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通过负离子与RAFT机理转换法合成嵌段序列可控的三嵌段共聚物

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高分子学报 2015年第8期25卷 973-981页

作者：陈李峰何军坡复旦大学高分子科学系聚合物分子工程国家重点实验室上海200433

利用负离子和可逆加成-断裂链转移(RAFT)聚合之间的机理转换,通过顺序加料制备了含有聚异戊二烯(PI)、聚苯乙烯(PS)和聚N-异丙基丙烯酰胺(PNIPAM)的ABC、ACB以及BAC序列的三嵌段共聚物.机理转换系通过将负离子聚合产物活性端基与二硫化... 详细信息

利用负离子和可逆加成-断裂链转移(RAFT)聚合之间的机理转换,通过顺序加料制备了含有聚异戊二烯(PI)、聚苯乙烯(PS)和聚N-异丙基丙烯酰胺(PNIPAM)的ABC、ACB以及BAC序列的三嵌段共聚物.机理转换系通过将负离子聚合产物活性端基与二硫化碳和卤代烃反应,将其转化成双硫酯基团,并作为大分子RAFT试剂,调控第二或第三嵌段的合成.通过调节不同单体的聚合顺序,制备了用同种聚合方法难以制备的、嵌段序列可控的三嵌段共聚物.用体积排除色谱(SEC)和核磁共振谱(NMR)等对产物进行了表征.

关键词：三嵌段共聚物负离子聚合 RAFT聚合机理转换活性聚合

基于负离子-RAFT机理转换合成两亲性高度支化嵌段共聚物

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高分子学报 2017年第2期27卷 283-293页

作者：蒲新明琚振华陈起静安泽胜何军坡复旦大学高分子科学系聚合物分子工程国家重点实验室上海200433 上海大学纳米化学与生物学研究所上海200444

报道了一种从引发型单体CX(inimer)出发、通过负离子-RAFT机理转换,制备两亲性高度支化聚合物的方法.首先,用仲丁基锂(s-Bu Li)与双官能团的1,1-二苯基乙烯衍生物MDDPE反应制备inimer,并通过inimer与苯乙烯共聚制备高度支化聚苯乙烯活... 详细信息

报道了一种从引发型单体CX(inimer)出发、通过负离子-RAFT机理转换,制备两亲性高度支化聚合物的方法.首先,用仲丁基锂(s-Bu Li)与双官能团的1,1-二苯基乙烯衍生物MDDPE反应制备inimer,并通过inimer与苯乙烯共聚制备高度支化聚苯乙烯活性负离子;然后将末端负离子通过与CS2和1-溴乙基苯反应,原位转化为双硫酯基团,并作为大分子链转移剂(dendritic-CTA)调控N-异丙基丙烯酰胺(NIPAM)聚合,从而得到含聚苯乙烯(PS)和PNIPAM的两亲性支化嵌段共聚物.用联有光散射的凝聚色谱(GPC-MALLS)以及1H-NMR对产物进行了表征,并通过荧光探针、动态光散射(DLS)、透射电镜(TEM)等技术对两亲性支化嵌段共聚物在的溶液性质和乳化性能进行了研究.结果表明,该聚合物在水溶液中表现出独特的随温度变化的聚集行为,在水/油两相体系中具有极强的乳化能力.

关键词：高度支化聚合物活性聚合机理转换引发型单体两亲性

Microstructure and Mechanical Properties of RAFM-316L Dissimilar Joints by Friction Stir Welding with Different Butt Joining Modes

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 135-146页

作者： Bin he Lei Cui Dong-po Wang Hui-jun Li Chen-Xi Liu Tianjin Key Laboratory of Advanced Joining Technology School of Materials Science and EngineeringTianjin UniversityTianjin 300354China

Dissimilar welded joints of reduced activation ferritic/martensitic(RAFM)steel and 316 L austenitic stainless steel were prepared by friction stir welding with different butt joining modes and welding *** weld quality of the joint was improved by placing the 316 L steel on the advancing side and the RAFM steel on the retreating side,and using a relatively high rotational speed of 400 *** microstructure of the stir zone on the 316 L steel side consisted of single-phase austenite,and the microstructure of the stir zone on the RAFM steel side mainly consisted of lath martensite and equiaxed ferrite.A mechanical mixture of the two steels and diffusion of Cr and Ni could be detected near the bonding *** of Ni from the 316 L steel to the RAFM steel resulted in the formation of a dual-phase structure consisting of austenite and *** as-welded joints showed good strength and ductility at room temperature and 550°C,which were nearly equal to those of the 316 L base *** heat-affected zone on the RAFM side had the lowest impact toughness throughout the weld with a value of 13.2 J at-40°C,~52%that of the RAFM base material.

