroxycyclohexyl phenyl ketone (Irgacure 184), 2-hydroxyethyl methacrylate (HEMA) and pentaerythritol triacrylate (PETA). The structures were analyzed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Moreover, the photopolymerization kinetics of the macro-photoinitiators were investigated by real-time FTIR. Results revealed that the macro-photoinitiators display higher curing efficiency, lower migration performance and better compatibility with formulation compositions compared to Irgacure 184. On the other hand, the macro-photoinitiators also served as self-initiating oligomers and had good thermal stability with 10 % weight loss temperatures (T10 %) above 299.7 °C. The UV-cured films consisting of oligomers and tripropylene glycol diacrylate (TPGDA) showed excellent physical properties and high curing efficiency and rapid curing rate.
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
VIBRATIONAL SPECTROSCOPY
·
2023
·
IF 2.5
Liwei Ni,Shiying Yang,Wenze Qiu,Jialei Jin,Qiyue Xu,Shuliang Ye
The reaction pathway of many Paal-Knorr reactions for pyrrolic compounds hasn’t been thoroughly studied and remains controversial. In this work, the synthesis of an important anti-ultraviolet agent N-butoxycarbonyl-2,5-dimethylpyrrole based on the Paal-Knorr reaction was studied via in-situ Fourier transform infrared (FTIR) analysis combined with density functional theory (DFT) calculation. The online spectral data were analyzed using K-means clustering in order to find the characteristic wavenumbers of intermediates. It was found that the reaction with 2,5-hexadione and butyl carbamate are more favorable to form the imine and enamine intermediates by nucleophilic addition, which is different from another Paal-Knorr reaction with 2, 5-hexadione and ethanolamine . In addition, the reaction kinetic model was established through chemometric methods, with parameters of two rate-limiting reaction steps calculated. This approach of FTIR analysis is proven to be an effective tool for mechanism study of organic synthesis.
研究领域:
有机化学
·
物理化学
✓ 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）