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New Insight into Competition between Decomposition Pathways of Hydroperoxymethyl Formate in Low Temperature DME Oxidation

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Li-li Xing Xiao-yuan Zhang Zhan-dong Wang Shuang Li Li-dong Zhang National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

Hydroperoxymethyl formate is a crucial intermediate formed during the low-temperature oxidation of dimethyl ether. The decomposition pathways of HOOCH2OCHO were calculated at QCISD(T)/CBS//B3LYP/6-311++G(d,p) level. The temperature- and pressure-dependent rate constants are computed using microcanonical variational transition state theory coupled with the RRKM/master equation calculations. The calculations show that a pathway leads to the formation of formic acid and a Criegee intermediate does exist, besides the direct dissociation channel to OH and OCH2OCHO radicals. However, formation of the Criegee intermediate has never been considered as an intermediate in dimethyl ether combustion before. The computed rate constants indicate that the newly confirmed pathway is competitive to the direct dissociation route and it is promising to reduce the low-temperature oxidation reactivity. Also electronic effect of groups, e.g. -CHO and O atom, is taken into account. Moreover, Hirshfeld atomic charge and natural bond order analysis are performed to explain this phenomenon from a perspective of chemical nature.

关键词： Hydroperoxymethyl formate RRKM/master equation calculations Low temperature oxidation Dimethyl ether chain branching

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Determining Role of the Branched-chain Reaction Mechanism in Combustion, Explosion and Detonation of Gases

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Journal of Chemistry and Chemical Engineering 2013年第6期7卷 577-590页

作者： V. V. Azatyan Institute of Structural Macrokinetics and Material Science of Russian Academy of Sciences Chernogolovka 142432 Russia

The role of branching-chain mechanism in gas phase combustion is considered. The results of experimental and theoretical investigations show that contrary the accepted for a long time views, branching-chain mechanism of the reaction, competition of chain branching and termination determine the origin and features of gas phase combustion of almost all compounds not only at pressures below atmospheric dozen times, but also at atmospheric and elevated pressures, in conditions of any self-heating. The latter becomes important in the course of developing chain combustion and enhances the chain avalanche. Kinetic methods for controlling combustion, explosion and detonation of gases have been developed by taking into account the decisive role of chain avalanche in these processes. The approach is based on purposeful variation of the rates of the competing reactions of chain branching and termination by means of special small additives. Suggested methods enable not only prevent combustion and explosion, but also adjust the intensity of the process, deflagration to detonation transition and destroy stationary detonation wave at a given distance from the place of its origin.

关键词： chain branching termination avalanche inhibition detonation shock wave.

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支化聚乳酸的微纤化及其结构与血液相容性研究

支化聚乳酸的微纤化及其结构与血液相容性研究

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2014年全国高分子材料科学与工程研讨会

作者：李正秋赵晓文叶林四川大学高分子研究所高分子材料工程国家重点实验室

＜正＞聚乳酸（Poly（lactic acid）,PLA）是一种具有良好生物降解性和相容性的高分子材料,已被美国FDA批准用于人体,成为组织工程领域中最具广泛应用前景的材料之一。但PLA分子结构中含有大量的酯键,降低了其血液相容性及抗凝性,使其... 详细信息

＜正＞聚乳酸（Poly（lactic acid）,PLA）是一种具有良好生物降解性和相容性的高分子材料,已被美国FDA批准用于人体,成为组织工程领域中最具广泛应用前景的材料之一。但PLA分子结构中含有大量的酯键,降低了其血液相容性及抗凝性,使其在作为血管材料等与血液直接接触材料应用方面受到限制;另一方面,其性脆,力学强度较低,难以满足医疗、修复人体部件的要求。为此,本文首先通过反应性加工制备具有支化结构的PLLA材料,以提高其

关键词： poly(L-lactic acid)(PLLA) chain branching microfibrillar self enhancement blood compatibility

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