碳纳米管超细粉碎分级的特性研究

为了制备超细碳纳米管粉体,利用机械磨和气流磨对碳纳米管粉体进行超细粉碎,通过调控设备运行时分级机和引风机的转速,对不同运行参数下制备的超细碳纳米管的粒度、能耗、形貌特征进行测试与分析。研究发现,常温下气流磨分级机转速在2 100～7 200 r/min时,所制备的碳纳米管细粉粒度d₅₀在10.127～2.540μm;高温（200℃）下气流磨转速在4 800～6 000 r/min时,所制备的碳纳米管细粉粒度d₅₀在5.061～2.831μm。机械磨风量在339.757～688.903 m³/h时,所制备的碳纳米管细粉粒度d₅₀在4.892～11.443μm。当粉碎到相同粒度d₅₀分别为5、10μm时,机械磨的产能分别为气流磨的1.6、2.1倍,而气流磨的单位吨能耗分别为机械磨的3、3.9倍。机械磨粉碎后的碳纳米管颗粒粒度明显减小,大多呈规则形状;气流磨粉碎后的碳纳米管颗粒粒径相对于机械磨粉碎后的颗粒粒度明显减小,大多呈无规则形状。因此,在工业生产中,综合考虑粉碎的粒度、能耗和形...     

Fe-Mo/MgO催化剂CVD法制备碳纳米管

研究了Fe-Mo／MgO催化剂裂解乙炔制备碳纳米管的反应条件。结果表明,反应气氛对碳纳米管的生长具有明显的影响,在Hz或Ar气氛下,所得碳纳米管的质量较差,而在N2-H2(1：1体积比)和Ar-H2(5．5：1体积比)气氛下乙炔裂解可制得纯度好、收率较高的碳纳米管。电镜观察发现在Ar-H2气氛下所制备碳纳米管的直径(平均直径为18nm)明显小于在N2-H2气氛下所制备碳纳米管(平均直径为30nm),这便于通过反应气氛的调节来控制碳纳米管的直径。用Fe-Mo／MgO做催化剂、乙炔为碳源,Ar-H2反应气氛下．850℃左右、反应30min所得碳纳米管的质量、产率最佳。     

静电纺丝参数对莫来石纤维制备的影响研究

采用静电纺丝法制备出莫来石纤维,考察了纺丝电压、纺丝液流速和针头直径对莫来石纤维物相及微观形貌的影响。结果表明:当纺丝电压为12 KV,纤维中除莫来石相外,还存有少量γ-Al2O3相,纤维直径较粗,纺丝电压为15KV时,纤维中全部为莫来石相,直径较均匀,纺丝电压增加到18 KV时,莫来石纤维直径分布变宽。随着纺丝流速由1.0m L/h增加到1.6 m L/h时,莫来石纤维直径分布逐渐变宽。当纺丝针头直径分别为0.6 mm、0.8 mm和1.2 mm,纤维逐渐变粗,纤维直径分别为132 nm、213 nm和240 nm。     

碳纳米管/聚苯胺复合材料的原位合成及其形成机理

用竖式炉流动法,以二茂铁为催化剂,硫为助催化剂,苯为碳源通过催化裂解反应在1100～1200℃制备了直线形多壁碳纳米管,碳纳米管外径为20～50nm,内径10～30nm,长度50～1000μm。在碳纳米管表面原位合成了聚苯胺,制备出碳纳米管/聚苯胺一维纳米复合材料,复合材料的直径为50～60nm。X射线衍射及热重分析表明,原位合成的聚苯胺的结晶程度和热稳定性较高,聚苯胺在碳纳米管表面以枝晶状生长,探讨了聚苯胺在碳纳米管表面的形成机理。     

生长温度及催化剂结构对碳纳米管形貌的影响

采用热CVD制备了图形化碳纳米管阵列薄膜。着重研究了生长温度、催化剂结构对碳纳米管形貌的影响。结果表明,当温度800℃时,生长的碳纳米管纯度较低;当温度为850℃时,生长为碳纤维;当生长温度为800℃时,生长纯度较好的碳纳米管,但碳纳米管垂直性较差。采用Al/Fe催化剂结构,生长出图形化的阵列化碳纳米管薄膜。     

