碳纳米管对中间相炭微球抗氧化性能的影响

通过原位热缩聚、模压成型、高温烧结制备了中间相炭微球/碳纳米管复合块体材料,采用热重分析和恒温氧化方法研究了碳纳米管对中间相炭微球抗氧化性能的影响。结果表明:原位添加适当比例的碳纳米管可以增强中间相炭微球的抗氧化性能。随着碳纳米管含量的增加,碳化处理后的炭材料微晶层间距变小,抗氧化性能增强;当添加5%碳纳米管时,样品初始失重温度提高了40℃,氧化10小时后质量损失仅为8.55%;但过多的碳纳米管会使微球粒径分布变宽,球形度变差,导致块体材料气孔率增加,降低了其抗氧化性能。     

中间相炭微球的二次生长

为考察中间相的形成和生长机理,将一种煤沥青制备的中间相炭微球添加到另一种沥青中进行二次热缩聚,结果发现中间相炭微球可以进行二次生长。二次热缩聚中间相炭微球的产率、粒径分布、表面和断面的形貌表明添加的中间相炭微球对于沥青热缩聚过程的物理作用更为主要;二次热缩聚过程包含了添加的中间相炭微球的二次生长过程和原料沥青独立成核生长两个相互竞争的过程,中间相炭微球的添加量对这两个过程有着重要的影响;中间相炭微球的生长是基本构筑单元不断进入相界面的构筑过程。     

添加松香对中间相炭微球制备的影响

以中温煤沥青为原料,松香为添加剂,通过热缩聚合法制备中间相炭微球。采用FT-IR、SEM、偏光显微镜等对所得产物进行表征,研究了松香对中间相炭微球制备的影响。研究表明松香的加入能有效限制沥青的过度聚合,不仅促进中间相炭微球的成核和生长,而且在很大程度上防止中间相炭微球的融并;当松香添加量为10%(质量分数)时,改性煤沥青经450℃热解2h可制备出球形度好、粒径均匀的中间相炭微球,其平均粒径为15.3μm,收率达44.1%。     

碳纳米管/中间相炭微球复合材料锂离子电池负极材料研究

采用热缩聚法(温度为420℃、反应时间为2 h)制备出碳纳米管/中间相炭微球复合材料。研究了碳纳米管添加量对中间相炭微球的形成和形貌的影响,以及对碳纳米管/中间相炭微球复合材料充放电性能的影响。实验结果表明,5%(质量分数)的碳纳米管添加量有利于中间相炭微球的形成,碳纳米管/中间相炭微球复合材料作为负极材料的锂离子电池充放电容量可达到337 mAh/g,20次循环后容量仍保持88%。     

中间相炭微球的制备及结构研究

以煤沥青为原料,采用热聚合的方法,在不同的保温时间下制备出中间相炭微球,通过SEM、激光粒度分析和XRD等分析手段对其表面形貌、粒径分布和微晶结构进行了分析,研究了聚合时间对其球形度、表面QI、粒径分布、微晶结构的影响.结果表明:随着保温时间的延长,中间相炭微球的球形度均较好,表面的QI减少,表面变得比较光滑,粒径分布变得比较集中,微晶结构也较好,当进一步延长保温时间,粒径分布又变得比较分散,微晶结构也变差.     

高密度石墨泡沫及其石蜡复合材料的热物理性能(英文)

以中间相沥青和添加中间相炭微球的沥青为原料,调整发泡压力和发泡温度制备沥青泡沫,经1273K炭化和2973K石墨化,制备了高密度石墨泡沫。为了进一步提高石墨泡沫的密度,采用573 K的沥青反复浸渍炭化未添加中间相炭微球的沥青在1273K下所制的泡沫炭,再经2973K石墨化获得增密度后的石墨泡沫。而后制备了相应石墨泡沫/石蜡复合材料。研究了石墨泡沫热物理性能的影响因素和石墨泡沫/石蜡复合材料的热行为。研究表明:沥青组分、发泡温度和发泡压力决定了石墨泡沫的结构和热物理性能,而石墨泡沫的热导率决定了复合材料的热行为。与石蜡相比,石墨泡沫/石蜡复合材料的热扩散系数提高了768至1588倍。石墨泡沫/石蜡复合材料的潜热与石蜡的质量分数成正比。该复合材料是快速响应电子散热材料的良好选择。     

