对甲基苯甲醛改性煤沥青的原位成纤机理研究

以对甲基苯甲醛为改性剂,在对甲苯磺酸的作用下对煤沥青进行了改性,并对改性后煤沥青的原位成纤机制进行研究。采用FT IR和1H NMR对改性煤沥青的化学结构进行分析,采用SEM对改性煤沥青的原位成纤形态进行观察。研究表明,对甲基苯甲醛能够与煤沥青发生亲电取代反应,使煤沥青中的活性小分子交联形成大分子。此外,改性煤沥青中出现很多微纤,随着改性时间的增加,纤维直径越来越大,最后形成分布均匀且线性很好的纤维束。因此,经过对甲基苯甲醛改性后的煤沥青有望成为优质的炭材料基体前躯体。     

改性纳米氧化锌对煤沥青延伸性能的影响

利用纳米氧化锌对煤沥青进行改性研究,考查了改性温度,分散方式,纳米氧化锌的添加量对煤沥青延伸性能的影响,优化了煤沥青的改性工艺,并对煤沥青的改性原理进行了探讨。     

电场对改性煤沥青中间相形成的影响

在氮气保护和高压电场作用下,以中温煤沥青为原料,采用带程序升温的管式炉进行热转化实验,制备出煤沥青中间相。采用偏光显微镜、X射线衍射仪(XRD)、红外光谱仪(FT-IR)和热重分析仪(TG)等测试手段对其形貌和结构进行了分析表征。研究了原料改性和电场对煤沥青中间相形成的影响。研究结果表明,原料改性对中间相的形成有促进作用。电场强度控制在20kV/m,在420℃开始引入电场,有利于生成具有各向异性的中间相组织。     

煤焦油沥青制备中间相

煤焦油沥青在微型高压釜中、氮气氛下,通过改变反应温度和停留时间,制取了中间相沥青(MP)。采用FTIR、偏光显微镜、XRD和SEM对MP进行了表征,表明煤焦油沥青经脱氢缩合反应转变成MP。其最佳反应条件为400℃、7h。     

石油沥青对煤焦油沥青焦结构和电性能的影响

为了研究石油沥青(PP)作为煤沥青添加剂对沥青焦结构及导电性能的影响,将精制煤沥青(RCTP)与PP混合共炭化,同时在机械搅拌的作用下制焦,并对共炭化过程中PP和机械作用产生的影响机理进行了探讨和分析.采用偏光显微镜、X射线衍射仪、热重分析仪、比表面分析仪对所制半焦的结构进行了分析,利用电化学石英晶体微天平及电阻率仪对所制针状焦的性能进行了考察.结果表明:当PP质量分数为10%、搅拌速率为100 r/min、以间歇搅拌方式所制针状焦,其纤维组织占比达到了67.9%,电阻率降为676Ω·mm~2/m,即PP和机械搅拌二者联合作用存在下可显著增加中间相各向异性组织和纤维组织的含量,有利于改善半焦结构,使其结构更加趋于有序,所得针状焦电阻率也得到明显降低.     

原位催化热解煤沥青生长毫米级多壁碳纳米管

本文提出一种以煤沥青(CTP)为碳源,乙酸镍为催化剂前驱体,简单通用的多壁碳纳米管(MWCNTs)催化热解生长工艺.借助SEM、TEM、Raman及TGA等分析手段对样品微观形貌结构、缺陷度及含量进行表征,系统探索了温度、催化剂用量及生长时间对MWCNTs含量、晶体缺陷、长径比的影响规律.结果 表明:Ni催化生长的MWCNTs壁厚约10 nm,管径几十纳米;850～1000℃范围内,随温度升高,拉曼光谱中D1峰和G峰强度比(ID1/IG)由0.95减小到0.92再增大到1.02;热重测试DTG拟合分析表明CNTs和无定型碳含量的峰面积比S2/S1比值变化也有类似趋势;当Ni的质量分数为0 ～0.75％,MWCNTs随Ni含量的增加而增多;延长热解时间有利于MWCNTs生长,950℃,0.75％ Ni时,催化热解CTP 3 h制备的MWCNTs长度可达毫米级.在综合分析和TEM表征基础上,认为CTP催化热解生长MWCNTs时,为顶端和底端机理并存过程.     

呋喃树脂对煤沥青流变性能的影响

采用旋转黏度计测定了含有不同比例呋喃树脂的煤沥青的表观黏度。考察了呋喃树脂对煤沥青表观黏度、残炭率及软化点的影响。同时，采用扫描电镜(SEM)研究了添加呋喃树脂后煤沥青的表面形貌。结果表明，添加质量分数为3．6％～9．0％的呋喃树脂使煤沥青在达到相同黏度值时温度下降5℃～15℃，而残炭率不下降；由于呋喃树脂使煤沥青分子隔开从而改善了煤沥青的流动性能；另外加入适量的呋喃树脂可降低煤沥青的黏流活化能，有利于煤沥青在较宽温度范围内进行工艺操作。     

