氨基功能化石墨烯/水性聚氨酯复合材料的制备与性能研究

文章以2,4-甲苯二异氰酸酯(2,4-TDI)为架桥剂,制备了表面含伯胺基的功能化石墨烯(N-FGNs)。然后将其与末端含异氰酸酯的聚氨酯树脂混合,通过伯氨基与异氰酸酯之间的反应制备了两者之间存在共价键的石墨烯/水性聚氨酯(N-FGNs/WPU)复合材料。透射电镜(TEM)和扫描电镜(SEM)表征结果表明,N-FGNs可均匀分散在聚氨酯中,同时两者之间存在很强的界面作用力。当N-FGNs的添加量为1.0%时,该N-FGNs/WPU复合材料的拉伸强度相对于纯的WPU材料提升了77%,40℃时的储能模量E′提高了930%,断裂伸长率仅下降了4%。     

石墨烯/聚酰亚胺复合膜的制备及性能

分别以氧化石墨烯(GO)和改性氧化石墨烯(iGO)为添加物,通过溶液混合的方法制备了氧化石墨烯/聚酰亚胺(GO/PI)和改性氧化石墨烯/聚酰亚胺(iGO/PI)复合膜,采用傅里叶变换红外光谱仪、扫描电子显微镜、电子万能试验机、热机械分析仪对复合膜的结构与性能进行分析.结果表明:iGO/PI复合膜的相容性及拉伸力学性能均高于GO/PI复合膜;GO的加入使GO/PI复合膜的玻璃化温度较纯PI膜升高,而iGO使iGO/PI复合膜的玻璃化温度较纯PI膜降低.     

石墨烯/PAN纳米复合膜的制备及其力学性能

以改进的Hummer法制备了氧化石墨烯(GO),并以抗坏血酸(L-AA)为还原剂制备了还原性氧化石墨烯(rGO).以石墨烯为添加物,采用静电纺丝的方法制备了石墨烯/聚丙烯腈(GO/PAN)纳米纤维复合膜.使用场发射扫描电镜、X射线衍射、红外光谱以及热重分析对石墨烯进行了研究,测试了石墨烯对纳米复合纤维材料力学性能的影响.结果表明:当添加的GO质量分数为0.3%时,纺制的纤维平均直径为103nm,复合膜的力学性能有所提高,比纯PAN膜的拉伸强度提高了42.4%,断裂伸长率增加了32.5%;当GO质量分数超过0.3%时,复合膜的力学性能变差;当GO和rGO质量分数均为0.3%时,GO/PAN复合膜的力学性能优于rGO/PAN复合膜.     

相转移法制备高性能石墨烯/环氧树脂复合材料

通过水合肼还原1-乙烯基-3-乙基咪唑四氟硼酸盐(IL)修饰的氧化石墨烯(GO)得到IL修饰的还原氧化石墨烯(IL-rGO),以1-(环氧乙烷-2-基甲基)-1H-吲哚为相转移剂,利用阳离子-π辅助的相转移法将IL-rGO引入到环氧树脂中,采用三乙烯四胺为固化剂,制备了石墨烯/环氧树脂复合材料。利用紫外-可见吸收光谱、拉曼光谱、X射线衍射、扫描电子显微镜和拉伸试验等对复合材料的结构、形貌和机械性能进行了表征。结果表明：当IL-rGO的掺杂质量分数为0.3%时,复合材料具有最优的力学性能,拉伸强度为96.0 MPa,断裂伸长率为11.1%,与纯环氧树脂相比,分别提高了77%和141%。     

改性石墨烯/聚氨酯复合乳液的合成及性能表征

通过逐步聚合反应将改性氧化石墨烯(DIGN)接枝到水性聚氨酯(WPU)链段中,制备得到DIGN/WPU纳米复合乳液。通过IR、AFM、SEM对氧化石墨烯(GO)、DIGN、WPU及DIGN/WPU纳米复合材料的结构进行表征;并研究了DIGN用量对乳液粒径,流变性能及其胶膜的热稳定性和力学性能的影响。结果表明:DIGN的引入使得乳液具有了假塑性流体特性,并随DIGN含量的增加,乳液黏度,粒径及分布指数增大,纳米复合材料的热稳定性明显改善;当w(DIGN)=1wt%时,拉伸强度增加80.33%,杨氏模量提高192.11%,断裂伸长率下降了42.74%。     

