新型炭吸油材料的表征

为了解决环境污染中油污染的问题,世界各国相继投入大量的财力开发新型高效吸油材料.本研究针对多孔炭材料中膨胀石墨(EG)和植物炭疏水亲油的特点,分别以重油和20号柴油为吸附质,对膨胀石墨和炭化玉米秸秆、炭化油菜秸杆和炭化竹子3种植物炭的吸油特性和影响因素进行了详细的表征和研究.实验结果表明(1)蠕虫状膨胀石墨样品具有最大的吸油率,理想状态下可以达到80 kg/kg EG;(2)油类的粘度在很大程度上影响吸附速率,从而在很大程度上影响等温吸附曲线的形状;(3)膨胀石墨的循环再利用性能比较差;(4)3种代表性植物炭材料中,炭化玉米秸杆对20#柴油的吸附率最高,其次为炭化油菜秸秆,最小的是炭化竹子;(5)比表面积的改变,对液态吸附过程影响不大.     

TiO2负载工艺对膨胀石墨吸附原油性能的影响

将异丙醇钛盐与水洗后的可膨胀石墨，或者与水洗并干燥后的可膨胀石墨混合并加热，分别制备了负载TiO2的两种膨胀石墨吸附材料-膨胀石墨／TiO2-1（记为EG／TiO2-1）和膨胀石墨／TiO2-2（记为EG／TiO2-2）。结果表明：异丙醇钛盐与水洗后的可膨胀石墨混合后，部分TiO2溶胶存在于石墨层间；而与水洗并干燥后的可膨胀石墨混合后，绝大部分TiO2溶胶分布在石墨层表面及边缘。EG／TiO2-1和EG／TiO2-2对原油的最大吸附量分别为57g／g和55g／g。     

膨胀石墨／TiO2中原油的降解性能

以膨胀石墨（EG）为载体,钛酸丁酯为钛源,采用两种工艺制备了膨胀石墨／TiO2,产物分别记为EG／TiO2-1和EG／TiO2-2。XRD分析了产物的物相并确认TiOz已负载到膨胀石墨中。使用FT-IR光谱分析了被吸附原油的降解。结果表明：在紫外光（UV）照射下,吸附在纯EG、EG／TiO2-1和EG／TiO2-2中的原油均能被降解。原油在三种情况下降解程度顺序为：EG／Ti02-2〉EG／TiO2-1〉纯EG。     

膨胀石墨的表面修饰及其对甲醛吸附性能研究

以氧化插层法制备的膨胀石墨(expanded graphite,EG)为吸附剂,采用十六烷基三甲基溴化铵(cetyltrimethylammonium btomide,CTAB)对EG进行表面修饰(改性).研究改性和吸附工艺对EG吸附甲醛气体性能的影响.结果表明:改性荆的浓度对EG吸附甲醛气体有较大影响,当CTAB的浓度为0.04 mol/L时,改性EG对甲醛的吸附效果较好.随着改性温度和时间的增加,改性EG对甲醛的吸附量先增加后减少,最佳改性温度和时间分别为70℃和90min.在室温(25℃)下,改性EG对甲醛气体的吸附效果较好.最佳工艺条件下,改性EG对甲醛气体的吸附量高达840mg/g.     

抗氧化可膨胀石墨及其防火涂料的制备和性能

针对目前含硫可膨胀石墨(EG)抗氧化差等问题,采用最佳工艺:m(石墨)∶m(高氯酸)∶m(高锰酸钾)∶m(乙酸酐)=1∶1∶0.07∶(1～1.4),25℃,3h反应后,再用蔗糖硼酸脂溶液浸渍、脱水、60℃干燥,得到具有抗氧化无硫可膨胀石墨(Anti-O EG).对Anti-O EG的膨胀性能和添加Anti-O EG的防火涂料的防火隔热性能和炭质层微观结构形态进行了比较分析.结果表明,Anti-O EG在形成致密稳定的抗氧化膨胀炭质层和与聚磷酸铵/季戊四醇/三聚氰胺阻燃剂协同等方面具有突出的优点.     

