干燥预处理对EVA可再分散乳胶粉性能的影响

通过试验用NaOH稀溶液、硅溶胶和聚乙烯醇(PVA)对乙烯-醋酸乙烯酯(EVA)乳液进行干燥预处理,采用喷雾干燥法制备EVA可再分散乳胶粉,并讨论pH值、硅溶胶、PVA对EVA可再分散乳胶粉含水率、残渣率、再分散性及再分散液胶膜等性能的影响.试验结果表明,将EVA乳液pH值调节至9,用乳液质量25%的硅溶胶和5%的PVA对乳液进行干燥预处理,在雾化机旋转盘转速为21000r/min,进出口温度分别为170℃和90℃,进料速度为80g/min条件下进行喷雾干燥,制得的EVA可再分散乳胶粉含水率(ω=2.35%)和残渣率(ω=3.70%)低、再分散性及再分散液成膜良好.     

可再分散型乳胶粉制备方法

本文提出改造可再分散型乳胶粉喷雾制备及干燥系统。在可再分散型乳胶粉中添加低聚合度聚乙烯醇保护胶体,运用内增塑改性,使得成品喷雾液粘度控制在150cps以下,固含量在35%~40%。本技术是对现有VEOVA/VAC型可再分散型乳胶粉技术的改进,获得的产品再分散性大于90%,且获得的胶粉粒径较细,堆积密度高于常规方法。     

可再分散性乳胶粉对砂浆力学性能的影响

研究了不同掺量下可再分散性乳胶粉对砂浆抗压强度、抗折强度的影响。试验结果表明:随着乳胶粉掺量的增加,砂浆的抗折强度较普通砂浆有大幅度提高,但抗压强度随之降低;可再分散性乳胶粉可大幅度提高砂浆的综合性能,适宜掺量为胶凝材料重量的2%-3%。     

干燥进出口温度对EVA可再分散乳胶粉的影响

以聚乙烯醇(PVA)为保护胶体、硅溶胶及无机粉体为抗结块剂,采用喷雾干燥法制备了乙烯-醋酸乙烯酯(EVA)可再分散乳胶粉.讨论了进出口温度对产物性能的影响.试验结果表明:进出口温度对乳胶粉的外观、含水率、流动性、堆积密度、再分散及成膜性能和储存稳定性均有较大的影响;进出口温度升高,乳胶粉含水率降低,流动性提高,堆积密度下降;但进口温度过高,乳胶粉易发生烧结变性;合适的进(出)口温度为150～180℃(72～78℃).FTIR测试结果显示,在进口温度为180℃时进行喷雾干燥,聚合物分子结构未发生明显改变.     

纳米碳酸钙在可再分散聚合物粉末制备中的应用

通过控制适当的工艺参数,采用喷雾干燥法成功制备了VAE类可再分散聚合物粉末.喷雾分散体的粘度为50~300 mPa.s,固含量为40%~45%,热风进口温度为150~200℃,出口温度为60~90℃,雾化器转速为18 000~27 000 r/min.为延长可再分散聚合物粉末的使用年限,以不同粒径的碳酸钙粉末作为抗粘剂进行性能对比,最终选择粒径为10~100 nm的碳酸钙粉末作为抗粘剂,可有效防止聚合物粉末颗粒在常温下重新聚集而结块,且能显著增强可再分散聚合物粉末对水泥砂浆的改性效果.SEM图表明其原因在于纳米碳酸钙颗粒在聚合物颗粒表面形成一层包裹层,且大量分布于聚合物颗粒之间.     

羟基单体对丙烯酸酯聚合物乳液及其乳胶粉性能的影响

通过添加功能单体甲基丙烯酸－β－羟丙酯（HPMA）和甲基丙烯酸（MAA）制备软核硬壳的丙烯酸酯聚合物乳液及其可再分散乳胶粉。重点讨论羟基单体HPMA用量对软核硬壳丙烯酸酯乳液和乳胶粉再分散液的成膜性、再分散稳定性和耐水性等性能的影响。实验结果表明,HPMA添加量为1.2%左右时,在保证再分散稳定性的同时,制备得到的丙烯酸酯原乳液和可再分散乳胶粉的成膜性好,耐水性达到最优;吸光度测试显示HPMA添加量小于等于1.2%时,乳胶粉再分散稳定性好,分散度高达90%,吸光度平均变化小于10%;差示扫描量热（DSC）测试显示丙烯酸酯聚合物乳液胶膜有6 ℃和30 ℃两个玻璃化转变温度（Tg）,乳胶粒子具有软核硬壳结构;扫描光学显微镜（SEM）测试显示原乳液和乳胶粉再分散液成膜性能优异,合成的原乳液在成膜的过程中发生了微相分离,进一步说明合成的乳液具有软核硬壳结构;傅立叶转换红外线光谱（FTIR）显示丙烯酸酯聚合物乳胶粉与原乳液红外谱图基本吻合,说明在一定的干燥条件下,喷雾干燥前后乳胶粒的化学结构不发生明显的变化。     

莲子双螺杆挤压膨化工艺的研究

以莲子为原料,采用双螺杆挤压膨化技术开发莲子膨化食品.研究了原料颗粒大小、原料含水量、进料速度、挤压膨化温度及螺杆转速等因素对莲子膨化的影响.结果表明:当莲子目数大于或等于40目时,莲子膨化较优工艺为:进料速度17～19 r/min,原料含水量14%～16%,膨化温度155～165℃,螺杆转速135～145 r/min.     

内混式两相流喷嘴的雾化特性

利用水和石蜡为介质分别研究内混式两相流喷嘴的流量和雾化特性.两相流喷嘴用水为液相工质研究内混式两相流雾化喷嘴的流量特性,得到内混式两相流喷嘴内气液两相压力、流量的相互影响关系.并利用石蜡和燃料油在温度180℃下性质的相近性,用溶蜡法研究雾化效果的影响因素,通过改变气压、气液质量比研究雾化效果和喷雾场粒径分布的影响规律,为喷嘴的设计和应用提供重要的指导意义.通过研究发现当气液质量比超过0.12时,其对雾化效果的影响趋于稳定,当气相压力达到0.35 MPa后,雾化粒径基本稳定在75～80μm.     

可再分散乳胶粉对粘结砂浆的影响

通过对不同掺量的可再分散乳胶粉对粘结砂浆拉伸粘结强度影响的试验,研究了可再分散乳胶粉对粘结砂浆拉伸粘结强的作用规律,进而确定可再分散乳胶粉在粘结砂浆中的合理掺量区间,为科学合理地使用可再分散乳胶粉提供依据.     

硫铝酸盐水泥基修补砂浆的力学性能

采用可再分散乳胶粉改性硫铝酸盐水泥制备修补砂浆,分别测试其抗折强度、抗压强度、折压比和黏结强度,并结合电子扫描显微镜(SEM)分析水泥砂浆微观结构以及可再分散乳胶粉对硫铝酸盐水泥砂浆的影响机理,研究不同掺量的可再分散乳胶粉对硫铝酸盐水泥砂浆力学性能的影响。试验结果表明:当可再分散乳胶粉质量分数掺量为3%时,水泥砂浆28 d抗折、抗压强度可分别达到8.1 MPa和45.5 MPa,14 d黏结强度可达4.78 MPa;掺入可再分散乳胶粉后,砂浆力学性能改性效果明显。随着可再分散乳胶粉掺量的增加,砂浆的抗折强度大幅度提高,抗压强度降低,折压比增大,黏结强度增大。     

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