生长温度及催化剂结构对碳纳米管形貌的影响

采用热CVD制备了图形化碳纳米管阵列薄膜。着重研究了生长温度、催化剂结构对碳纳米管形貌的影响。结果表明,当温度<800℃时,生长的碳纳米管纯度较低;当温度为850℃时,生长为碳纤维;当生长温度为800℃时,生长纯度较好的碳纳米管,但碳纳米管垂直性较差。采用Al/Fe催化剂结构,生长出图形化的阵列化碳纳米管薄膜。     

造纸废液喷雾干燥的工艺研究

为了解决造纸废液污染、有效利用废弃资源,以造纸废液为原料,采用喷雾干燥法制备木质素超细粉,在小试的基础上,对工业化制备条件及影响因素进行了讨论。确定出制备木质素超细粉的最佳工艺条件为:喷雾进料温度50—60℃、进料质量分数20%—25%、进风温度190℃、出风温度70℃、进料流量150 mL/m in、雾化压力2.3 MPa、喷嘴孔径0.8 mm,制得的木质素超细粉粒径为20—100 nm,比表面积37.8—455.6 m2/g。结果表明,采用喷雾干燥法处理造纸废液可得到木质素超细粉。     

火焰法制备碳纳米管研究进展

火焰法是近20年来兴起的一种新颖、高能效、低成本的碳纳米管制备方法。火焰法能同时提供制备碳纳米管所需的碳源和热源,具有大规模制备碳纳米管的潜力。由于火焰中环境极其复杂,控制火焰中碳纳米管的合成仍是巨大的挑战。本工作介绍了碳纳米管的结构及其性能,综述了扩散火焰(同轴扩散火焰、反扩散火焰和对冲扩散火焰)和预混火焰(单面滞止火焰和双面滞止火焰)制备碳纳米管的研究进展,并对碳纳米管的vapor–liquid–solid、顶部和底部及空心和实心生长机理作了简要阐述,介绍了本课题组基于甲烷/空气同轴射流火焰制备碳纳米管的研究进展。分析表明,金属镍起催化作用,催化剂颗粒包覆在碳纳米管内部,火焰合成的碳纳米管基于vapor–liquid–solid生长机制,碳纳米管直径为50~90 nm,平均直径为65 nm。对火焰法制备碳纳米管的发展方向进行了展望。     

聚酰胺纤维

<正>20142045流量对静电纺尼龙6纳米纤维形态和沉降区的影响Zargham Shamim…;Journal of Engineered Fibersand Fabrics,2012,7(4),p.42(英)静电纺丝是一种制备连续聚合物纤维的工艺,它可制备出直径为纳米级的纤维。将尼龙6溶解在甲酸中,采用静电纺工艺制得纳米纤维。以施加电压20 kV,纺丝距离15 cm,纺丝液流量分别为0.1 mL/h、0.5 mL/h、1 mL/h和1.5 mL/h,溶液质量分数为20%的条件制备直径不同的纤维。纺丝液流量对纤维的直径分布、液滴的大小、液滴在毛细管     

环氧树脂/氟化碳纳米管复合材料的制备与性能

本文用聚四氟乙烯对碳纳米管进行氟化改性,制备了氟化碳纳米管,并采用超声分散法和模具浇注法制备了氟化碳纳米管/环氧树脂复合材料。采用红外光谱（FTIR）、X射线衍射（XRD）对氟化碳纳米管进行了表征,并利用透射电镜（TEM）观察了氟化碳纳米管在丙酮中的分散情况。结果表明：在碳纳米管表面生成了C-F键,成功地制备了氟化碳纳米管,使碳纳米管之间的缠结团聚现象得到明显改善,提高了碳纳米管在有机溶剂中的分散性。研究了不同含量的氟化碳纳米管对氟化碳纳米管/环氧树脂复合材料的冲击性能、弯曲性能的影响。研究表明,当MWCNT含量为1.5wt%时,材料的冲击强度和弯曲强度最高,分别为25.85 kJ/m2、128.1MPa。     

碳包铁颗粒和放射状碳纳米管微观结构的研究

以苯和甲苯为碳源，二茂铁为催化剂前驱体，含硫化合物为助催化剂，采用竖式炉流动催化法，通过减小载人的氢气量以改变催化剂颗粒的状态及反应条件，获得了碳包铁颗粒以及放射状碳纳米管，运用TEM和HRTEM对其形貌和结构进行了分析，并初步探讨了其生长机理。结果表明，在碳源、催化剂和炉温分布相同的条件下，氢气量为5400mL／min时形成直线型和弯曲型两种不同形态的碳纳米管，后者管径大于前者。氢气量为2000mL／min时，产物90％以上为碳包铁颗粒，其平均直径约为530nm，其中还有少量放射状碳纳米管，其外径为45—50nm，内径为3—5nm，管径较为均匀。     