高倍率膨胀石墨的制备及性能表征

以鳞片石墨(0.300mm)为原料,高锰酸钾为氧化剂,采用化学氧化和分步插层的制备工艺,乙酸辅助插层,高温膨胀制备具有低硫高倍率膨胀石墨(EG),探讨其最佳工艺条件并对其性能进行了表征。结果表明:石墨(g)∶硫酸(ml)∶高锰酸钾(g)=1.0∶6.0∶0.2,反应温度40℃,反应时间为90min;乙酸辅助插层时间为120min,抽滤洗涤至pH值为5~7,60℃干燥烘干可膨胀石墨,900℃下高温膨胀30s,即可得高倍率膨胀石墨;膨胀石墨的性能表征对研究其吸附行为和机理有重要意义。     

原位聚合法制备的聚醚醚酮/膨胀石墨复合材料及性能

以膨胀石墨(EG)负载对苯二酚后和4,4′-二氟二苯甲酮单体,采用原位亲核缩聚法制备了聚醚醚酮/膨胀石墨复合材料(PEEK/EG)。通过黏度分析法探讨了膨胀石墨对PEEK相对分子质量的影响;采用X射线衍射、差示扫描量热分析和热重分析研究了膨胀石墨对PEEK结晶性能和热性能的影响;通过扫描电镜表征了膨胀石墨在PEEK基体中的分散形态;通过摩擦测试仪研究了PEEK及PEEK/EG摩擦性能。结果表明,原位缩聚过程中引入EG不会影响PEEK晶型;EG含量为0.5%时PEEK/EG复合材料初始分解温度提高10℃,同时,EG在基体中分散效果良好。PEEK/EG-0.5%的磨损率为4.00×10-6 mm2/(N·m),远低于纯PEEK的15.80×10-6 mm2/(N·m)。     

淀粉膨胀石墨相变复合材料的制备及性能研究

介绍了一种利用的乳化机理制备淀粉膨胀石墨相变复合材料的方法。以石蜡、膨胀石墨(expanded graphite, EG)和淀粉为原材料,制备淀粉膨胀石墨相变复合材料,并对其性能进行研究。研究表明,红外光谱显示石蜡、EG和淀粉之间是物理结合,没有新物质生成。复合相变材料的储热能力随着相变材料的减少而降低。当EG掺量8.4%(质量分数)时,相变热逐渐减少,当EG掺量8.4%(质量分数)时,相变热急剧减少。相变复合材料热导率随着EG掺量的增加而增大。当EG掺量8.4%(质量分数)时,热导率逐渐增加。当EG掺量8.4%(质量分数)时,热导率增幅较小。EG的掺量为8.4%和11.0%(质量分数)时,扫描电镜显示淀粉膨胀石墨相变复合材料由许多微小的胶囊颗粒组成。相变材料被稳定的封装在微胶囊中,以防止在相变过程中发生泄露。综合考虑其储热性、导热性和稳定性,研究得到EG在复合相变材料中的最佳掺量为8.4%(质量分数)。     

膨胀石墨/硬脂酸复合相变材料的相变动力学

以硬脂酸(SA)为相变材料,以膨胀石墨(EG)为封装材料,采用熔融共混法制备了硬脂酸/膨胀石墨复合相变材料(SA/EG-PCMs)。采用多重率DSC、SEM、FT-IR、TG等方法对SA/EG-PCMs的结构和性能进行表征,应用非等温动力学数据处理模型进行了相变动力学研究。结果表明:EG具有大量网状结构的空洞(由10~50 mm厚的石墨片叠合而成的平行塌陷片层构成),通过表面吸附和微孔束缚对硬脂酸进行有效封装,使其颗粒粒径减小;根据相变动力学分析,EG对SA分子链段的热扩散运动具有限制作用,使SA/EG-PCMs的活化能均高于纯SA(E为535.55 k J/mol),热稳定性提高;且随着EG含量的提高SA/EG-PCMs的活化能逐渐增大,当EG含量(质量分数,下同)高于10%时EG对SA分子链端的阻碍作用加剧,使复合体系的相变温度和相变焓下降的幅度增大。     