原生QI成核中间相炭微球的结构

以含有原生ＱＩ的煤沥青为原料,采用热缩聚方法制备出中间相炭微球,用扫描电子显微镜（ＳＥＭ）观察了中间相炭微球的形貌和断面结构,经初步判断,在实验条件下原生ＱＩ成核煤沥青基中间相炭微球更倾向于“地球仪”型结构,并对以ＱＩ为核形成中间相微球的过程进行了分析。     

硅油/煤沥青乳液制备中间相炭微球

以中温煤沥青为原料,耐高温硅油为分散剂和导热介质,通过在反应釜中混合形成硅油/煤沥青乳液来制备中间相炭微球(Mesocarbon Microbeads,MCMB)。利用SEM、激光粒度仪和XRD分析等,研究了硅油用量对MCMB形成的影响。结果表明:硅油添加量对MCMB的形成有重要影响,当加入少量硅油后,MCMB粒径显著减小,分布均匀,小球表面较光滑,粘结现象减少,微晶结构得到改善,但四氢呋喃不溶物(THFI)收率降低。增加硅油用量,MCMB的粒径大小和微晶结构变化不大,小球之间粘结少,THFI收率增加,但小球表面附着小颗粒。当硅油/煤沥青的质量比为3∶1时,可得到粒径分布窄,D50为0.82μm,表面比较光滑,收率为8.2%的MCMB。     

添加对甲苯磺酸对中间相炭微球制备的影响

以中温煤沥青为原料,对甲苯磺酸为添加剂,在硅油分散体系中420℃热处理2h制备中间相炭微球,研究对甲苯磺酸用量对中间相炭微球形成的影响.利用SEM、FT-IR等方法对所得产物进行分析和表征,发现对甲苯磺酸对平面大分子芳烃的生成具有催化作用,能促进中间相炭微球的形成.在一定的热处理条件下,控制PTSA的用量,实现均相成核,能制备出球形度好、粒径均一的中间相球体.     

热缩聚工艺条件对中间相微球形成的影响

以煤焦油沥青为原料采用常压热缩聚工艺制备中间相沥青微球。考察了热缩聚温度和停留时间对中间相沥青收率、微球收率及形态的影响。发现在同一热缩聚温度下停留时间的延长，虽使中间相沥青的收率降低，但微球收率却相应提高，小球直径逐渐增大；提高热缩聚反应温度使微球更易长大，直到最终融并。通过控制热缩聚条件可以得到尺寸各异的中间相沥青微球。采用两步热溶抽提法可很好地将沥青微球从母液中提取出来     

炭化温度对中间相炭微球结构的影响

以煤沥青为原料,采用热聚合的方法,在不同的温度下制备出中间相炭微球(MCMB).通过SEM、激光粒径分析和XRD等分析手段对MCMB的表面形貌、粒径分布和微晶结构进行了分析.结果表明,随着温度的升高,MCMB的粒径变大,不同温度下制备的MCMB是由具有类似石墨结构的微晶组成的.420与450℃形成的MCMB微晶层间距d002较小,430与440℃形成的MCMB微晶层间距d002较大,随着温度的升高微晶宽度La变大.     

Interface enhancement of carbon nanotube/mesocarbon microbead isotropic composites

Carbon nanotubes (CNTs) are incorporated into mesocarbon microbead (MCMB)-derived isotropic graphite to improve their mechanical properties. CNTs are homogenously distributed on the MCMB surface by acid-treatment and mechanical mixing. The composites are prepared by cold isostatic pressing, carbonization, and graphitization. The mechanical properties and isotropy ratios of the CNT/MCMB composites are determined by four-point bend tests and thermal expansion measurements, respectively. The addition of CNTs improves the flexural strength by ca. 20%, while keeps a low isotropy ratio. CNTs dispersed on particle interfaces improve the interfacial strength, this reinforcing mechanism is confirmed by a fracture mode analysis with scanning electron microscope.     