Effect of coal tar pitch modified by sulfur as a binder on the mechanical and tribological properties of bronze-impregnated carbon-matrix composites

Bronze-impregnated carbon-matrix composites were prepared through compression molding, carbonization and impregnation. The mechanism of sulfuration was studied, and the effect of coal tar pitch modified by sulfur as a binder on the mechanical and tribological properties of composites was investigated by varying the content of sulfur. The results showed that the sulfur addition increased the softening point, carbon yield and C/H atomic ratio of coal tar pitch but decreased the toluene solubility and quinoline solubility due to the dehydrogenating polymerization of pitch molecules. The micro-hardness, bending strength and compressive strength of the composites were enhanced by increasing the mass percentage of sulfur and reached a maximum of 160 HV, 132.82 MPa and 293 MPa at 7 wt. % of sulfur, respectively. However, both the hardness and strength of the composites decreased as the content of sulfur increased beyond 7 wt. %. The friction coefficient value of composites increased monotonously, but the wear rate decreased with increasing sulfur content; subsequently, the wear rate reached a minimum of 3.045 × 10⁻⁷ mm³/Nm at 7 wt. % of sulfur and then ascended. The wear mechanisms of the composites were adhesive wear, abrasive wear and oxidative wear. However, adhesive wear and oxidative wear occurred slightly for the composites with the binder modified by sulfur.     

Binderless moulding of green cokes delivered from solvent refined coal and ethylene tar pitch

Green cokes, derived from the co-carbonization of Solvent Refined Coals with ethylene tar pitch, have been moulded into discs without using a binder. Cokes with a range of size of optical texture have been prepared by control of the ratios of the two components of the carbonization blend. The appearance of the discs was assessed by optical and scanning microscopy after calcination to 1200° C. The most acceptable disc was prepared by moulding carbon of a heat treatment temperature (HTT) of 440° C. With cokes of HTT< 440° C excessive dilation adversely decreased the density of the disc. With cokes of HTT > 440° C, dimished cohesion of the coke grains prevented the development of a strong disc on calcination. It is considered that the presence of benzene-soluble (BS) and benzene-insoluble/quinoline-soluble (BI/QS) fractions in the pitch systems contribute to cohesion of coke particles having a HTT of 440° C.     

炭/炭复合材料用煤沥青的改性及性能研究

以对甲基苯甲醛(4-methyl benzaldehyde,简称4-MB)为改性剂,在对甲苯磺酸(PTS)的作用下对煤沥青进行了改性研究.采用傅立叶红外光谱和核磁共振氢谱对煤沥青改性机理进行分析;采用扫描电镜观察改性煤沥青的形貌;采用热解重量分析仪分析改性沥青的热行为.实验结果表明,对甲基苯甲醛在酸性催化剂的催化作用下与煤沥青发生亲电取代反应,改性后煤沥青出现纤维结构,改性沥青的耐热性优良,残炭率大大提高.因此,改性后的煤沥青有望作为优质的炭材料基体前驱体.     

In situ fabrication of carbon nanotube/mesocarbon microbead composites from coal tar pitch

Carbon nanotube/mesocarbon microbead composites have been synthesized from coal tar pitch with carbon nanotubes. How the carbon nanotubes affect the growth and the structure of mesocarbon microbeads are studied. The result shows that the size of beads decreases when more carbon nanotubes are added, and when the ratio of carbon nanotubes is set at 5%, we get the smallest sample with quite uniform shape. Carbon nanotubes exist both on the surface and inside of the samples and they will inhibit the growth and coalescence of these spheres. The addition of carbon nanotubes decreases the graphitization degree of the samples and makes their microtexture tend to be disordered.     

从煤焦油软沥青和苯基硅烷制备硅取代聚芳烃中间相的研究

过滤后的煤焦油沥青分别与一,二,三,四苯基硅烷在1MPa氩气气氛和420℃～460℃温度下共炭化,合成了硅取代聚芳烃中间相。在四种合成中间相中,元素硅的起始加入量均为2%。测定了裂解残留物和硅的收率、可溶性、玻璃转化温度以及裂解残留物的炭收率;并分别以偏光显微镜和电子探针微分析法考察了残留物的微结构和相应的硅分布,硅的收率取决于不同的苯取代硅烷的挥发性和反应性。裂解残留物显示出三种不同的共存相:(a)含有粗镶嵌织构和痕量硅的光学各向异性相;(b)硅含量较高的光学各向同性相;(c)含细镶嵌织构和中等硅含量的光学各向异性相。最后这种中间相主要来自二,三苯取代硅烷与煤沥青的共炭化,是由于硅取代聚芳烃中碳原子并破坏了其分子的平面结构而引起的。     

