氧化锌/石墨烯复合材料的水热制备及其光催化性能

基于石墨烯优异的电子传输特点,本文以石墨烯为载体,醋酸锌为半导体前驱体,通过水热法制备了氧化锌/石墨烯复合材料。对所合成的复合材料进行了X射线衍射(XRD)、红外光谱(FT-IR)、扫描电子显微镜(SEM)、拉曼光谱(Raman)、氮气吸脱附等温曲线及光催化性能测试。结果表明:氧化锌均匀复合在石墨烯表面,两者形成了有效的界面耦合。得益于氧化锌在水热反应过程中形成的高结晶度及与石墨烯之间的界面耦合作用,电子可从氧化锌的价带直接传向石墨烯,因此该复合材料的光降解效率达到了89.84%,相比于商用二氧化钛有了显著提高(47.68%),其光降解一级反应速率常数达到0.012min-1。这种新颖的、具有优异光催化性能的氧化锌/石墨烯复合材料在光催化领域具有较高的潜在应用价值,为构筑其他石墨烯基半导体复合材料提供了新的思路。     

硫化镉/石墨烯/TiO_2纳米棒阵列的光电化学性能

采用水热法在掺氟导电玻璃(FTO)上生长TiO_2纳米棒阵列。通过电化学伏安法将氧化石墨烯还原并沉积在TiO_2纳米棒阵列上,再经过化学水浴沉积硫化镉,形成Cd S/石墨烯/TiO_2阵列复合材料。用X射线衍射仪、扫描电子显微镜及X射线能量色散仪对样品的晶型、形貌以及成分进行分析。通过电化学工作站表征样品交流阻抗、开路电位、光电流响应及光化学能转换效率。结果表明,复合材料的电荷转移电阻约是未修饰的TiO_2纳米棒阵列的1/17,光电流比未修饰的TiO_2纳米棒阵列提高约2.5倍,在外加电压为-0.6 V时可达到2.2%。     

水热法制备三氧化二铝掺杂石墨烯泡沫

石墨烯泡沫与其他纳米材料掺杂是提高石墨烯泡沫性能、拓展石墨烯泡沫应用的重要手段.发展简便的掺杂石墨烯泡沫的方法对石墨烯技术具有重要的意义.本文以氧化石墨烯和偏铝酸钠为原料,采用水热反应一步合成了三氧化二铝掺杂的石墨烯泡沫复合材料.掺杂石墨烯泡沫采用扫描电子显微镜、X射线光电子能谱、红外光谱和孔径结构等技术进行表征.结果表明,氧化石墨烯在水热反应中充分还原,偏铝酸钠在水热反应中有效水解.针状三氧化二铝纳米颗粒均匀掺杂到石墨烯泡沫的多孔结构中,得到比表面积大、掺杂量高的掺杂石墨烯泡沫.     

超声剥离法制备石墨烯纳米片

为降低生产成本,简化工艺流程,实现石墨烯在复合材料中的工程应用,采用超声剥离法对微波膨胀后的石墨进行剥离,制备得到了石墨烯纳米片(GNSs)。采用透射电子显微镜电镜、原子力显微镜、拉曼光谱对得到的GNSs的微观结构与形貌进行了分析。结果表明,通过超声剥离法可以制备出尺寸大、厚度小、结构规整且缺陷少的石墨烯片层材料,为其在复合材料等领域的产业化生产奠定了基础。     

石墨烯/水泥复合材料的制备及电学、压敏性能研究

采用Hummers法制备了氧化石墨烯(GO),并经过1 000℃高温还原制备了还原氧化石墨烯(RGO)。采用红外光谱、拉曼光谱、透射电子显微镜等分析测试方法对GO与RGO的结构进行了表征。进一步将RGO引入水泥中,制备了石墨烯水泥复合材料,并研究了该类复合材料的电学性能和压力敏感性能。结果表明:石墨烯可以作为导电桥梁填充到水泥基体的空隙之中,因而可以显著提高复合材料的电学性能,并且石墨烯水泥复合材料具有典型的压力敏感性能,有望用于材料结构监测。     

氧化石墨烯/丙烯酸酯聚合物乳液复合材料的研究

采用改进的Hummers法获得氧化石墨,超声分散制备出氧化石墨烯溶液,然后加入丙烯酸乳液中制成氧化石墨烯/丙烯酸酯聚合物乳液复合材料.对氧化石墨烯进行XRD、EDS及红外光谱表征;对复合材料成膜进行原子力显微镜表征、热重分析、力学性能以及耐水性测试.结果表明,制备的氧化石墨烯中氧元素含量达35.24％,并且大部分是羟基、羧基和环氧基;当氧化石墨烯用量为乳液用量的0.4％时,复合材料的表面粗糙度提高了87.5％,热分解温度提高了50℃,抗拉强度提高了23％,耐水性也有较好的保持.     