关键词： Friction stir welding Dissimilar joint RAFM steel 316L steel Microstructures Mechanical properties

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中国高分子合成化学的研究与发展动态

高分子学报 2019年第10期50卷 1083-1132页

作者：安泽胜陈昶乐何军坡洪春雁李志波李子臣刘超吕小兵秦安军曲程科唐本忠陶友华宛新华王国伟王佳郑轲邹文凯吉林大学化学学院长春130012 中国科学技术大学高分子科学与工程系合肥230026 复旦大学高分子科学系聚合物分子工程国家重点实验室上海200433 青岛科技大学高分子科学与工程学院青岛266042 北京大学化学与分子工程学院北京分子科学国家研究中心北京100871 大连理工大学精细化工国家重点实验室大连116024 华南理工大学发光材料与器件国家重点实验室广州510640 香港科技大学化学系香港中国科学院长春应用化学研究所生态环境高分子材料重点实验室长春130022

高分子合成化学是主要研究高分子量化合物的分子设计、合成和改性等内容的科学,它为人类社会进步、生活水平提高及国家安全提供了必不可少的物质保障.中华人民共和国成立70年来,中国学者为推动此领域的发展作出了积极贡献,在设计合成新... 详细信息

高分子合成化学是主要研究高分子量化合物的分子设计、合成和改性等内容的科学,它为人类社会进步、生活水平提高及国家安全提供了必不可少的物质保障.中华人民共和国成立70年来,中国学者为推动此领域的发展作出了积极贡献,在设计合成新单体和聚合物、研发高效且环境友好新型催化剂、发展新的聚合反应、探索新的聚合方法、优化合成路径、开发聚合新工艺、发现新的结构与性能等方面取得了一系列重要的创新成果.本文总结和评述了中国高分子合成化学的研究与动态,并展望了不同聚合反应、高分子拓扑结构控制以及生物质来源单体的设计、合成与聚合等的未来发展.

关键词：高分子合成化学可控聚合反应自由基聚合反应离子聚合反应配位聚合反应开环聚合反应逐步聚合反应拓扑结构生物质来源单体

Numerical investigation of effects of “baffles-deceleration strip” hybrid system on rock avalanches

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Journal of Mountain Science 2019年第2期16卷 414-427页

作者： BI Yu-zhang he Si-ming DU Yan-jun SHAN Jie YAN Shuai-xing WANG Dong-po SUN Xin-po Institute of Geotechnical Engineering of Southeast University School of Transportation Southeast University Key Laboratory of Mountain Hazards and Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chinese Academy of Sciences Center for Excellence in Tibet Plateau Earth Sciences University of Chinese Academy of Sciences State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology College of civil engineering Sichuan University of Science and Engineering

Arrays of baffles are usually installed in front of protection site to attenuate the flow energy of rock avalanches in mountainous areas. Optimization design is crucial for efficiency promotion in hazard energy dissipation engineering. In this study, a deceleration strip was added in the baffles protection system to optimize the traditional baffles system. The effects of the "baffles-deceleration strip" hybrid protection system was discussed in detail with the nails number and nails angle. This study presents details of numerical experiments using the discreteelement method(DEM). The effect of the optimization of hybrid protection system(nail angle and nail number) were investigated specifically, especially the impact force that avalanches exerted on structures. The results show that the maximum impact forces and kinetic energy of the rock avalanches decreases with the increase of the number and angle of the nail. Moreover, the distance between the toe and the bearing structure(L_m) is also a key factor. The shorter the distance L_m(30 m) is, the higher the maximum impact force are. The longer the distance L_m(70 m) is, the lower the maximum impact force are. Under the same size of the nails, increasing the numbers can enhance the dissipation ability of the hybrid protection system. Meanwhile, increasing itsangle can also enhance the dissipation ability. There are three key ways for nails attenuate rock avalanches:(i) block the fine particles directly;(ii) form the particles bridge between nails and baffles;(iii) dissipate the coarse particles energy directly. The effect of segregation in rock avalanches is crucial for the energy dissipation mechanism, which is a key factor to optimize the traditional baffle system.

关键词： Rock avalanches Baffles Hybrid system Energy dissipation Impact force

Geo-engineered buffer capacity of two-layered absorbing system under the impact of rock avalanches based on Discrete Element Method

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Journal of Mountain Science 2016年第5期13卷 917-929页

作者： BI Yu-zhang he Si-ming LI Xin-po WU Yong XU Qiang OUYANG Chao-jun SU Li-jun WANG Hao Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences & Water Resources Ministry Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences State Key Laboratory of Geo-Hazard Prevention and Geo-Environment Protection Chengdu University of Technology College of Environment and Resources Fuzhou University

