共查询到18条相似文献,搜索用时 802 毫秒
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碳纳米管的独特结构赋予了其优良性质,被认为是聚氨酯复合材料的理想添加相.然而,碳纳米管的分散效果直接影响了聚氨酯/碳纳米管复合材料的性能.主要介绍了碳纳米管在聚氨酯复合材料制备过程中的分散方法(分别采用机械分散、超声分散和磁力分散3种物理分散方法),分析了分散时间、分散频率等参数对分散效果的影响.结果表明,3种分散方法中,分散效果由好到差依次为超声分散、磁力分散和机械分散;并且随着分散时间的延长和分散频率的增大,分散效果总体上趋于变好;而对于磁力分散和超声分散,超过一定时间后又会出现碳纳米管重新团聚,最佳分散时间分别为2.0h和1.5h. 相似文献
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采用表面活性剂和超声辅助的混酸处理工艺对碳纳米管进行了表面修饰,均获得了分散均匀的碳纳米管悬浮水溶液,利用傅立叶红外吸收光谱及Zeta电位等手段对其分散机理进行了分析;采用快速溶胶一凝胶法,制备了多种碳纳米管含量的石英基复合粉体,透射电镜观察显示两种修饰碳纳米管表面的方法都有效提高了碳纳米管在石英基体的分散性,制备出了均匀的碳纳米管/石英复合粉体。 相似文献
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纳米氧化锡锑(ATO)粉体的高效分散和长期稳定是制备纳米透明隔热材料的关键因素。首先考查了分散剂、pH值、粉体表面特性、分散工艺、粘度等参数对分散稳定性的影响,采用沉降法、分光光度计法、电镜法对分散效果进行表征。结果表明,采用复合分散剂,其添加量占粉体质量5%,同时采用超声和球磨相结合的分散方式可以使分散效果达到最佳;通过增加粉体表面球度和分散介质粘度的方法可以有效提高粉体的分散稳定性,pH值对粉体分散稳定性影响不大。最后,通过优化分散工艺得到了高度均匀、长期稳定的纳米ATO分散液及纳米透明隔热涂料。 相似文献
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碳纳米管与铝基体的结合,可以获得导电和导热性良好及综合力学性能优异的复合材料,有望成为新一代轻质高强、结构功能一体化的复合材料.在制备碳纳米管增强铝基复合材料过程中,碳纳米管的团聚将降低界面结合,诱发缺陷产生,导致性能大幅下降,因此,调控优化碳纳米管的分散状态、含量成为获取良好界面结合,获得高性能碳纳米管增强铝基复合材料的关键.基于此,综述了国内外均匀分散碳纳米管的方法,通过物理作用、化学作用和物理化学共同作用的方式进行分类,并详细介绍了高能球磨、摩擦搅拌、化学气相沉积、湿法球磨等主要的碳纳米管在铝基体中的分散方法.分析了不同分散方法的特点及其分散效果,最后总结了分散过程中存在的分散效果、缺陷的平衡、大长径比、高含量碳纳米管分散及分散评价方法等关键问题,并展望了未来在铝及其合金基体中碳纳米管分散方法的发展方向. 相似文献
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剪切场作用下团聚体分散的计算机模拟 总被引:1,自引:0,他引:1
利用计算机模拟研究了三种简单立方网格上的三维分形团聚体的团聚过程,并对团聚体在简单剪切流场中分散规律进行了研究。结果表明,团聚体在简单剪切场作用下的分散与其团聚机理和分形维数有关。分形维数较小的DLA团聚体分散所需的临界应力随团聚体增大而减小;分形维数最大的Eden团聚体的临界应力随其增大而增大;LTA团聚体的临界应力随其增大而变化不大。研究还表明,随着破裂面位置向团聚体内部推进,三种团聚体分散所需的流场临界应力都显示了增大的趋势。 相似文献
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In this paper, high pressure homogenization (HPH) served as the main dispersion method for making carbon nanotubes (CNTs)-modified composite materials. A new quantitative approach was proposed to evaluate the dispersion of CNTs in epoxy resin by combining microscopic images with maximum likelihood estimation theory. The results were in good agreement with those obtained from optical observation and ultraviolet–visible (UV–vis) absorbance measurement. Moreover, the dispersion process specific to HPH processing was analyzed with the aid of the proposed approach. The changes of the morphologies and lengths of CNTs in HPH were illustrated. It was found that, in the first few cycles, the lengths of CNTs fell significantly and the entanglements remained severe. In the following cycles, individual CNTs were gradually separated from agglomerates and the lengths experienced a slow decline. After homogeneous dispersion, the transverse tensile properties of CNTs-modified carbon fiber reinforced epoxy composites (CFRP) got obviously ameliorated. 相似文献
