CHINESE JOURNAL OF POLYMER SCIENCE
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2021
·Vol. 39
·期 8
·966-974
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IF 3.603
Feng Li-Dong,Bian Xin-Chao,Li Gao,Chen Xue-Si
The effect of exogenous hydroxyl, carboxyl groups and/or Sn 2+ on pyrolysis reactions of poly(L-lactide) (PLLA) was investigated by thermogravimetric analysis (TGA). The activation energy ( E a ) of pyrolysis reactions was estimated by the Kissinger-Akahira-Sunose method. The kinetic models were also explored by the Malek method, and the random degradation behavior was determined by comparing the plots of In{-In[1 - (1 - w ) 0.5 ]} versus 1/ T for experimental data from TGA with model reactions. The pyrolysis reaction rate of PLLA was affected slightly by exogenous hydroxyl and carboxyl groups at lower levels of Sn with 65–70 mg·kg -1 but increased appreciably in the presence of extraneous Sn 2+ , -COOH/Sn 2+ , or -OH/Sn 2+ . The E a values for the pyrolysis reactions of the PLLAs that provided lactide were different under the catalysis of Sn 2+ in different chemical environments because Sn 2+ can form the new Sn-carboxylate and Sn-alkoxide with exogenous carboxyl and hydroxyl groups, which were different in steric hindrance for the formation of activated complex between Sn 2+ and PLLA. Under the catalysis of Sn 2+ , a lactide molecule can be directly eliminated selectively at a random position of PLLA molecular chains, and the molecular chain of PLLA cannot change two PLLA fragments at the elimination site of lactide. However, it was regenerated into a new PLLA molecule with the molecular weight reduced by 144 g·mol -1 .
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
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2020
·
IF 5.627
Yan Zhang,Xiaoyuan Zhang,Chuangchuang Cao,Jiabiao Zou,Tianyu Li,Jiuzhong Yang,Lili Ye,Yuyang Li
This work reports an experimental and kinetic modeling investigation on the flow reactor pyrolysis of iso -butylbenzene and tert -butylbenzene at 0.04 and 1 atm. Pyrolysis products were detected and identified using synchrotron vacuum ultraviolet photoionization mass spectrometry , and their mole fractions versus heating temperature were measured. High-pressure-limit and pressure-dependent rate constants of unimolecular decomposition reactions of iso -butylbenzene were calculated in this work using the same method as the theoretical calculation investigation on similar reactions of n -butylbenzene, sec -butylbenzene and tert -butylbenzene reported by Belisario-Lara et al. [ J. Phys. Chem. A , 122 (2018) 3980–4001]. Furthermore, a pyrolysis model of four butylbenzene isomers was developed from our previous models of n -butylbenzene and sec -butylbenzene and validated by the present experimental data. Modeling analysis was performed to reveal key pathways in fuel decomposition and polycyclic aromatic hydrocarbon (PAH) formation of iso -butylbenzene and tert -butylbenzene. The dominant decomposition reactions of iso -butylbenzene and tert -butylbenzene under pyrolysis conditions are benzylic C C bond dissociation reactions, while the major products in pyrolysis process are produced by β - scission reactions of primary radical products. Fuel-specific pathways are found to strongly affect the formation of PAHs, especially for indene, naphthalene and phenanthrene. Fuel isomeric effects on the pyrolysis of four butylbenzene isomers were also analyzed with special concerns on the fuel decomposition and PAH formation processes. Different sidechain structures result in different distributions of major products, while different formation pathways and concentrations of precursors lead to different formation tendency of typical PAHs.