氧化石墨烯增强环氧树脂复合材料的制备及其力学性能研究

以天然石墨为原料，利用改进的Hummers法制备氧化石墨烯，并对其进行X-射线衍射（XRD）和傅里叶变换红外光谱（FT-IR）表征。之后利用一种新型的有机溶剂三缩水甘油基对氨基苯酚（TGPAP）作为相转移剂和表面活性剂，将氧化石墨烯（GO）从水溶液转移到环氧树脂基体中，去除水分，加入固化剂进而得到混合液，最后利用浇铸法得到复合材料。通过万能测试拉力机对复合材料的拉伸性能和弯曲性能进行测试，结果表明氧化石墨烯的加入能够有效增强复合材料的力学性能：在添加0.1%（质量分数）的氧化石墨烯时，复合材料拉伸强度达到最大值77.29 MPa，与不添加氧化石墨烯相比提高了26.60%；在添加1.0%的氧化石墨烯时，拉伸模量达到最大值2 451.99 MPa，与纯环氧树脂相比提高了21.69%。     

高强高韧超支化聚酰胺胺/氧化石墨烯仿贝壳复合膜

文章采用超支化聚合物聚酰胺胺(HPAMAM)和氧化石墨烯(graghene oxide,GO),通过真空抽滤自组装的方法制备了仿贝壳复合材料,并对其用京尼平进行了适当的交联。采用透射电子显微镜(transmission electron microscope,TEM)对GO进行了表征,采用红外光谱(infrared spectroscopy,IR)、扫描电子显微镜(scanning electron microscope,SEM)、X-射线衍射仪(X-ray diffraction,XRD)和电子万能试验机对HPAMAM/GO复合膜的结构和力学性能进行了表征。结果表明:HPAMAM/GO复合膜呈现出类似于贝壳的"砖"和"泥浆"排列的层状结构;随HPAMAM在复合膜中质量分数的提高,复合膜的延展性不断提高;在交联后,G-HPAMAM/GO复合膜的力学性能显著提高,拉伸强度约为150 MPa;复合膜保持了很高的韧性,其断裂伸长率高达10%以上。因此HPAMAM在构筑高强高韧仿贝壳复合材料方面具有非常高的研究价值。     

TPU/PVB复合材料的制备及性能

 通过熔融共混方法,制备了热塑性聚氨酯弹性体/聚乙烯醇缩丁醛(TPU/PVB)复合材料。采用红外光谱、转矩流变仪、差示扫描量热、热失重、拉伸测试等分析方法对复合材料的结构、加工流变性能、热学性能和力学性能进行研究。分析结果表明,TPU 可明显改善PVB 的加工性能。当PVB:TPU=75:25 时,复合材料的平衡扭矩为7.2 N·m,相对于纯PVB 而言,平衡扭矩的降幅达42.4%;增塑剂邻苯二甲酸二丁酯(DBP)可改善TPU/PVB 复合材料的加工性能。当PVB:TPU=75:25,DBP 加入量为20%时,复合材料的平衡扭矩由7.2 N·m 降至4.5 N·m。而此时复合材料的拉伸强度与初始相比降低了13 MPa,断裂伸长率从24%增加到162%;相对于纯PVB,复合材料的熔融温度降低了10℃,分解温度升高了18℃。     

改性氧化石墨烯/TiO_2的制备及在氨氮废水处理中的应用

将氧化石墨烯(GO)改性,得到了氨基化改性的氧化石墨烯.再将氨基化改性的氧化石墨烯(GO)与TiO_2复合,制备了氨基改性的氧化石墨烯(GO)与TiO_2复合材料.用所制备的复合材料在可见光照射下,去除溶液中的氨氮,分别考察了不同因素对氨氮去除效率的影响.     

文冠果壳纤维/高密度聚乙烯复合材料的力学性能

 为了充分拓展文冠果壳在复合材料领域的应用,优化其复合材料的制备工艺,探索力学性能随纤维质量分数的变化规律,采用未处理的纤维作为对比,将文冠果壳纤维表面进行碱、硅烷偶联剂及碱-硅烷偶联剂处理。采用双螺杆挤出机熔融共混与注塑成型的方法,制备文冠果壳纤维/高密度聚乙烯复合材料。考察了制备工艺、纤维质量分数对复合材料拉伸强度、断裂伸长率、弹性模量和冲击强度的影响。研究表明,经过二次双螺杆熔融共混,复合材料的拉伸强度和断裂伸长率提高。随着纤维质量分数的增加,复合材料的拉伸强度和断裂伸长率降低,弹性模量增加,冲击强度呈波浪状变化。复合材料断面上纤维断裂机制和剥落机制并存。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that