膨胀石墨的制备及应用研究进展

对国内外膨胀石墨的制备方法进行了系统的分析和对比,总结了各种制备方法的优缺点,在此基础上,论述了膨胀石墨作为吸附材料、柔性材料、储能材料、电池材料、防火阻燃材料、膨胀石墨发烟材料的应用进展。     

可膨胀石墨的化学氧化法制备研究进展

对可膨胀石墨的化学氧化法制备研究的最新进展进行了综述。重点介绍了低硫可膨胀石墨、无硫可膨胀石墨和低温可膨胀石墨的化学氧化法制备研究进展，并对化学氧化法制备可膨胀石墨的其他方面进展也作了简要的介绍。     

膨胀石墨制备及在环境保护中的应用现状

文章综述了环境友好型材料膨胀石墨目前常用的制备和改性方法,并对膨胀石墨及其复合材料在环境保护的应用现状进行了介绍。     

一种交联状碳纤维包覆膨胀石墨复合材料的制备方法

正本发明涉及膨胀石墨复合材料的制备方法。本发明是要解决现有的膨胀石墨比表面积低的技术问题。制备方法:(1)用鳞片石墨制备膨胀石墨;(2)将十六烷基三甲基溴化铵溶解于盐酸水溶液中,再加入膨胀石墨,然后滴加吡咯单体,搅拌进行聚合反应,得到聚吡咯/膨胀石墨复合材料;(3)将聚吡咯/膨胀石墨复合材料放入气氛管式炉中进行碳化反应,得到交联状碳纤维包覆膨胀     

PEMFC用石墨/酚醛树脂复合板的膨胀石墨表面改性

提出采用膨胀石墨对石墨/酚醛树脂复合板进行表面改性,改性后复合板的体积电阻和接触电阻都有显著降低。考察了膨胀石墨的膨胀体积、膨胀石墨层厚度等因素对膨胀石墨改性复合板的接触电阻和体积电阻的影响。结果表明,膨胀石墨的膨胀体积是影响膨胀石墨改性复合板体积电阻和接触电阻的重要因素。随膨胀石墨层厚度增加,接触电阻先减小而后趋于不变。复合板中酚醛树脂含量越高,采用膨胀石墨表面改性对降低复合板的体积电阻和接触电阻的效果越显著。     

超声处理配合烧结成型工艺制备PEEK/石墨复合材料

引进超声波对聚醚醚酮(PEEK)/膨胀石墨/无水乙醇体系进行震荡,层间剥离膨胀石墨的同时实现了膨胀石墨在复合材料体系中的良好分散,烘干得到成型前驱体。进一步地,采用烧结成型工艺制备了PEEK/膨胀石墨复合材料片材。考察了超声液体介质对膨胀石墨剥离效果的影响,同时研究了膨胀石墨含量以及烧结成型过程工艺参数对复合材料片材导电性能和力学性能的影响。原子力显微镜测试结果显示,超声过程最佳液体介质为无水乙醇,处理之后的膨胀石墨片层从21 nm降至1.13 nm;最终制备的PEEK/膨胀石墨复合材料片材在膨胀石墨质量分数为60%时,电导率达到82.64 S/cm,而弯曲强度为66.78 MPa。     

微波法膨胀石墨的制备及其对油类污染物吸附性能的研究

对黑龙江鸡西某地原矿C固品位为9.45%的石墨矿进行选矿提纯试验,石墨精矿C固含量为96.67%,-0.074 mm累计含量为28.74%,利用该产品采用微波法制备了膨胀石墨,膨胀体积为268 mL/g,回收吸附了油质的膨胀石墨,压榨后使其充分燃烧,燃烧后的膨胀石墨进行扫描电镜分析,试验及分析结果表明该燃烧后的膨胀石墨仍然呈疏松多孔结构,具有较大的比表面积,因此可以继续循环使用。该研究扩展了膨胀石墨可再生利用相关研究,能够降低膨胀石墨处理水污染的成本。     

膨胀石墨/丁腈橡胶复合材料的性能研究

膨胀石墨是一种层状材料,具有优异的导电性和导热性。本文采用机械共混的工艺方法制备了膨胀石墨/丁腈橡胶复合材料,考察了膨胀石墨对丁腈橡胶导电性能和力学性能的影响。实验表明,当加入20份高耐磨炭黑时,丁腈橡胶具有优异的综合力学性能,其最大拉伸强度为12.85 MPa,邵尔A硬度为 60.4 度。采用直接共混的方法制备膨胀石墨/高耐磨炭黑/丁腈橡胶复合材料,并与炭黑/丁腈橡胶复合材料进行比较,研究了材料的力学性能与导电性能。结果表明添加膨胀石墨后可大大的提高炭黑/丁腈橡胶复合材料的导电性能和力学性能。当不含膨胀石墨时,丁腈橡胶复合材料基本不表现出导电性能。     