研究领域:
化学工程
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燃料化学
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DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
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2018
·Vol. 135
·期 25
·46206
·
IF 1.901
Yawen Huang,Yu Yang,Jiajun Ma,Junxiao Yang
Fe- and P-based compounds have demonstrated promising performance in enhancing flame retardancy of epoxy resins. In this context, this work focuses on the preparation of new Fe/P hybridized nanomaterials and their effect on flame retardancy of epoxy resins. The Fe/P hybrids were facilely prepared via forming ferric phosphinates and phosphonates using hydrothermal reaction. Attractively, ferric phosphinates and phosphonates exhibit the morphology of 1D nanorod and 2D nanosheet, respectively. When incorporating these two fillers in epoxy resin, the limiting oxygen index values of composites were enhanced to above 28 and the composites exhibited self-extinguishing behavior, thus indicating greatly improved fire resistance. Further investigation revealed that the flame retarding behavior, in particular for ferric phosphonate nanosheets, took place mainly in gas phases via delaying the release of flammable gas. Attractively, it was found that the Fe/P hybrids took part into the pyrolysis reaction of epoxy resins through forming Fe O and P O bonds. This finding may provide a new insight to design a series of high performance flame retardants for epoxy resins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46206.
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
Frontiers in Chemistry
·
2025
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IF 4.2
Dan Chen,Haitao Chen,Haowei Sun,Yifei Man,Jie Long,Mengying Liu,Jieyun Cai,Dan Li,Shibin Xu,Kai Liu,Shuqi Wang
Introduction: This study focused on three kinds of cigar tobacco leaves (Yunxue 6, Yunxue 36, Yunxue 2) produced in Yunnan region, and through the systematic analysis of their physicochemical properties and aroma components of the smoke, the transformation pattern of aroma compounds and their origins during combustion were deeply investigated.Methods: In the experiments, gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS) techniques were used to comprehensively qualitatively and quantitatively analyze the volatile constituents in the tobacco and its smoke, and combined with the conventional chemical composition detection, to reveal the physicochemical properties of Yunnan cigar tobacco and its influence mechanism on the smoke flavor.Results: Yunnan cigar tobacco exhibits distinct chemical characteristics with low sugar (0.12%–0.16%), high nitrogen (2.84%–4.56%) and alkaloid (2.32%–5.56%) contents, along with imbalanced nitrogen-alkali and potassium-chlorine ratios, affecting its combustion and sensory properties. Smoke analysis identified 144 volatile compounds, predominantly heterocyclic, aromatic and olefinic substances, with elevated pyrazines and pyridines contributing roasted, nutty and smoky notes. GC-O-MS analysis revealed 51 key aroma-active components, demonstrating greater complexity in core tobacco (YXYY) than wrapper tobacco (DHYY, PEYY).Discussion: Combustion transforms precursors (carotenoids, cedranes, phenylalanine) into characteristic aromas through pyrolysis and Maillard reactions, enhancing flavor complexity. This study first elucidates the chemical basis of Yunnan cigar’s characteristic aroma, providing theoretical support for quality improvement, process optimization and product differentiation in domestic cigar production. It fills research gaps in Chinese cigar aerochemistry and establishes a foundation for precision cultivation (e.g., chlorine regulation) and targeted fermentation processes to enhance cigar quality.
研究领域:
食品化学
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分析化学
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农学
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风味化学
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植物科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2023
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IF 6
Shi-yu Feng,Kai Li,Ting Huang,Cheng-bo Zhang,An-qing Zheng,Yan-qin Huang,Shi-guan Yang,Qiang Lu
This study presented a novel method for the simultaneous generation of monophenol chemicals and carbon-based CO 2 adsorbent from polycarbonate (PC) by using salt solution-enhanced pyrolysis. The regulatory functions of several factors on the production of 4-isopropenylphenol (IPP) and phenol were investigated using a laboratory-scale pyrolysis reactor , including salt solution type (neutral, acidic, and alkaline), solution concentration, and pyrolysis temperature. The results revealed that the Na 2 CO 3 solution exhibited the best ability to enhance the preparation of IPP and phenol. At Na 2 CO 3 concentration of 1 mol/L and pyrolysis temperature of 600 °C, the optimum yields of IPP and phenol reached 28.83 wt% and 33.77 wt%, respectively. The pyrolysis char (PCSC) obtained under this condition exhibited good CO 2 adsorption behavior with a maximum adsorption capacity of 1.75 mmol/g at 30 °C because of its well-formed porous structure and copious oxygen-containing functional groups.
研究领域:
化学工程
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环境科学
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材料科学
✓ 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）