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为了提高分散作用效果,选用聚乙二醇-20000(PEG-20000)、十二烷基硫酸钠(SDS)及二者组成的复配分散剂,利用机械球磨与添加分散剂相结合的分散方法制备了钡铁氧体浆料,通过考察分散剂的用量、浆料的pH值、zeta电位对分散性的影响,根据红外光谱分析,研究了分散剂的分散效果及作用机理,并测定了分散前后磁场成型各向异性钡铁氧体材料的磁性能。结果表明:加入分散剂可以改善钡铁氧体的分散效果,且SDS和PEG-20000的用量为钡铁氧体质量的1%和2%时,分散效果最好。SDS和PEG-20000均为静电和空间位阻稳定作用。分散后磁场成型各向异性钡铁氧体材料的磁性能得到提高。 相似文献
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超细煤粉的静电分散研究 总被引:1,自引:1,他引:1
为了解决超细煤粉加工和利用过程中的聚团问题,提高煤粉的附加值和功能化利用,本文中采用正交试验的方法研究了静电分散对超细煤粉的分散效果及其主要影响因素,并用高精度粒度分析仪对静电分散前后粒度进行了检测。实验结果表明,静电分散后的粒度明显变小,静电分散作用可保持7d左右。静电分散方法能有效分散空气中超细煤粉的聚团。 相似文献
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The influences of admixtures on the dispersion, workability, and strength of carbon nanotube-OPC paste mixtures 总被引:1,自引:0,他引:1
Carbon nanotubes (CNT) have excellent mechanical properties and have the potential, if combined with Ordinary Portland Cement (OPC), traditionally a brittle material in tension, to become a nano-composite with superlative mechanical properties. However, highly attractive van der Waals forces between CNTs create coherent agglomerates that prove difficult to disperse within the cement matrix and reduce the fluidity of the fresh mixture. Good dispersion of CNTs, while maintaining good workability of fresh OPC-CNT paste mixtures, is a prequalification before CNT-cement nanocomposites can be considered as a future building and construction material with enhanced mechanical properties. This paper reports the results of investigations of the dispersion, workability, and strength of CNT aqueous and CNT-OPC paste mixtures, with and without several generically different dispersants/surfactants that are compatible as admixtures in the manufacture of concrete. These include an air entrainer, styrene butadiene rubber, polycarboxylates, calcium naphthalene sulfonate, and lignosulfonate formulations. Aqueous mixtures were initially assessed for dispersion of CNTs, followed by workability testing of selected OPC-CNT-dispersant/surfactant paste mixtures. A broad range of workability responses were measured and the CNT dispersion within hardened pastes was qualitatively assessed by SEM analysis. 相似文献
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Haipeng Li Lihui Wang Chunyong Liang Zhifeng Wang Weimin Zhao 《Materials Science and Engineering: B》2010,166(1):19-23
In the present work, we use chemical vapor deposition of methane to disperse carbon nanotubes (CNTs) within hydroxyapatite (HA) powder. The effect of different catalytic metal particles (Fe, Ni or Co) on the morphological and structural development of the powder and dispersion of CNTs in HA powder was investigated. The results show that the technique is effective in dispersing the nanotubes within HA powder, which simultaneously protects the nanotubes from damage. The results can have important and promising speculations for the processing of CNT-reinforced HA-matrix composites in general. 相似文献