膨胀石墨填充聚氯乙烯导热复合材料的性能研究

以膨胀石墨(EG)为导热填料,利用先开炼后模压的成型方法,制备膨胀石墨(EG)增强聚氯乙烯(PVC)导热复合材料,考察了含量变化对板材微观结构、导热系数、拉伸性能、弯曲性能的影响,并与其他成型方法进行对比分析。结果表明,膨胀石墨以石墨微片存在于树脂基体中,并随着含量的增加逐渐增强板材的导热性;填充膨胀石墨在增大板材刚度的同时,也会降低板材的拉伸强度和弯曲强度,当膨胀石墨含量为15%时力学强度最优。     

改性膨胀石墨对甲醛的吸附性能研究

对含甲醛的废气处理一般采用吸附法，本文以天然鳞片石墨、浓硫酸、浓硝酸、双氧水、重铬酸钾为原料，采用改进的二次氧化法制备膨胀石墨，并对所制得的膨胀石墨进行表面改性。运用改性后的膨胀石墨对甲醛进行静态和动态吸附实验，实验结果表明，改性后的膨胀石墨对甲醛气体的吸附能力有大幅度提高。研究了改性前后膨胀石墨孔结构的变化及其对饱和吸附量的影响，并对改性机理进行了初步探讨。     

Recovery of heavy oil from contaminated sand by using exfoliated graphite

Heavy oil was recovered from contaminated sand through capillary suction into exfoliated graphite with differentpacked densities by using model sands, alumina powders, with different particle sizes. For efficient recovery it was important to have an appropriate combination of average size of sand particles and packed density of exfoliated graphite. Pumping of heavy oil into exfoliated graphite occurs as a balance in an attracting capillary force between exfoliated graphite and sand, the former being stronger than the latter because of the hydrophobic nature of the surface of graphite.     

Heavy oil sorption and recovery by using carbon fiber felts

On fibrous carbon materials, including activated carbon fibers, sorption capacity for heavy oils, less viscous A-grade and more viscous C-grade, was determined. Sorption capacity depended strongly on their bulk density; the correlation was the same as that found previously on exfoliated graphite and carbonized fir fibers. On carbon fiber felts, excellent recycling performance was observed, though sorption capacity was not so high as on exfoliated graphite and carbonized fir fibers. By filtration under suction, about 90% of sorbed A-grade heavy oil could be recovered and no decrease in sorption capacity was detected even after eight cycles. By washing with solvents, n-hexane for A- and C-grade oils and A-grade oil for C-grade oil, almost 100% recovery with no marked reduction in sorption capacity was found for each cycle. For the felts of PAN-based carbon fibers, rather severe operations for oil recovery, centrifugation and squeezing with twisting, could be applied without pronounced decreases in sorption capacity and recovery ratio.     

饮用水源突发性柴油污染的吸附法应急处理模拟试验

通过室内模拟实验,研究了膨胀石墨对饮用水源水突发性柴油污染的应急消减性能。考察了振荡速率、水体pH、膨胀石墨投加量和水温对吸附效果的影响,测定了吸附等温线,对吸附规律进行了探讨。结果表明,膨胀石墨可快速高效地消减突发性柴油污染。在本研究条件下,振荡速率、水体pH和水温对柴油的吸附无显著性影响。当膨胀石墨投加量为5g/L时,历时5s即可将1 000 mg/L的柴油去除97%以上。等温吸附规律可用Freundlich模型较好的拟合,拟合得到的线性方程可为应急处理水源地突发柴油污染提供基础模型。     

Preparation and characterization of graphite nanosheets from ultrasonic powdering technique

Natural flake graphite was exfoliated into exfoliated graphite via an acid intercalation procedure. The resulting exfoliated graphite was a worm-like particle composed of graphite sheets with thickness in the nanometer scale. Subjecting it to ultrasonic irradiation, the exfoliated graphite was effectively further foliated into isolated graphite nanosheets. SEM, TEM, SAD, laser counting, and BET measurements revealed that the graphite nanosheets prepared with 10 h irradiation were about 52 nm in thickness and 13 μm in diameter. FTIR examination showed that there were oxygen-containing groups presented on the surface of the exfoliated graphite. This result substantiated the statement reported in the literature that acid treatment could result in oxidization of carbon bonds on graphite surface.     

