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REACTION MECHANISM OF BENZOPHENONE-PHOTOINITIATED CROSSLINKING OF POLYETHYLENE

Chinese Journal of Polymer science 2002年第4期20卷 291-307页

作者： Bao-jun Qu state key {2. of fire science and Department of Polymer science and Engineering university of science and technology of china hefei 2.002. china university of science and {2. of china State Key Laboratory of Fire Science and Department of Polymer Science and Engineering Hefei 230026

The radical intermediates, the crosslink microstructures, and the reaction mechanism of benzophenone (BP)-photoinitiated crosslinking of low-density polyethylene (LDPE) and model compounds (MD) have been reviewed in detail. The spin-trapping electron spin resonance (ESR) spectra obtained from the LDPE/BP systems with spin-trap agents show that two kinds of polymer radical intermediates are mainly formed: tertiary carbon and secondary carbon radicals. The spin-trapping ESR studies of MD/BP systems give further evidence that photocrosslinking reactions of PE predominantly take place a sites of tertiary carbon, secondary carbon, and especially allylic carbon when available. The high resolution C-13-NMR spectra obtained from LDPE and MD systems show that the crosslink microstructures have H- and Y-type links and that their concentrations are of the same order. The fluorescence, ESR, C-13 and H-1-NMR spectra from the PE and MD systems demonstrate that the main photoreduction product of BP (PPB) is benzpinacol formed by the recombination of two diphenylhydroxymethyl (K-.) radical intermediates. Two new PPB products: an isomer of benzpinacol with quinoid structure, 1-phenylhydroxymethylene-4-diphenylhydroxymethyl-2.5-cyclobexadiene and three kinds of alpha-alkyl-benzhydrols have been detected and identified. These results provide new experimental evidence for elucidating the reaction mechanism in the BP-photoinitiated crosslinking of polyethylene.

关键词： photocrosslinking mechanism polymer radical intermediates crosslink microstructures photolytic products of benzophenone polyethylene model compound

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A NEW SYNERGIST FOR INTUMESCENT FLAME RETARDANT POLYPROPYLENE

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Chinese Journal of Polymer science 2002年第4期20卷 377-380页

作者： Qiang Wu Bao-jun Qu state key {2. of fire science and Department of Polymer science and Engineering university of science and technology of china, hefei 2.002. china Department of Polymer science and Engineering University of Science and Technology of China State Key Laboratory of Fire Science Hefei 230026

The synergistic effects of silicotungstic acid (SiW12. as a catalyst in the phosphorus-nitrogen compounds AM-based intumescent flame-retardant (IFR) polypropylene (PP) were studied using the limiting oxygen index (LOI), the UL-94 test, thermogravimetric analysis (TGA), real time Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS). The LOI data show that SiW12.added to PP/IFR systems has a synergistic FR effect with an IFR additive named AM. The TGA data show that SiW12.apparently increases the thermal stability of the PP/IFR systems at high temperature (T > 500degreesC). The FTIR results provide the positive evidence that IFR can improve the thermal stability of PP and SiW12.can induce a higher rate of formation of phosphoric acid and its derivatives. The LRS measurements provide useful information on the carbonaceous microstructures. In short, a suitable amount of SiW12.(1.5 wt%) exerts synergistic effects with the IFR by increasing the LOI value and the thermal stability at high temperature and promoting the formation of charred structures on the burning PP surface.

关键词： silicotungistic acid synergistic effect intumescent flame retardant polypropylene

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Recent progress in polymer/layered double hydroxide nanocomposites

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Progress in Natural science:Materials International 2006年第6期16卷 573-579页

作者： DING Peng, CHEN Wei and QU Baojun (state key {2. of fire science and Department of Polymer science and Engineering, university of science and technology of china, hefei 2.002., china) state key {2. of fire science and Department of Polymer science and Engineering University of Science and Technology of China Hefei 230026 China Dalian Institute of Chemical Physics Chinese Academy of Sciences 457 Zhongshan RoadDalian 116023China

New developments in the studies of nanocomposites based on polymer matrixes and layered double hydroxides (LDHs) in recent years are reviewed combining our relative research work, among which the synthesis techniques, the physicochemical characterizations, and the improved material properties are especially discussed. The possible application of polymer/LDH nanocomposites is also proposed.

关键词： nanocomposite layered double hydroxide synthesis characterization structure property.

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Binary fire-extinguishing agent composed of halocarbons and inert gases

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Progress in Natural science:Materials International 2006年第3期16卷 292-296页

作者： ZHOU Xiaomeng, ZHANG Yongfeng and LIAO Guangxuan (state key {2. of fire science, university of science and technology, hefei 2.002., china) state key {2. of fire science University of Science and Technology Hefei 210024 China

C3H2.3Br (132.) is a new kind of Halon replacements developed by our research group. In order to improve the disperse capability of 132., nitrogen was mixed with 132. to form the binary fire-extinguishing agent. In this work, the binary fire-extinguishing agent of nitrogen and 132. was used in experiment and the fire extinguishing efficiency was discussed. In addition, the fire suppression mechanism was investigated and the fire-extinguishing concentration of nitrogen and 132. was also studied.

关键词： Halon replacement nitrogen C3H2.3Br synergistic fire extinguishing concentration.