PVA/MMT复合材料结构性能研究

以聚乙烯醇和蒙脱石为原料,采用冷冻干燥法制备出了不同聚乙烯醇含量的聚乙烯醇/蒙脱石纳米复合材料,用X射线衍射(XRD)、扫描电子显微镜(SEM)对复合材料的结构进行了表征.结果表明,聚乙烯醇分子成功进入蒙脱石的层间,实现了在纳米尺度上的复合,在SEM图片上观察到了纳米复合材料的微观结构.     

PANI/SiCNP复合材料的制备及其光热蒸发性能

采用原位聚合法实现了聚苯胺(Polyaniline, PANI)对碳化硅纳米颗粒(Silicon Carbide Nanoparticles, SiCNP)的有效包覆,得到了聚苯胺/碳化硅纳米颗粒的复合材料(PANI/SiCNP)。使用扫描电镜(Scanning Electron Microscopy, SEM)对样品进行形貌结构分析,结果表明：PANI较为均匀地生长在SiCNP表面,PANI/SiCNP直径从SiCNP的20～100 nm增加到100～200 nm,而且随着在复合材料中SiCNP的增加导致有较多的团聚。而且与PANI相比,PANI/SiCNP的热稳定性得到了提升。界面水蒸发测试结果显示,PANI/SiCNP复合材料有着良好的水蒸发速率和水蒸发稳定性。     

聚苯胺/膨润土导电性功能填料的研制

用插层聚合法制备了聚苯胺/膨润土复合材料.以电导率为考核指标,通过正交设计优化了苯胺的加入量、反应温度和反应时间等参数,聚苯胺/膨润土复合材料制备的最佳工艺条件为:苯胺加入量为70%,反应温度为25 ℃,反应时间为6 h,电导率达10-3S/cm.以聚苯胺/膨润土复合材料为导电填料,低分子量聚酰胺为固化剂,固化环氧树脂,聚苯胺复合材料加入量为20%,固化剂的加入量为40%,固化温度为60℃,制得的涂膜电导率达10-5 S/cm,固化物硬度为HB,冲击强度为28 cm,附着力和柔韧性较好,满足抗静电材料的要求.     

层状氮化硼纳米片的制备及表征

基于前驱体合成与氨气氮化两步法,通过对前驱体合成关键参数B源/N源比、分散剂种类、前驱体干燥方式进行调控,实现了大比表面积、少层氮化硼纳米片材料的制备.其优化条件为以硼酸为硼源,尿素为氮源,硼酸与尿素摩尔比为1∶30,甲醇和去离子水作为分散剂,利用真空冷冻干燥方式合成前驱体.将前驱体在氨气气氛下900℃保温3 h合成了氮化硼纳米片.利用X射线衍射测试、X射线光电子能谱测试、拉曼光谱测试、热重分析测试等对合成产物进行了物相和结构表征,利用扫描电子显微镜、原子力显微镜、透射电子显微镜、氮气吸脱附曲线等对合成产物进行了形貌及比表面积表征.结果表明:合成的氮化硼为六方氮化硼纳米片(h-BNNSs),纯度高,形貌类石墨烯,层数为2～4层,厚度平均为1 nm,比表面积为871.8 m2·g-1,单次产物质量平均可达240 mg,合成产物平均产率可达96.7%.该方法简单易操作,实现了大比表面积少层氮化硼的制备,有助于氮化硼在各应用领域的研究,如氮化硼/石墨烯复合材料、纳米电子器件、污染物的吸附、储氢等.     

