Intercalation structure and toughening mechanism of graphene/urea‐formaldehyde nanocomposites prepared via in situ polymerization

Based on the industrialized graphene (GN) product, a series of graphene/urea‐formaldehyde nanocomposites were synthesized via in situ polymerization by incorporation of silicon coupling agent with terminal amino groups (SA) as the compatibilizer. The results showed that addition of SA coupling agent led to much more efficient grafting of UF molecules on the GN surface with high layer thickness by formation of hydrogen bonding, and thus complete exfoliation and uniform dispersion of GN were achieved for the composites. Compared with neat UF, the addition of 1.0 wt% GN resulted in a roughly 25% increase in tensile strength and 12% increase in impact strength; meanwhile the impact fracture surfaces of the composite showed obvious ductile fracture characteristics, indicating the reinforcing and toughening effect of GN on the UF matrix. With increasing GN content, the storage modulus, glass transition temperature and crosslinking density of UF increased, while the tan δ_max decreased, suggesting that a double crosslinking network structure with GN centered crosslinking point and chemical crosslinking point of UF molecular chains formed, leading to improvement in the stiffness of the composites. The present work showed promising potential for developing high performance UF resin on an industrial scale. © 2017 Society of Chemical Industry     

On manifestation & physics of the Kurdjumov and spillover effects in carbon nanostructures,under intercalation of high density hydrogen

Abstract

Some experimental evidences and the physics (thermodynamics) of the nanoscale self-intercalation of high-density gaseous molecular hydrogen (ρ?≈?0.045?g/cm³, T?≈?300?K) into surface nanoclusters in highly oriented pyrolytic graphite and epitaxial graphene, as well as the nanoscale self-intercalation of high density solid molecular hydrogen (ρ?≈?0.5?g/cm³, T?≈?300?K, the compressed pressure ～ 0.5 Mbar) into graphite nanofibers are considered, with regard to the problem of compact and efficient hydrogen on-board storage and other clean energy applications. Perspectives of further developments of these results are considered, as well.     

聚合物/粘土纳米复合材料制备研究现状

对聚合物／粘土纳米复合材料的研究进展进行了概述。根据插层机理和方法的差别，将插层法分为三类：(1)单体插层原位聚合；(2)溶液插层复合；(3)熔融插层复合。简要分析了插层的热力学与动力学原理，介绍了聚合物／粘土纳米复合材料的优异性能及其在实践中的应用，展望了聚合物／粘土纳米复合材料的开发及应用前景。     

混酸系无硫膨胀石墨的制备

以硝酸、磷酸为浸泡剂，在强氧化剂的作用下，对无硫膨胀石墨的制备进行了初步研究。最佳工艺条件为：反应时间1h，膨化温度1000℃，膨化时间30s；石墨：硝酸：磷酸：高锰酸钾为1：1：0．8：0．1。     

某工程岩石地基中溶蚀软弱夹层形成原因分析及地基强度探讨

该文分析了岩石地基中溶蚀软弱夹层的形成原因、对比了其室内试验、旁压试验及静力载荷试验结果 ,论述了溶蚀软弱夹层地基强度采用室内试验及旁压试验确定 ,其数值将大于实际承载力 ,偏于不安全 ,宜采用静力载荷试验确定。     

复合插层剂制备可膨胀石墨研究

无机化合物与有机化合物联合作复合插层剂使用,与天然鳞片石墨、浓硝酸(浓HNO3)、高锰酸钾(KMnO4)等原料经氧化酸化插层、水洗、干燥过程制备无硫可膨胀石墨,利用正交试验方法确定了最佳工艺条件:天然石墨、KMnO4、浓HNO3、P2O5、冰HAc的质量比为1∶0.08∶3.4∶0.4∶0.6,产品膨胀容积可达300 ml/g,挥发分和灰分分别比单一插层剂制得的产品低。     

PVA/MMT/TiO2三元复合薄膜制备与研究

通过插层法和溶胶-凝胶法制备了PVA/MMT/TiO2三元复合薄膜。结果表明，MMT、TiO2均匀分散于基体中，由于无机柱子的协同增强作用．PVA／MMT／TiO2三元复合薄膜的热分解温度比纯PVA薄膜提高了59℃：MMT的质量一定时．复合薄膜的拉伸强度、直角撕裂强度和弹性模量随TiO2质量分数的增加而增加。并在TiO2质量分数为1.0％时分别达到最大值，但断裂伸长率则一直下降.MMT质量分数为3．0％、TiO2质量分数为1．0％、pH为7、搅拌3h和反应温度90℃条件下．制得的复合薄膜的性能最佳。     

微波法制备纳米多孔石墨

介绍了微波法制备纳米级多孔石墨的过程 ,以及采用汞压入法测量该多孔石墨的孔结构。与高温电炉膨化法相比 ,微波法制备的多孔石墨具有很好的纳米孔隙 ,孔径分布基本上在 4～ 10 0nm范围内 ;而传统的高温电炉膨化的多孔石墨的孔隙直径分布 ,在纳米和微波之间的过渡区域 ,二者之间存在差别。同时 ,实验结果显示纳米多孔石墨的孔结构 ,受到石墨插层物制备时水洗次数 (水洗液的pH值 )、膨化过程的微波作用时间以及鳞片石墨细度的影响     

从影响承载力角度探讨水冲气举法沉桩施工控制

本文就水冲气举法辅助沉桩施工对单桩承载力的影响因素进行分析,探讨为消除这些影响因素的施工控制方法,为工程实践提供参考。