Counting Efficiency of the TSI Model 3020 Condensation Nucleus Counter

The counting efficiency of the TSI model 3020 condensation nucleus counter (CNC) was determined as a function of aerosol flow rate and trigger level using aerosols of known size and an aerosol electrometer. When the aerosol flow rate dropped from 300 to 200 mL/min, counting efficiencies increased significantly in the single-particle counting mode for particles with diameter < 20 nm while those for larger particles remained constant. However, the photometric mode counting efficiency for particles with diameter > 20 nm increased and exceeded unity. When the aerosol flow rate was reduced to 100 mL/min, the counting efficiencies for both counting modes decreased regardless of particle size. Varying the trigger level of the CNC did not influence the photometric mode counting efficiency. However, the counting efficiency of the single-particle counting mode increased with decreasing trigger level, especially for particles < 20 nm in diameter. Characteristics for individual instruments need to be measured because counting efficiencies of two CNCs with the same trigger level and flow rate were not identical.     

活性炭负载TiO2的制备与表征

在固定床中以玉米秸秆为原料采用二氧化碳活化制备活性炭,并以活性炭为载体,采用溶胶-凝胶法制备纳米TiO2／AC复合催化剂,通过光催化降解甲基橙对其光催化活性进行研究。正交实验表明：当二氧化碳流量500mL·min^-1、活化温度800℃、活化时间40min时,制备的活性炭负载TiO2光催化性能最好,甲基橙降解率高达98．4％;采用XRD和SEM表征最佳工艺制得的TiO2／AC,发现TiO2／AC为锐钛矿型,粒径约为12nm。     

等离子体裂解天然气制纳米炭黑和乙炔

利用200kW的中试装置,在常压下研究了天然气在氮热等离子体中的裂解行为,考察了输入功率、甲烷流量以及CH4/N2摩尔比对反应的影响。结果表明:天然气在氮热等离子体中发生了强烈的分解反应,生成大量炭黑和C2烃;CH4/N2摩尔比为0.4,输入功率120kW时,炭黑的收率为42.0%,甲烷的最大转化率为97.1%;所制得的炭黑平均粒径38nm,分布范围狭窄,炭黑的DBP吸收值1.40mL/g,是一种高结构性炭黑;红外光谱分析发现炭黑中存在芳香C—C键及大量氮基官能团如—NH、—CN等,以及—CH,—OH,—COOH等。     

Production of carbon molecular sieves from palm shell based activated carbon by pore sizes modification with benzene for methane selective separation

Palm shell based activated carbon prepared by K₂CO₃ activation is used as precursor in the production of carbon molecular sieve by chemical vapor deposition (CVD) method using benzene as depositing agent. The influences of deposition temperature, time, and flow rate of benzene on pore development of carbon molecular sieve (CMS) and methane (CH₄) adsorption capacity were investigated. The parameters that varied are the deposition temperature range of 600 to 1000 °C, time from 5.0 to 60 min, and benzene flow rate from 3.0 to 15 mL/min. The results show that in all cases, increasing the deposition temperature, time, and flow rate of benzene result in a decrease in adsorption capacity of N₂, pore volume and pore diameter of CMS. The BET surface area of CMS (approximately 1065 m²/g) and the adsorption capacity of CH₄ were at a maximum value at a deposition temperature of 800 °C, time of 20 min and benzene flow rate of 6 mL/min. The product has a good selectivity for separating CH₄ from carbon dioxide (CO₂), nitrogen (N₂), and oxygen (O₂).     