从煤焦油软沥青和苯基本原则硅烷制备取代聚芳烃中间相的研究

过滤后的煤焦油沥青分别与一、二、三、四苯基硅烷在1MPa氩气气氛和420℃～460℃温度下共碳化，合成了硅取代聚芳烃中间相，在四种合成中间相中，元素硅的起始加入量均为2%，测定了裂解残留物和硅的收率，可溶性，玻璃转代温度以及裂解残留物的炭收率；并分别以偏光显微镜和电子探针微分析法考察了残留物的微结构和相应的硅分布，硅的收率取决于不同的苯取代硅烷的挥发性和反应性。裂解残留物显示出三种不同的共存相：（a）含有粗镶嵌织构和痕量硅的光学各向异性相；(b）硅含量较高的光学各向同性相；(c）含细镶岩织构和中等硅含量的光学各向异性相。最后这种中间相主要来自二，三苯取代硅烷与煤沥青的共炭化，是由于硅取代聚芳烃中碳原子并破坏了其分子的平面结构而引起的。     

Si掺杂煤沥青制备及其炭化产物抗氧化性能的表征

通过煤沥青甲苯可溶性组分与聚碳硅烷共混合低温裂解引入具有抗氧化性的Si杂原子,制备Si掺杂煤沥青在氩气氛中经过900℃处理得到炭化产物。采用FT-IR、XRD、SEM和TG-DSC手段对Si掺杂沥青炭化产物氧化前后抗氧化性能进行表征。研究表明:经过900℃处理得到的炭化产物β-SiC以微晶形式存在,其在900℃氧化后生成的SiO2不能有效地愈合氧化后产物表面的裂纹。该炭化产物在低于950℃氧化时,该炭化产物抗氧化性相对较弱,在950-1500℃温度范围氧化时,其抗氧化性相对较强。     

Fabricated carbon from minimally processed coke and coal tar pitch as a carbon-sequestering construction material

We report the mechanical fracture strength and physical properties of fabricated carbons made from pulverized metallurgical coke bonded with coal tar pitch, followed by pyrolysis. Tensile strength from diametral compression of discs ranged from 9.7 ± 1.3 MPa for materials bonded with 13 wt% pitch to 63 ± 7.1 MPa for materials bonded with 40 wt% pitch. Materials made by dry mixing pulverized pitch with coke were comparable with materials made by mixing coke powder with a solution of pitch in toluene. Strength increased with pyrolysis temperature. Pyrolyzed pitch-bonded coke was significantly stronger and lighter than ordinary Portland cement concrete.     

从煤焦油硬沥青和苯基硅烷制备硅取代聚芳烃中间相的研究

采取软、硬二种沥青与一,二,四苯基硅烷混合物共炭化方式,考察了硅取代聚芳烃中间相的生成。该炭化过程在反应釜中进行,控制实验条件如下:氩气压强1MPa,温度440℃,热裂解时间5h～10h。研究表明:含2%元素硅的初始混合物,不生成硅取代中间相;添加1.0%和0.5%元素硅的硬沥青炭化时明显生成硅取代中间相,但不是单一相。热裂解残留物是硅取代中间相体和均匀分散其中的无硅中间相小球体构成的复合相。     

Analysis of coal tar pitch and smoke extract components and their cytotoxicity on human bronchial epithelial cells

Coal tar pitch and its smoke are considered hazardous by-products and common pollutant generated from coal industry processing. In this study, coal tar pitch and its smoke extracts were characterized by gas chromatography/mass spectrometry (GC/MS) with dimethylsulfoxide. We identified only 0.3025% of components in the total coal tar pitch using GC/MS. Among 18 identified compounds, polycyclic aromatic hydrocarbons (PAHs) has the highest relative abundance (0.19%). The remaining components were composed of monocyclic aromatic hydrocarbons, heterocyclic compounds and alkenes. In contrast, among 38 coal tar pitch smoke extract constituents that have been profiled, 87.91% were PAHs, and the remaining 12.09% were composed of monocyclic aromatic hydrocarbons, heterocyclic compounds and alkenes. The cytotoxic effect of coal tar pitch and its smoke extracts on BEAS-2B cells were also evaluated by MTT assay. BEAS-2B cells exposed to coal tar pitch showed a non dose-dependent U-shaped cytotoxicity with a dosage for maximal inhibitory of 3.75 mg/L. In contrast, BEAS-2B cells exposed to coal tar pitch smoke extracts showed a dose dependent cytotoxicity with a LC(50) of 8.64 mg/L. Our study demonstrated the significant different composition and cytotoxicity of coal tar pitch and its extracts, suggesting two different underlying mechanisms that are pending future investigation.     

Blending mesophase pitch to improve its properties as a precursor for carbon fibre Part 1 Blending of PVC pitch into coal tar and petroleum-derived mesophase pitches

The blending of mesophase pitch with isotropic PVC pitch was studied to improve their properties as a precursor for carbon fibre. PVC pitch prepared at 420° C which remained almost isotropic was found to be miscible with coal tar-derived mesophase pitch without reducing the anisotropic content and spinnability. The tensile strength of pitch fibres remained unchanged by the blending; however, the reactivity for stabilization was enhanced. The resultant carbon fibres from the blend exhibited slightly higher tensile strength. In contrast, petroleum-derived mesophase pitch failed to dissolve the PVC pitch, leaving a number of isotropic droplets. The structural factors of mesophase pitches with regard to their compatibility with PVC pitches are briefly discussed.