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Experimental study on fire smoke movement in a multi-floor and multi-room building

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science china(Technological sciences) 2005年第3期48卷 292-304页

作者： ZHONG Maohua 1, 2., LI Peide 2., LIU Tiemin 1 , WEI Xing 1, 2.& LIAO Guangxuan 2.1. National Center of Safety science and technology, {2. Administration of Work Safety, Beijing 10002., china 2. state key laboratory of fire science, university of science and technology of china, hefei 2.002., china National Center of Safety science and technology State Administration of Work Safety Beijing 100029 China

fire smoke movement of multi-floor and multi-room (MFMR) fire was studied at the model test building in {2. key laboratory of fire science (SKLFS). The ingredient, temperature, air pressure difference and air velocity of smoke were measured and analyzed. Meanwhile, the hazard of smoke ingredient to exposed occupants was analyzed based on the national standard, Occupational Exposure Limit for Hazardous Agents in the Workplace (GBZ2.2.02.. The experimental results showed that the maximum temperature difference in MFMR fire was located along the vertical height from the fire source. With the spreading and diffusion of smoke, the temperature of smoke layer would tend to be no difference. In the fire of woodpile and kerosene, the main smoke ingredients such as SO 2., CO and CO 2.would first exceed human’s average physiological limit, while smoke ingredients such as NO and NO 2.would come behind. Because of the higher fluctuation range and frequency of air pressure difference of smoke in multi-layer building fire, the fire smoke would spread around everywhere of the passageway and made the human evacuation more difficult.

关键词： multi-floor and multi-room,fire experiment,smoke spread,smoke toxicity.

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Influence of rarefaction wave on premixed flame structure and propagation behavior

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Progress in Natural science:Materials International 2007年第3期17卷 328-333页

作者： CHEN Xianfeng, SUN Jinhua, LU Shouxiang, CHU Guanquan, YAO Liyin and LIU Yi (state key {2. of fire science, university of science and technology of china, hefei 2.002., china) state key {2. of fire science University of Science and Technology of China Hefei 230026 China

To explore the influence of rarefaction wave on the structure and propagation behavior of the premixed propane/air flame in a rectangle combustion pipe, the techniques of high speed Schlieren photograph method, pressure measurement and so on are used to study the interaction processes between rarefaction wave and flame. Two cases of rarefaction wave-flame interaction were performed in the experiment. The experimental result shows that both the rarefaction waves can cause the flame transition from laminar to turbulent combustion quickly. The cowflow rarefaction wave decreases the flame speed, while the counterflow rarefaction wave leads the flame propagation speed to increasing on the whole, accompanied with sharp vibration.

关键词： gas explosion rarefaction wave flame propagation laminar flame turbulent combustion.

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Distribution of Nb atom in the TiAl+Nb system

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Rare Metals 2001年第1期20卷 5-12页

作者： Xiaodong Ni, Xidong Hui, Guoliang Chen (Applied science School, university of science and technology Beijing, Beijing 100083, china state key laboratory for Advanced Metals and Materials, university of science and technology Beijing, china) Appl. Sci. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Based on MEAM (the modified embedded atom method) potential and an average atom model similar to B-W (Bragg-Williams) method, the distribution of Nb atoms in TiAl+Nb compounds with various composition was calculated. The calculation results showed that Nb atoms prefer to occupy the Ti sublattice of L10 structure for all compounds in question. With increasing atomic fraction of Nb and Al, Nb atoms exhibited a trend of ordered distribution on the Ti sublattice and result in a new L10 derivative superlattice structure.

关键词： Computer simulation Intermetallics Superlattices Ternary systems

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Evolution of Bright Screening-photovoltaic Spatial Optical Solitons

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Chinese Journal of Lasers 2001年第5期10卷 28-33页

作者： LIU Jinsong (state key {2. of Laser technology, Huazhong university of science and technology, Wuhan 430074, china) 华中科技大学激光技术国家重点实验室湖北武汉

A numerical analysis of the dynamical evolution of bright screening photovoltaic (SP) spatial solitons in biased photovoltaic photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle.

关键词： nonlinear optics spatial optical solitons photorefractive effects

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Catastrophe mechanism and classification of discontinuity behavior in thermal science (Ⅰ)——Fold catastrophe

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Chinese science Bulletin 2000年第20期45卷 1813-1817页

作者： XIE Zhikang, FAN Weicheng & WANG Qing’anstate key {2. of fire science, university of science & technology of china, hefei 2.002., china state key {2. of fire science University of Science & Technology of China Hefei China

The mechanism of discontinuity behavior has important significance in the study of thermal science, such as fire, combustion, explosion and heat transfer. This sort of discontinuity behavior and the catastrophe caused by system nonlinearity may be equivalently classified according to the catastrophe model promulgated by catastrophe theory. Under the conditions of uniform temperature and thermal isolation, the self-ignition behavior of a Semenov System can be viewed as a result of the fold catastrophe of the system.

关键词： complexity science nonlinear science thermal science catastrophe classification.

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Effect of Powder Particle Size on the Properties and Microstructure of Ti(C,N)-Based Cermet

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Rare Metals 2001年第1期20卷 47-51页

作者： Yong Zheng, Weihao Xiong (key state {2. of Die technology, Huazhong university of science and technology, Wuhan 430074, china) 华中科技大学材料成形与模具技术国家重点实验室湖北武汉 430074

The influence of raw powder particle size on the properties and microstructures of Ti (C, N)-based cermets has been studied. The conclusions are as follows: The microstructures of cermets were composed of two kinds of grains, the one with black cores surrounded by obvious rim structures, and the other whose cores were white with unconspicuous rim structures and adhesive phase. In the cermet made from fine powders, the amount of grains with white cores was much more than that in cermet made from coarse powders. In addition, their properties were also much better.

关键词： Ti(C, N)-based cermet powder particle size property microstructure

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