纳米碳酸钙复合制备高强高韧PVC材料的研究

在水相中对纳米碳酸钙悬浮液进行湿法改性。抽提后改性纳米碳酸钙的红外光谱和热失重分析显示改性剂与纳米碳酸钙之间以化学键结合；将改性纳米碳酸钙应用到聚氯乙烯中，制得了高强、高韧的硬聚氯乙烯纳米复合材料；并使该复合材料在保持加工性能的同时耐热性能也得到提高。扫描电镜分析显示，复合材料冲击断面产生丝状屈服，表现出典型的韧性断裂特征     

内插保温层混凝土空心砌块的热工性能与经济性分析

根据国家对建筑能耗节能50%和节材的要求,目前在夏热冬冷地区对建筑围护结构普遍采用空心砌块以满足对热阻的要求。本文分别对某内插保温层混凝土空心砌块以及将保温层取出的砌块的热阻进行了试验研究,分析了两者热工性能的差异,并对砌块内插保温层的有效性和经济性进行了分析,得出砌块内插保温层的投资可在4~5年内收回;并找出该空心砌块存在的不足,分别针对砌块外部结构和内部构造提出了改进方法,使砌体能够满足夏热冬冷地区对建筑围护结构节能的要求。     

Concrete building blocks made with recycled demolition aggregate

A study undertaken at the University of Liverpool has investigated the potential for using recycled demolition aggregate in the manufacture of precast concrete building blocks. Recycled aggregates derived from construction and demolition waste (C&DW) can be used to replace quarried limestone aggregate, usually used in coarse (6 mm) and fine (4 mm-to-dust) gradings. The manufacturing process used in factories, for large-scale production, involves a “vibro-compaction” casting procedure, using a relatively dry concrete mix with low cement content (≈100 kg/m³). Trials in the laboratory successfully replicated the manufacturing process using a specially modified electric hammer drill to compact the concrete mix into oversize steel moulds to produce blocks of the same physical and mechanical properties as the commercial blocks. This enabled investigations of the effect of partially replacing newly quarried with recycled demolition aggregate on the compressive strength of building blocks to be carried out in the laboratory. Levels of replacement of newly quarried with recycled demolition aggregate have been determined that will not have significant detrimental effect on the mechanical properties. Factory trials showed that there were no practical problems with the use of recycled demolition aggregate in the manufacture of building blocks. The factory strengths obtained confirmed that the replacement levels selected, based on the laboratory work, did not cause any significant strength reduction, i.e. there was no requirement to increase the cement content to maintain the required strength, and therefore there would be no additional cost to the manufacturers if they were to use recycled demolition aggregate for their routine concrete building block production.     

Structural investigations of aquatic humic substances by pyrolysis-field ionization mass spectrometry and pyrolysis-gas chromatography/mass spectrometry

The present state-of-the-art in structural investigations of aquatic humic substances and their fractions such as fulvic and humic acids by pyrolysis-field ionization mass spectrometry is outlined. An integrated approach to interpretation uses complementary data of elemental analysis, functional group determinations, Cu²⁺-complexation, H⁺-capacity and results from u.v.-vis- and FT-i.r.-spectroscopy. Proposed building blocks of the molecular structure are supported by chromatographic investigations using Curie-point Py-GC/MS and the available literature reports. The potential and limitation of the applied methodology are discussed.     

Lateral channeling within rectangular arrays of cubical obstacles

Water channel experiments were conducted with the goal of obtaining better understanding of flows through urban-like arrays of buildings. Particle Image Velocimetry (PIV) was used for comprehensive flow measurements within a modeled simple urban setup. Building arrays were modeled using acrylic blocks whose refractive index is the same as that of salty water. Such a setup allowed for undisturbed laser sheet illumination through the obstacles enabling detailed flow measurements between the obstacles/buildings. Building array size, measurement plane and flow conditions were varied. A novel flow feature, lateral channeling, observed and quantitatively measured, within regular 3×3 and 5×5 arrays of cubes is reported here. A sideways mean outflow from the building array is observed behind the first row of buildings followed by the mean inflow in the lee of all succeeding rows of buildings. When the central building in a 3×3 array is replaced by a building of double height, due to the strong downdraft caused by this tall building, the lateral outflow becomes significantly more intense. When the central building in a 5×5 array is replaced by a building of double height, the building downdraft blocks the lateral inflow to the array. This is the first time that such detailed measurements are available for a mock urban array of finite size—a real three-dimensional case. The newly identified mean flow pattern may be accountable for the initial plume spread within an array of obstacles.     