气相色谱测定消心痛中有机溶剂的残留量

建立了C．C测定消心痛原料药中氯仿、乙酸、乙酸乙酯残留量的方法。采用色谱柱为PEG-20M不锈钢柱(4m×2mm),柱温采用程序升高,起始柱温50℃维持3 min,然后以10℃/min的速率升至180℃维持5 min,再以10℃/min的速率升至280℃维持10 min。FID检测器,检测器温度320℃,进样口温度320℃,氮气为载气,流速50mL/min,氢气流速30 mL/min。空气流速400 mL/min。可使三种有机溶剂完全分离,氯仿在0．0005～0．003 mg/mL的浓度范围内呈良好的线性关系(r=0．9994),回收率为100．3％(RSD＜1．0％)；乙酸乙酯在0．005～0．03 mg/mL的浓度范围内呈良好的线性关系(r=0．9999),回收率为100．5％,(RSD＜1．0％)；乙酸在0．005～0．03 mg/mL的浓度范围内呈良好的线性关系(r=0．9997),回收率为98．7％,(RSD＜1．0％)。     

Preparation and characterization of polydiphenylamine/multi‐walled carbon nanotube composites

We describe the synthesis of methane sulfonic acid (MeSA)‐doped poly(diphenylamine) (PDPA) with carboxylic groups containing multi‐walled carbon nanotubes (c‐MWNTs) via in situ polymerization. Diphenylamine monomers were adsorbed on to the surface of c‐MWNTs and polymerized to form PDPA/c‐MWNT composites. SEM and TEM images indicated two different types of materials: the thinner fibrous phase and the larger globular phase. The individual fibrous phase had a diameter around 100–130 nm, which should be the carbon nanotubes (diameter 20–30 nm) coated with a PDPA layer. The structure of PDPA/c‐MWNT composites was characterized by FTIR, UV‐visible spectroscopy and X‐ray diffraction patterns. The electrical conductivities of PDPA/c‐MWNT composites were much higher than that of PDPA without c‐MWNTs. Copyright © 2006 Society of Chemical Industry     

Synthesis of silica nanoparticles in a continuous-flow microwave reactor

Monodispersed silica colloidal spherical nanoparticles were synthesized from the hydrolysis and condensation of tetraethylorthosilicate (TEOS) by using a continuous microwave synthesis process. The flow rate was varied from 43 to 101 mL/min in order to establish the optimum conditions required to obtain unagglomerated silica nanopowders. The results were compared with those obtained in batch systems. In particular the mean particle diameter became smaller than 50 nm as the residence time was decreased by increasing the flow rate to 101 mL/min.     

Enhancement of Extrinsic Charging Efficiency of a Nanoparticle Charger with Multiple Discharging Wires

A unipolar charger with multiple discharging wires has been developed and investigated to enhance the extrinsic charging efficiency of nanoparticles by using sheath air near the wall of the charger. The applied voltage of the charger ranged from +4.0 to +10 kV, corresponding to corona current from 0.02 to 119.63 μA. Monodisperse NaCl particles of 10 ～ 50 nm and Ag particles of 2.5 ～ 10 nm in diameter were produced to test the performance of the charger with multiple discharging wires and to investigate the particle loss at different sheath flow rates, corona voltages and sheath air velocities. Results showed that the optimal efficiency in the charger was obtained at +9 kV applied voltage, 10 L/min aerosol flow rate and 20 L/min sheath air flow rate. The extrinsic charging efficiency increased from 2.86% to 86.3% in the charger as the particle diameter increasing from 2.5 to 50 nm. The TDMA (tandem-differential mobility analyzer) technique was used to investigate the charge distribution, and the charge distributions in the exit were obtained at the optimal operating condition.     

Development,optimization, and characterization of electrospun poly(lactic acid) nanofibers containing multi‐walled carbon nanotubes

Electrospinning of poly (L ‐D ‐lactic acid) (PLA) was investigated with the addition of multi‐walled carbon nanotubes (MWNT) for development of a scaffold for tissue engineering. Through this experiment, it was determined that the optimal concentration of PLA with weight average molecular weight (M_w) 250,000 g/mol is ～20 wt % as indicated by scanning electron microscopy. This concentration produces fibers with no beading or film formation. The preferred solvent system is a combination of chloroform and dimethyl formamide to alleviate the volatile action of chloroform. The optimum processing parameters for PLA are an electric field of 1 kV/cm which was determined by a surface response plot to minimize fiber diameter based on the applied voltage, working distance, and addition of MWNT. Fourier Transform infrared spectroscopy has indicated the removal of the solvent system. With the addition of MWNT, the fiber diameter was drastically reduced by 70% to form fibers with a mean diameter of 700 nm. This is believed to be due to an increased surface charge density for the MWNT/polymer solution. Transmission electron microscopy validated the alignment of the MWNT within the fibers. MWNT loading exhibited an increase in the conductance of the scaffold and the tensile modulus at an optimal loading level of 0.25 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007