现代仪器分析技术在炭材料研究中的应用

着重就热分析法、红外光谱分析和激光Raman光谱法研究炭材料的反应机理、催化剂的催化性能、炭材料的结构及性质等方面的应用情况作了综述。     

炭材料热分析技术概述

论述了TG,DTA,DTG,DSC和DMTA等热分析技术在炭及其复合材料上的应用。TG-DTG技术可以追踪升温过程的质量变化,直接体现着材料的高温抗氧化性能、热稳定性,并可确定材料的燃点等;热效应曲线则反映出材料升温分解过程中的放热或吸热效应,是和材料组成及结构变化密切相关的,二者结合,从结构本质上探析了炭材料的物理化学反应机制。因此,TG-DTG,DTA,DSC技术被广泛应用于炭材料的反应机理、催化剂的催化机制、高温抗氧化性、耐热性、活性炭的表面性能、燃烧特性等的探究;DMTA技术是研究高聚物结构-分子运动-性能的一种有效手段,被用于测定炭材料界面性能。     

磷酸盐浸渍泡沫炭的抗氧化性能研究

泡沫炭材料具有轻质、高比强度及独特的热性能.将在1200℃下炭化后的煤基泡沫炭在真空度为-0.1MPa下,用磷酸-磷酸盐的混合溶液进行浸渍,并经900℃固化2h制成高热稳定性的泡沫炭材料.利用热重分析仪(TG)及在空气中700℃下煅烧1h的方法研究了泡沫炭浸渍前后的抗氧化性能变化情况.通过扫描电子显微镜(SEM)和红外光谱(FT-IR)探讨了抗氧化涂层的结构变化及其抗氧化机理.实验结果表明:采用磷酸盐溶液浸渍泡沫炭可在其表面形成均匀致密的玻璃态涂层,使泡沫炭的抗氧化性能有了明显的提高,扩展了泡沫炭材料在高温工程领域中应用范围.     

三嗪膨胀阻燃聚乳酸的制备及其性能

将实验室自制的三嗪大分子成炭发泡剂(CFA)、聚磷酸铵(APP)及硅树脂复配成膨胀阻燃剂(IFR)添加到聚乳酸(PLA)材料中制备阻燃PLA(IFR-PLA)材料,通过极限氧指数(LOI)和垂直燃烧(UL-94)测试研究了材料的阻燃性能。通过热重分析(TGA)测试研究了材料的热降解行为和成炭性能,通过锥形量热(CONE)测试研究了材料的燃烧行为,并对其燃烧后残炭的形貌进行研究。结果表明:当APP与CFA的质量比为5∶1,IFR的添加量为15%时,IFR-PLA材料通过UL-94 V-0级,LOI值达33.5%。IFR的加入促进了PLA材料的降解和成炭,从而提高了材料的阻燃性能。     

CuO微胶囊处理ABS的锥形量热及热解

采用热重分析和锥形量热分析研究添加CuO微胶囊阻燃剂的丙烯腈-丁二烯-苯乙烯共聚物(Acrylonitrile- Butadiene-Styrene, ABS)的热解和阻燃性能,并用Broido方程计算ABS的动力学参数热解活化能的变化. 结果发现,添加CuO微胶囊的ABS热量释放、烟气、CO和CO2排放等参数降低,表明CuO微胶囊对ABS具有较好的阻燃、抑烟效果. 添加CuO微胶囊的ABS热解反应表观活化能升高21 kJ/mol,表明CuO微胶囊提高了ABS的热稳定性,使材料热解困难;同时其剩炭量提高27.2%,表明CuO微胶囊具有催化成炭、减少可燃性气体的作用.     

MnO2对MPP/PEPA阻燃PP性能的影响

采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂以及MnO2为阻燃增效剂,制备了具有良好阻燃性能的无卤阻燃聚丙烯(PP),研究了MnO2用量对PP阻燃和力学性能的影响.结果表明,添加少量的MnO2即可显著提高材料的阻燃性能;当MPP,PEPA,MnO2添加质量分数分别为12%,8%和2%时,材料的氧指数(LOI)高达32.0%,并具有较好的力学性能.Kissinger动力学分析结果表明,添加MnO2可以催化MPP/PEPA问的酯化反应,改变材料的热降解途径.扫描电子显微镜(SEM)和热重分析(TGA)表明,MnO2可以起到稳定炭层,促进成炭、增加炭层厚度作用.     

Na型Y沸石为模板制备多孔炭材料的研究

以Na型Y沸石分子筛为模板,糠醇为碳源,制备了微孔模板炭材料.用热重分析研究了样品的热重行为,用N<,2>吸附表征了样品的比表面积和孔结构特征.研究表明,采用此方法得到了比表面积最大为826 m<'2>/g的模板炭材料,且孔径均一,分布主要集中在1.1 nm和1.6 nm.     