Navy Demonstration Project

The Navy Demonstration Project is a multi-layered collaborative research project between architects, material, and structural engineers the end product of which is a 5,400 square foot demonstration building for the U.S. Navy designed and built by architecture students at the Wood Materials Engineering Laboratory on the campus of Washington State University (Figures 1, 2). The project is a unique combination of design and science; it engages a series of experiments with new material development in the field of plastic wood composites, building envelope design and structural engineering. On the one hand, the project was an exploration into design possibilities inherent in engineered products such as wood-plastic composites, Oriented Strand Board (OSB), Laminated Veneer Lumber (LVL) and I-joists; on the other hand, the project was an exploration of the engineering potentials in these same materials. The building is possibly the first in the world to use wood-plastic composites so extensively and for such a wide variety of applications.     

炉渣混凝土保温复合砌块的设计与传热性能研究

墙体自保温材料是墙体材料革新和节能建筑的重点发展方向。通过对保温砌块规格、孔型和块型的综合分析,设计出一种炉渣混凝土保温复合墙体自保温材料,并重点分析和研究其热工性能。试验结果表明:炉渣的引入及聚苯板、加气混凝土的填入极大地改善了砌块的热工性能,三排孔填充聚苯板炉渣混凝土保温砌块的热阻可达1.13 m.2K/W,三排孔填充加气炉渣混凝土保温砌块的热阻可达0.83 m.2K/W。     

PS/NYC纳米复合材料的制备及阻燃性能

采用熔融加工法,以PS为基材、NYC为添加物制备NYC质量分数不同的PS/NYC纳米复合材料,测量其红外光谱、阻燃性能、拉伸强度、冲击强度、断裂伸长率、结晶和熔融行为。红外表征证实PS主链枝接上了NYC。NYC的加入使复合材料阻燃性能改善,发烟和滴落减少,氧指数增大,水平燃烧级别提高,冲击强度增大,但拉伸强度降低。PS与NYC兼容性稍差。     

基于PHOENICS的场地风环境优化——以某小学设计为例

场地风环境是绿色建筑设计中的重要内容,良好的风环境不仅能够改善建筑场地的舒适度,还能为室内的优质通风创造良好条件。在某小学的设计竞赛方案当中,通过前期对基地的区位、风环境参数、景观、道路、噪声条件的分析确定建筑体块关系即初步方案,利用Phoenics软件对初步方案的建筑体块进行风环境模拟,根据《绿色建筑评价标准》的要求找出风环境缺陷,对方案进行调整和优化设计直至使其满足风环境要求,从而得到风环境适宜的建筑体块,为下一步深入设计打好基础。     

Use of recycled demolition aggregate in precast products,phase II: Concrete paving blocks

A study undertaken at the University of Liverpool has investigated the potential for using construction and demolition waste (C&DW) as aggregate in the manufacture of a range of precast concrete products, i.e. building and paving blocks and pavement flags. Phase II, which is reported here, investigated concrete paving blocks. Recycled demolition aggregate can be used to replace newly quarried limestone aggregate, usually used in coarse (6 mm) and fine (4 mm-to-dust) gradings. The first objective, as was the case with concrete building blocks, was to replicate the process used by industry in fabricating concrete paving blocks in the laboratory. The compaction technique used involved vibration and pressure at the same time, i.e. a vibro-compaction technique. An electric hammer used previously for building blocks was not sufficient for adequate compaction of paving blocks. Adequate compaction could only be achieved by using the electric hammer while the specimens were on a vibrating table. The experimental work involved two main series of tests, i.e. paving blocks made with concrete- and masonry-derived aggregate. Variables that were investigated were level of replacement of (a) coarse aggregate only, (b) fine aggregate only, and (c) both coarse and fine aggregate. Investigation of mechanical properties, i.e. compressive and tensile splitting strength, of paving blocks made with recycled demolition aggregate determined levels of replacement which produced similar mechanical properties to paving blocks made with newly quarried aggregates. This had to be achieved without an increase in the cement content. The results from this research programme indicate that recycled demolition aggregate can be used for this new higher value market and therefore may encourage demolition contractors to develop crushing and screening facilities for this.