Many rock avalanches were triggered by the Wenchuan earthquake on May 12, 2008 in southwest China. Protection galleries covered with a single soil layer are usually used to protect against rockfall. Since one-layer protection galleries do not have sufficient buffer capacity, a two-layered absorbing system has been designed. This study aims to find whether an expanded poly-styrol （EPS） cushion, which is used in the soil-covered protection galleries for shock absorption, could be positioned under dynamic loadings. The dynamic impacts of the two-layered absorbing system under the conditions of rock avalanches are numerically simulated through a 2D discrete dement method. By selecting reasonable parameters, a series of numerical experiments were conducted to find the best combination for the two- layered absorbing system. The values of the EPS layer area as a percentage of the total area were set as 0% （Sl）, 22~ （S2）, and 70% （$3）. 22~ of the area of the EPS layer was found to be a reasonable value, and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system. The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system. The soil layer can absorb the shock energy effectively and S2 （0.4-m thick EPS cushion covered with soil layer） is the most efficient combination, which can reduce the impact force, compared with the other combinations.

关键词： Discrete element method Buffer capacity Dynamic simulation Impact force Two-layered absorbing system

Numerical Simulation of 4H-SiC Metal Semiconductor Field Transistors

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Chinese Physics Letters 2011年第7期28卷 316-318页

作者： Kuang-po HSUEH Shih-Tzung SU jun ZENG Department of Electronics Engineering Vanung UniversityChung-Li 32061TaiwanChina R&D Department InPowerSemiconductor Corp.LtdHong KongChina

This work simulates the performance of 4H-SiC MESFETs and establishes the optimum device structure for dc and rf applications that operate at high *** with various channel doping,buffer layer doping,recess thickness,gate-to-drain spacing and temperatures of operation are *** simulation results reveal that a p-type buffer layer of 5×10^(15) cm^(−3) and a channel layer of 1×10^(17) cm^(−3 )yield favorable *** cut-off frequency is 22.53 GHz,the maximum transconductance is 50.55 mS/mm,the drain saturation current is 239.76 mA/mm and the breakdown voltage is 70.40 *** breakdown voltages increase to 90.2 V as the gate-to-drain spacing increases to 1µ*** on these simulation results,new 4H-SiC MESFET designs can be calibrated.

关键词： drain breakdown MESFET

Microstructure and finite element analysis of hot continuous rolling of doped tungsten rod

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International Journal of Minerals,Metallurgy and Materials 2019年第3期26卷 369-376页

作者： Zheng-jie Shao Hai-po Liu Xiao-chun he Bing Zhou Yang Li Shang-zhou Zhang Meng-jin Li Shu-jun Li School of Nuclear Equipment and Nuclear Engineering Yantai University Weihai Multicrystal Tungsten & Molybdenum Technologies Co. Ltd. Institute of Metal Research Chinese Academy of Sciences

The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved; however, a ring region of abnormal grain growth was present at a distance of about 3/5 R(R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth; this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten.

关键词： doped tungsten continuous rolling microstructure finite element analysis equivalent residual strain

Numerical modeling and dynamic analysis of the 2017 Xinmo landslide in Maoxian County, China

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Journal of Mountain Science 2017年第9期14卷 1701-1711页

作者： OUYANG Chao-jun ZHAO Wei he Si-ming WANG Dong-po ZHOU Shu AN Hui-cong WANG Zhong-wen CheNG Duo-xiang Key laboratory of Mountain Hazards and Surface Process &Institute of Mountain Hazards and Environment (IMhe) Chinese Academy of Sciences Chengdu 610041 China University of Chinese Academy of Sciences Beijing 100049 China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of Sciences Beijing 100101 China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610o59 China Sichuan Engineering Research Center for Emergency Mapping & Disaster Reduction/Sichuan Geomatics Center Chengdu 610041 China

A catastrophic landslide occurred at Xinmo village in Maoxian County, Sichuan Province,China, on june 24, 2017. A 2.87×106 m3 rock mass collapsed and entrained the surface soil layer along the landslide path. Eighty-three people were killed or went missing and more than 103 houses were destroyed. In this paper, the geological conditions of the landslide are analyzed via field investigation and high-resolution imagery. The dynamic process and runout characteristics of the landslide are numerically analyzed using a depth-integrated continuum method and Mac Cormack-TVD finite difference *** results show that the evaluated area of the danger zone matchs well with the results of field investigation. It is worth noting that soil sprayed by the high-speed blast needs to be taken into account for such kind of large high-locality landslide. The maximum velocity is about 55 m/s, which is consistent with most cases. In addition, the potential danger zone of an unstable block is evaluated. The potential risk area evaluated by the efficient depthintegrated continuum method could play a significant role in disaster prevention and secondary hazard avoidance during rescue operations.

关键词： Xinmo landslide Runout Numerical modeling Dynamic process potential risk Highlocality landslide