Toughening modification of polycarbonate/poly(butylene terephthalate) blends achieved by simultaneous addition of elastomer particles and carbon nanotubes

Small quantities of maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MAH) copolymer and carbon nanotubes (CNTs) were introduced into polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends. The results demonstrated that simultaneously adding SEBS-g-MAH and CNTs greatly enhanced the fracture toughness of the samples and the impact strength increased with increasing CNT content. The morphologies, the dispersion of CNTs, the relaxation behaviors and the crystallization behaviors of samples were systematically investigated. SEBS-g-MAH formed the dispersed particles in the system. The particle diameter was decreased in the blend composites. CNTs exhibited homogeneous dispersion in the blend composites and they also formed a percolated network structure at relatively high content. The transesterification between PC and PBT components was suppressed by SEBS-g-MAH, and the crystallization ability of the PBT component was greatly enhanced. The toughening mechanisms were mainly related to the suppressed transesterification, the decreased elastomer particle size, and the formation of a CNT network structure.     

Mesocarbon microbeads supported PtSn catalysts for electrochemical oxidation of ethanol

Mesocarbon microbeads (MCMB) supported PtSn catalysts were prepared by alcohol reduction method and characterized by XRD, FESEM and EDX. XRD results show that the addition of Sn to Pt/MCMB extends the fcc lattice parameters of platinum and the particle size of PtSn/MCMB is about 2.6 nm, smaller than that of Pt/MCMB. The electrode catalytic activity in the electro-oxidation of ethanol was studied by cyclic voltammetry, Tafel plot, electrochemistry impedance spectra (EIS) and chronoamperometry. All the results showed that PtSn/MCMB gave higher catalytic activity for ethanol electro-oxidation than Pt/C (20 wt.% E-TEK).     

Improvement of the anode performance of graphite particles through surface modification in RF thermal plasma

Mesocarbon microbeads (MCMB) powders, which are known to be highly crystallized carbon materials and have a mean particle size of 11 μm, were treated in RF thermal plasma. Through the plasma treatment, the surface morphology, structure, and chemical composition of the powder were modified. The plasma-induced modification made the surface of MCMB particles disordered, and gave rise to an improvement in the thermal stability and electrochemical properties of the powders, such as the discharge capacity and first charge/discharge efficiency. It also made the powders suitable for further use as an anode in lithium-ion rechargeable batteries. Powders obtained without air exposure showed further improvement in anode performance.     

Synthesis of multi-walled carbon nanotube/silver nanocomposite powders by chemical reduction in aqueous solution

Carbon nanotube (CNT)/silver nanocomposite powders with different volume fractions of CNTs 2.5, 5 and 10?vol.% were prepared by chemical reduction in solution. Multi-walled CNTs underwent surface modifications for functionalisations by acid treatments. The acid-treated CNTs were investigated by FT-IR and X-ray photoelectron spectroscopy. The spectroscopic investigations of the acid-functionalised CNTs detected that several kinds of functional groups attached with the graphene structure as well as produced short and de-caped CNTs. Acidic stannous chloride solution was used to sensitise the surface of the functionalised CNTs. Silver was deposited on the surface of sensitised CNTs with chemical reduction reaction of alkaline silver nitrate solution by formaldehyde at room temperature and pH?～?9. The morphology of the produced CNT/silver nanocomposite powder was investigated by high-resolution SEM and TEM. It was observed that the produced CNT/silver nanocomposite powders have decorated type of spherical silver particle size 2–5?nm deposited on the surface of CNTs as well as the CNTs were implanted in large spherical silver nanoparticles of particle size ～200?nm. The chemical analysis of the produced powder indicates that some oxygen content is included in the prepared powders which can be reduced by heat treatment at temperatures between 300°C and 400°C under hydrogen atmosphere.     

Ce-Ti-O_x/CNTs复合粒子的制备及其对风化煤氧解的催化性能

以柠檬酸为螯合剂,以自制碳纳米管(CNTs)为载体,采用柠檬酸螯合沉积法制备了Ce-Ti-Ox/CNTs复合粒子,考察了柠檬酸的用量和乙二醇的添加对产物形貌的影响,采用TEM、XRD和FR-IR等手段对样品的形貌和晶相结构进行表征。结果表明,乙二醇的"桥接"作用有效地改善了负载效果及被负载的粒子均匀。探讨了复合金属氧化物的负载机理,并在此基础上研究了所得样品在风化煤硝酸氧解制备腐植酸中的催化性能,催化结果表明,Ce-Ti-Ox/CNTs复合粒子的催化性能明显优于单纯的CNTs、CeO2、TiO2、CeO2/CNTs以及TiO2/CNTs的催化性能,使腐殖酸的产率达到了65.43%。