新型低卤阻燃PS-HI材料的制备与性能

采用新型阻燃成炭剂,经过熔融共混技术制备低卤阻燃高抗冲聚苯乙烯(PS-HI)材料。通过锥形量热、垂直燃烧、力学性能分析,热重分析和扫描电子显微镜等测试方法,研究了低卤阻燃PS-HI材料的综合性能。结果表明,新型低卤阻燃PS-HI材料气相阻燃作用明显,具有较低的密度,较好的热稳定性,较好的耐腐蚀性,较好的耐热蠕变性能,阻燃性能稳定,同时该材料具有优异的力学性能和加工性能。     

热重分析用于测试烧蚀材料

介绍了四种聚合物和五种酚醛树脂在氮气中的热重分析结果，同时介绍了采用改性酚醛树脂的五种烧蚀试样的热重分析结果。说明了热重分析在表征烧蚀材料及其原料的热失重过程、结炭率及聚合物主链断裂分解活化能方面的应用。     

沥青基泡沫炭的工艺制备及应用概述

泡沫炭是一种具有大尺寸孔径的网状功能型新型炭材料,具有密度小、强度高、导电、导热、热稳定、化学稳定等良好的物理和化学性能,已引起人们的广泛关注。本文综述了泡沫炭的发展历史、沥青基泡沫炭的制备方法及工艺影响,以及在电磁、热性能、结构材料、生物医药、过滤材料等方面的应用研究,并展望了沥青基泡沫炭的研究前景。     

碳纳米管及C60和石墨氧化动力学机理函数的分析

The oxidation of carbon nanotubes, C60 and graphite was studied by thermogravimetric (TG) analysis and differential thermal analysis (DTA) technique, and the oxidation kinetic models of three carbon materials studied were analyzed by mechanism-function method. The results indicate that three carbon species adopt different oxidation mechanisms due to their different structures. The oxidation of carbon nanotubes with cylindrical structure follows contracting volume reaction mechanism [R3 mechanism, 1 - (1 -α)1/3 = kt], indicating that the oxidation of carbon nanotubes takes place from the ends to the center. For graphite with planar sandwich structure, the oxidation starts at the edges initially and gradually moves toward the center, which corresponds to contracting area phase boundary reaction mechanism [R2 mechanism, 1 - (1 - α)1/2 = κt]. The oxidation of C60 with spherical structure,however, is complex and apparently cannot be illustrated with a single kinetic model. The values of apparent activation energy for C60 determined using Kissing method is 91kJ·mol-1.     

Effect of additives on the decomposition of KClO4

The effect of the addition of carbon and/or sulphur on potassium perchlorate (KClO₄) decomposition has been studied by thermo-analytical techniques, i.e. thermogravimetric analysis (TGA), differential thermogravimetric analysis (DTGA), differential scanning calorimetry (d.s.c.) and Fourier transform infrared (FT-i.r.) spectroscopy. The TGA, DTGA and d.s.c. results show that carbon catalyses the decomposition of KClO₄, and simultaneous decomposition of KClO₄ and oxidation of carbon takes place in a solid phase. Addition of sulphur to KClO₄ does not show any major effect but its presence in a ternary mixture (KClO₄, carbon and sulphur) facilitates the decomposition/oxidation reaction. The FT-i.r. emission studies show that CO₂ and SO₂ are the major combustion products detectable by infrared spectroscopy.     

碳点/水性聚氨酯复合材料的制备及性能

以异氟尔酮二异氰酸酯(IPDI)和聚氧化丙烯二醇(PPG)为原料制备水性聚氨酯,以此为碳源,采用水热法制备碳点,再以IPDI和聚己二酸-1,4-丁二醇酯二醇(PBA)为原料,将不同质量分数的碳点加入反应体系中,制得碳点/水性聚氨酯复合材料。采用FTIR、TEM、SEM、TGA、DSC、UV-Vis、荧光光谱以及力学性能测试等对复合材料结构和性能进行检测和表征。结果显示,复合胶膜的热稳定性、荧光性能、力学强度都因碳点的加入得到提高,当碳点加入质量分数达0.5%时,复合胶膜的量子产率和荧光寿命分别为4.15%和2.43 ns,胶膜的拉伸强度和断裂伸长率分别为36.80 MPa和660%,比未加碳点的样品分别提高了29.7%和33.3%。     

磺酸化碳材料负载Ru催化剂催化纤维素水解/加氢反应

采用纤维素衍生碳、活性炭和介孔碳材料CMK-3为不同碳源前驱体,在不同磺酸化条件下制备磺酸化碳材料负载Ru的双功能催化剂,并用FTIR光谱、XRD、元素分析、热重分析、N₂物理吸附 脱附进行了表征,考察了其对纤维素加氢反应的催化活性。结果表明：相比于纤维素衍生化碳,活性炭和介孔碳CMK-3为碳源经过磺酸化后制备的催化剂具有较强的结合-SO₃H的能力和较高的催化活性,对多元醇具有良好的选择性,170 ℃下反应10 h六元醇的收率可高达84.0%。在循环使用时,磺酸化活性炭负载Ru催化剂催化活性有所降低,但可以保持对多元醇的选择性;而磺酸化介孔碳负载Ru催化剂存在少量S流失,转化率基本不变,但产物的选择性有所降低。     