A rapid and efficient method to prepare exfoliated graphite by microwave irradiation

Exfoliated graphite materials had been rapidly and efficiently prepared by microwave irradiation in a short time (about 4 min including 3 min mixing and 1 min microwave irradiation). The promotion of the intercalation by microwave irradiation was proven by X-ray diffraction. With increasing content of oxidant and intercalation agent, the expanded volume of exfoliated graphite increased at first and then decreased. When the weight ratio of natural graphite and nitric acid to potassium permanganate was set at 1:2:1, the expanded volume of exfoliated graphite reached the maximum value (312 mL/g) and sorption capacity of this exfoliated graphite was 56 g of engine oil and 32 g of kerosene per 1 g of exfoliated graphite.     

膨胀石墨的化学制备法和影响其质量的因素

膨胀石墨作为新型炭素密封件材料广泛用于石油、化工、电力、冶金、医药、食品、机械等行业。介绍了用化学法制备的膨胀石墨的过程中石墨的粒度、酸化液配比、pH、膨胀温度对膨胀石墨质量的影响。     

Sorption and recovery of heavy oils using carbonized fir fibers and recycling

Fibers extracted from fir trees (Abis sachalinensis Fr. Schm) and carbonized at either 380 or 900°C were found to have a high performance for sorption, recovery and recycling of heavy oils, even the viscous ones. Sorption capacity showed strong dependence on bulk density of carbonized fibers, suggesting the importance of the space formed among entangled fibers: 60-80 g/g for bulk density of ca. 6 kg/m³ and 10-20 g/g for density of ca. 40 kg/m³. The sorption capacity of carbonized fir fibers for a less viscous heavy oil was almost comparable to that of exfoliated graphite which was also reported to have high capacity. For viscous oil, however, carbonized fir fibers had higher sorption capacities than exfoliated graphite, particularly when the bulk densities are high. Less viscous heavy oil could be recovered by simple filtration under suction and the fibers could be reused for the sorption of oil, although the sorption capacity decreased with recycling. Their recycling performance was also strongly dependent on their bulk density: the sorption capacity of 6 kg/m³ fibers after the eighth cycle became less than 60% from that of the first cycle, but for 35 kg/m³ fibers it was more than 90%. Viscous oil could be recovered only by washing with n-hexane and also with less viscous oil. After washing the fir fibers could be reused for the sorption of oil.     

Sorption and recovery of heavy oils using exfoliated graphite Part IV: Discussion of high oil sorption of exfoliated graphite

The correlation between sorption capacity for heavy oil with a viscosity of 0.004 kg/m s and pore volume measured by a mercury porosimeter was studied on exfoliated graphite samples with different bulk densities. Pore volume measured by using the conventional dilatometer (N-type cell), which gives information on the pore size from 0.004 to 4 μm, was too low to explain the sorption capacity measured. However, pore volume measured by a special dilatometer (U-type cell) for large pore sizes up to 600 μm was very closed to sorption capacity. Pore volume measured by this U-type cell showed a linear relation to sorption capacity of exfoliated graphite samples, of which the slope was the same value as the density of heavy oil used (860 kg/m³). Therefore, large pores, which are reasonably assumed to be inter-particle pores among entangled worm-like particles of exfoliated graphite, were responsible for the large sorption capacity of heavy oils. Intra-particle pores inside and cleavage-like pores on the surface of worm-like particles were assumed to assist the capillary pumping of heavy oil.     

Regenerated cellulose nanocomposites reinforced with exfoliated graphite nanosheets using BMIMCL ionic liquid

Green nanocomposites of regenerated cellulose/exfoliated graphite nanosheets films with low nanofiller loadings were prepared using environmentally benign 1-butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid. X-ray diffraction revealed well developed intercalated nanocomposites. The tensile strength and Young's modulus of the prepared nanocomposites were increased by 97.5% and 172% respectively when 0.75 wt.% and 1 wt.% exfoliated graphite nanosheets were added. The results were validated using the Halpin–Tsai model. The exfoliated graphite nanosheets were unidirectionally aligned in the regenerated cellulose parallel to the surface of the nanocomposites as revealed by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Also, the TEM and FESEM revealed uniform dispersion of the exfoliated graphite nanosheets and good interaction between the nanofillers and the matrix. The addition of the exfoliated graphite nanosheets enhanced the thermal stability and reduced the water absorption and diffusivity of the nanocomposites.