膨胀石墨基复合相变材料的热稳定性研究

以膨胀石墨(EG)为载体材料,烷类(二十一烷、二十二烷)和脂肪酸类(正癸酸、硬脂酸)为相变材料,采用熔融共混法制备了不同类型膨胀石墨基复合相变材料,通过对其微观形貌、结构组成、热稳定性等表征测试,探究不同种类膨胀石墨基复合相变材料的热稳定性原理。结果表明,EG具有大量不同尺寸、结构和层次的微孔结构,是由10~50μm厚的石墨片叠合成的平行塌陷片层构成,具有良好的吸附性和稳定性,EG通过微孔束缚、氢键及表面极性等作用对相变材料进行物理吸附,使其热稳定性提高;随着EG含量的增加,烷类复合相变材料的热分解温度逐渐升高,分解速率减慢,脂肪酸类复合相变材料分解温度有所降低,分解速率减慢,但二者都在25~80℃间表现出良好的热循环稳定性,具有优良的热效率和热稳定性,满足中低温体系的温度调控要求。     

膨胀石墨的形貌结构与表面功能基团的XPS研究

膨胀石墨的孔结构和表面化学组成对其物化性能有着很大影响,利用扫描电镜（SEM）和X射线光电子能谱（XPS）对550～920℃制备的膨胀石墨形态结构和表面功能基团进行了表征,结果表明：在蠕虫状的膨胀石墨粒子表面和内部存在大量的网状孔洞,这些网络状孔洞是由10～50nm厚的石墨片叠合而成的平行塌陷片层构成;膨胀石墨表面化学组成以C、O元素为主,其它元素含量较低,其表面存在有-C=O、-C-O和-O-O-（过氧基团）等功能基团.     

Effect of ZnO loading technique on textural characteristic and methyl blue removal capacity of exfoliated graphite/ZnO composites

Two exfoliated graphite/ZnO composites, marked as EG/ZnO-1 and EG/ZnO-2, were prepared by heating a mixture of expandable graphite and Zn(OH)₂ or a mixture of expanded graphite (EG) and Zn(OH)₂, respectively. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption. Under UV irradiation, the composites were used for removing methyl blue (MB) from aqueous solution. For the composites made from expandable graphite (EG/ZnO-1), the micronsized ZnO particle agglomerates (1–20 μm) heterogeneously distributed at the surface of graphite flakes, while for the composites made from EG (EG/ZnO-2), the submicron-sized ZnO particle masses (0·2–0·5 μm) almost homogeneously located both at the surface and interior of graphite flakes. In the presence of UV irradiation, the composites had the adsorption capacity of EG and the photocatalysis capacity of ZnO at the same time. Compared with EG/ZnO-1, EG/ZnO-2 was more effective in removing MB. After 2 h of UV irradiation, MB could be completely removed by using the EG/ZnO-2 containing 45% ZnO, and the decomposition efficiency of the ZnO was the primary cause for the removal of MB.     

Electrochemical characterization of binderless, recompressed exfoliated graphite electrodes: electron-transfer kinetics and diffusion characteristics

Exfoliated graphite (EG) is prepared by the thermal exfoliation of graphite intercalation compounds at different temperatures. Surface and bulk physicochemical properties of EG are followed by spectroscopic and analytical methods and are observed to be a function of exfoliation temperature. EG particles can be recompressed without any binder and used as surface-renewable electrodes. Surface preparation is accomplished by either polishing or roughening the electrode surface using emery sheets. Effects of exfoliation temperature and the surface preparation on the electron-transfer kinetics and on the diffusion characteristics have been followed by electrochemical methods using several benchmark redox systems. It is found that the electron-transfer kinetics and the diffusion of K(4)[Fe(CN)(6)] are affected by the nature of the EG surface while that of iron(II)(1,10-phenanthroline)(3) and cobalt(II)(1,10-phenanthroline)(3) are not affected by the surface preparation. The redox systems are classified into different groups according to their kinetic sensitivity. Diffusion of electroactive species toward the EG electrodes is found to nonlinear. Current-time plots suggest that the recompressed EG electrodes can be modeled as fractals.     