离子液体自模板合成多孔碳氮材料及其对二氧化碳的吸附

以多种氰基离子液体为前驱体，采用高温碳化法直接制备多孔碳氮材料，系统考察了离子液体前驱体阳离子结构、阴离子种类及合成条件等因素对碳化材料比表面积、氮元素含量及氮种类的影响，并研究其对CO2的吸附性能。结果表明，阴离子在聚合过程中起模板剂的作用。合成材料主要呈介孔结构，比表面积最高达732.6 m2/g，氮含量最高为9.9wt%，在温度25℃、压力1.8 MPa条件下，CO2的吸附量最高达20.9wt%。多孔碳氮材料经180℃真空加热后可完全脱附再生，再生稳定性良好。     

Synthesis and characterization of microporous carbons templated by ammonium-form zeolite Y

Emerging applications such as gas storage require porous carbon materials with tailored structural and surface properties. Template synthesis approach to porous carbons offers opportunities for tailoring these properties. In this study, ammonium-form zeolite Y (NH₄Y) was used as a template and furfuryl alcohol (FA) was employed as a carbon precursor to prepare microporous carbons by simple impregnation method. The effects of synthesis conditions such as carbonization temperatures and heating rates on the pore structure of the microporous carbons were investigated. The thermal behaviors of FA-NH₄Y mixtures and zeolite/carbon composites were studied by thermogravimetric analysis (TGA). The physical, structural, and surface properties of the microporous carbons were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), elemental analysis, and physical adsorption of nitrogen. Microporous carbons with high surface areas, pore volumes and nitrogen-containing surface functional groups can be readily synthesized.     

Effect of polymer chain length on the solubility of polystyrene grafted single‐walled carbon nanotubes in tetrahydrofuran

BACKGROUND: While carbon nanotubes are highly interesting materials for a variety of applications, their inherent insolubility limits widespread applications and solution‐phase processing. It is known that chemical functionalization can overcome this insolubility problem, and covalent grafting of polymers to the nanotube surface has been shown to be effective. In this study, the effect of polymer molecular weight on the solubility of polymer–nanotube conjugates was investigated. RESULTS: A series of nitroxide‐capped polystyrene polymers ranging in molecular weight from 2900 to 105 000 g mol^?1 were grafted to single‐walled carbon nanotubes (SWNTs). The resulting polystyrene–SWNT conjugates exhibited different degrees of solubility in tetrahydrofuran. Subsequent thermogravimetric and UV‐visible spectroscopy analyses indicated that carbon nanotube solubility reached a maximum when a polymer sample with a weight‐average molecular weight of 10 000 g mol^?1 was used. Higher and lower molecular weights resulted in reduced solubilities. CONCLUSION: Polymer chains of intermediate length maximize SWNT solubility, while lengths that are too low or too high seem to diminish the ability of the polymer–SWNT conjugates to remain in solution. Copyright © 2008 Society of Chemical Industry     

Thermal transport and chemical conversion in single reacting sorbent particles

The effects of particle size and carbon dioxide concentration on chemical conversion in engineered spherical particles undergoing calcium oxide looping are investigated. Particles are thermochemically cycled in a furnace under different carbon dioxide concentrations. Changes in composition due to chemical reactions are measured using thermogravimetric analysis. Gas composition at the furnace exit is evaluated with mass spectroscopy. A numerical model of thermal transport phenomena developed previously is adapted to match the physical system investigated in the present study. The model is used to elucidate effects of reacting medium characteristics on particle temperature and reaction extent. Experimental and numerical results show that (1) an increase in particle size results in a decrease in carbonation extent, and (2) the carbonation step consists of fast and slow reaction regimes. The reaction rates in the fast and slow carbonation regimes increase with increasing carbon dioxide concentration. The effect of carbon dioxide concentration and the distinction between the fast and slow regimes become more pronounced with increasing particle size.     

两种煤沥青的浸渍性能分析

采用热重／差热分析、核磁共振、热台显微镜在位观察等方法,对太钢改质沥青和北京焦化厂中温煤沥青的软化点、元素组成、结构、组成、粘度进行了分析,以评价其作为浸渍沥青的性能。结果表明：太钢改质沥青比北京焦化厂中温煤沥青的吡啶不溶物含量高,芳香度低,高温流动性略好,产碳率也高。     

炭吸附纳米氧化锌的制备及其光催化性能研究

以粗氧化锌和冰乙酸为原料,采用炭吸附水热法制备纳米氧化锌粉体。通过热重/差热仪（TG-DTA）、X射线衍射仪（XRD）、透射电镜（TEM）和紫外可见光谱仪（UV-Vis）等对所得催化剂的焙烧温度、物相、微粒尺寸及光吸收性能进行表征。结果表明：炭黑的吸附有效阻止了纳米氧化锌在制备、干燥以及焙烧过程的团聚和烧结,600 ℃焙烧制备的催化剂颗粒均匀,分散性好,团聚较少,平均晶粒尺寸为20 nm,比表面积约为85.25 m2/g。纳米氧化锌作光催化剂对甲基橙进行光催化降解,在60 min内降解率为97%。