重油在含有TiO2微粒的膨化石墨上的吸附和分解

将由天然鳞片石墨合成的层间化合物和异丙醇钛盐一起加热，成功地制得了具有光催化特性的锐钛矿粉TiO2分散在膨化石墨间的复合材料。一些具有球形结构的TiO2微粒，优先分散于石墨层的边沿。对重油而言，这种材料呈现了它在紫外（UV）光辐照下的吸附和分解作用。吸附在分散有TiO2的膨化石墨上的重油能在UV辐照下分解掉，其分角速度远比重油中混合锐钛矿结构的TiO2粒子的场合快速得多。     

可膨胀石墨阻燃半硬泡聚氨酯材料的性能

聚氨酯半硬质泡沫(SPUF)性能优异,应用广泛,但它属于易燃材料,且燃烧时极易产生烟毒,进而会对环境造成不利的影响。文中选用可膨胀石墨(EG)以及硅烷偶联剂KH791改性EG对全水发泡聚氨酯半硬泡进行阻燃,利用热重分析和残炭形貌对聚氨酯泡沫的热降解行为进行了研究,对比了EG改性前后对全水发泡聚氨酯半硬泡阻燃性能、热稳定性、力学性能和泡孔形貌的影响。结果表明,当EG的质量分数为20%时制得的可膨胀石墨阻燃聚氨酯泡沫氧指数可达29.4%,达到了UL94HB防火测试中HF-1级水平测试的要求;KH791改性EG后,阻燃效果略微降低,但是改性EG对于泡沫的泡孔形貌影响较小,能够提高全水发泡聚氨酯半硬泡的密度和压缩强度。     

Development of expanded graphite filled natural rubber vulcanizates in presence and absence of carbon black: Mechanical,thermal and morphological properties

As nanosized expanded graphite (EG) reveals a similar layered structure like organoclay and also it has a high expansion ratio so rubber chains can easily be intercalated into the gallery space. To improve the dispersion of EG in the rubber matrices, primarily the surface modification of the expanded graphite have been done and then the modified expanded graphite (MEG)/polar compatibilizer [epoxidized natural rubber (ENR)] master batch have been prepared by solution mixing method in the laboratory. After that the MEG/ENR master batch have been mixed with bulk natural rubber (NR) in presence and absence of carbon black (CB) in a laboratory scale open two roll mixing mill. Wide angle X-ray diffraction (WAXD) and high resolution transmission electron microscopic (HR-TEM) analysis of the nanocomposites revealed that MEG was intercalated and as well as delaminated in the NR matrix. Scanning electron microscope (SEM) images of the nanocomposites showed very rough surface than the pure NR matrix. In presence of expanded graphite the crack paths are channelized and coincide in one point suggesting the effect of plate like expanded graphite to acts as a barrier. We have got improved mechanical, thermal and dynamic mechanical properties for the MEG and MEG/CB loaded NR compounds compared to EG and EG/CB loaded NR compounds.     

Preparation and characterization of Nylon-6/exfoliated graphite composite via a combination method of in situ polymerization and thermal expansion

Nylon-6/exfoliated graphite (Nylon-6/EG) composite was prepared via a combination method of in situ polymerization and thermal expansion and characterized via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Otherwise, the resistivity value of Nylon-6/EG composite was measured, and the volume resistivity value was calculated as well as. The characterization showed that Nylon-6/EG composite had the morphology of the graphite worm and was structured by EG and Nylon-6, which covered on the surface of EG. The result exhibited that the volume resistivity of Nylon-6/EG composite would decrease when the dosage of EG increased. When the mass percent of EG was 1%, the the volume resistivity value of Nylon-6/EG composite could reach 2.3 × 10⁶ Ω cm. This shows that the combination method not only is very effective and reliable but also can play an important role in preparing antistatic Nylon-6 composite.     

膨胀石墨/聚酯导电复合材料的制备与导电行为

采用熔融共混法制备了膨胀石墨 ( EG) /聚酯 ( PET) 导电复合材料。利用扫描电镜及电导率测试等研究了复合材料的制备方法对其结构形态和导电性能的影响。结果表明, EG与聚合物基体间的相互作用和机械剪切力使PET分子能够进入EG的片层和孔隙中 , 促进了导电网络的形成, 导致EG/PET复合材料具有较低的逾渗值, 仅为3. 14 %。环氧树脂 ( ER) 与EG间的强相互作用使其易于对EG插层和剥离, 使ER-EG/PET体系的逾渗值进一步降低到1. 80 %。运用统计逾渗理论分析了材料的导电机制。发现复合材料电导率的各向异性、复杂的微观结构以及在高于逾渗值仍存在隧道导电是临界指数高于普适值的主要原因。