钼改性高邻位酚醛纤维的制备及性能

通过正交试验得出钼改性高邻位酚醛树脂(o-MoPR)的最佳合成工艺参数,并制得了重均分子质量为4 255g/mol的o-MoPR,采用熔融纺丝进一步交联处理制得了钼改性高邻位酚醛纤维(oMoPF).对制得的钼改性高邻位酚醛树脂及其纤维进行了结构性能表征,发现钼元素已连接到酚醛树脂的分子链中.研究获得了熔融纺丝初生酚醛纤维的最佳交联浴升温速率为25℃/h,最佳热处理温度为170℃.研究发现钼改性和高邻位化可使酚醛纤维的力学性能和热性能得到较大提高.o-MoPF的拉伸强度比常规酚醛纤维(PF)提升了21 MPa,达到了185 MPa,o-MoPF在N2气氛中的初始分解温度达到535℃,800℃残余质量分数为78%,分别比PF提高了123℃和33%.     

钼酚醛树脂热分解动力学的研究

用热重法TG分析了钼酚醛树脂的热分解动力学。实验结果表明：固化剂六亚甲基四胺与钼酚醛树脂配比为10／100时，钼酚醛树脂的热失重率最低，同时热分解温度最高；钼酚醛树脂的热分解反应为一级反应，热分解活化能为137．5kJ／mol，500℃时热分解速率常数为9．83^＊10^4s^-1。     

热固性钼酚醛树脂的合成工艺研究

针对普通酚醛树脂(PF)作为耐火材料结合剂使用中存在的问题，研究了以钼酸改性PF的可行性。由苯酚和甲醛先合成羟甲基苯酚，再用钼酸与羟甲基经酯化反应得到一种新型的热固性钼PF。通过正交试验与结果分析，讨论各因素对合成工艺的影响，并确定了最佳的工艺参数，在n(苯酚)：n(甲醛)：n(H2MoO4)：n(NaOH)=1：1．3：0．06：0．15，反应温度为90℃，反应时间为1h的条件下合成的钼PF残碳率可达56．31％，比一般热固性PF的残碳率高出13个百分点。表明它是比较理想的耐火材料用结合剂。     

不同硼含量硼改性酚醛树脂的合成及其性能

采用特定的合成工艺合成了不同硼含量的改性酚醛树脂，并利用傅里叶红外光谱、热重分析和冲击试验等方法对其性能进行了分析．结果表明：合成出了不同硼含量的改性酚醛树脂，通过红外吸收峰对比法和计算法对比确定了硼含量，合成的硼改性酚醛树脂硼的最高质量分数可达9．0％；硼改性酚醛树脂的耐热性随硼含量的增加而提高，高硼含量的样品在1200℃时的失重率仅为34．7％，残炭率高达65．3％；硼的引入提高了酚醛树脂的韧性．随着硼含量的增加，改性酚醛树脂的冲击韧性提高，但当硼质量分数过高时（9．0％），其冲击韧性有所下降．     

二步法合成酚醛树脂结合剂的研究

采用二步法合成工艺合成了甲阶酚醛树脂,研究了醛酚摩尔比、催化荆品种对酚醛树脂残碳量的影响。当采用碱金属碳酸盐作催化剂;醛酚摩尔比为1．35～1．37时;树脂具有最高的残碳量。采用最优化工艺合成的液体酚醛树脂残碳量达到49％。与一步法合成工艺相比,残碳量提高4～5％,抗氧化温度提高40～50℃。由此合成的结合剂适用于含碳耐火材料的制造。     

硼改性酚醛树脂的合成及其热性能研究

通过合成性能优于传统酚醛树脂的新型酚醛树脂以满足国内工业、机械制造业飞速发展的配套需要.主要研究硼改性酚醛树脂的特定合成工艺,并与传统热固性酚醛树脂进行比较,研究催化剂用量、酚醛比、硼酸加入量等因素对硼改性酚醛树脂性能的影响.并通过红外光谱和热重分析仪等分析手段对硼改性酚醛树脂的结构和热性能进行表征.实验结果表明:合成硼改性酚醛树脂的最佳反应条件为n(甲醛)∶n(苯酚)∶n(硼酸)=1.4∶1∶0.4,氢氧化钠用量为苯酚质量的3%,第一阶段反应时间为1.5h,反应温度为60℃,第二阶段反应时间为1.5h,反应温度为90℃,在该条件下合成的硼改性酚醛树脂的残碳率为71.07%,远高于传统酚醛树脂的残碳率48.48%.     

高邻位热塑性酚醛树脂的合成与表征

改变传统合成工艺,在无催化剂条件下,合成了无金属杂质的高邻位热塑性酚醛树脂.考察了原料种类、反应压力、反应温度等因素对树脂性能的影响。并通过软化点测试仪、核磁共振谱仪、TG-DSC热分析等,研究酚醛树脂合成过程中各种制备参数对酚醛树脂结构和性能的影响。结果表明:反应原料中水分子含量越高,产物的稳定性越好;缩聚反应温度在210℃时,反应1.5h后,缩聚反应完全进行。     

两种合成工艺下酚醛树脂结构与性能比较

在粘度相近。最终摩尔比相同的条件下,采用两种不同的工艺合成酚醛树脂,并对两种工艺下合成的酚醛树脂的性能进行了分析比较。结果表明由热塑性树脂出发制备的酚醛树脂的游离醛降低,固化时间增加,胶合强度降低;通过13C—NMR对其结构进行了分析比较,结果表明常规工艺制备的酚醛树脂的羟甲基含量高于由热塑性树脂出发制备的酚醛树脂,同时邻对位比值高于由热塑性树脂出发制备的酚醛树脂.     

高性能酚醛复合材料工艺研究及应用

用桐油和纳米SiO_2对酚醛树脂进行改性,合成品质优良的树脂,根据桐油加入工艺条件,探讨其合成改性机理。采用热分析系统,对桐油/酚醛和纳米SiO_2/桐油/酚醛两种改性树脂进行了测试,通过对TG/DTA曲线研究,展示了它们的热解动态。结果表明它们的耐热性均显著优于普通的酚醛树脂,样品初始热分解温度在420℃以上。桐油改性的酚醛树脂,具有优良的醇溶性,柔韧性,使合成更易于控制,对产业化具有重要意义。制成摩擦制动材料,测试了其摩擦性能。     

改性线性酚醛树脂的合成

针对线性酚醛树脂用于油田防砂作业存在的缺陷，用“CH2OCHCH2C1”和“NH2CH2CH2CH2Si(OEt)3”对线性酚醛树脂进行接枝改性，合成出具有两种活性基团的新型预聚合改性酚醛树脂．实验表明，改性线性酚醛树脂固砂的热性能和抗压强度均有明显提高，热降解起始温度提高了60℃～80℃，抗压强度平均提高了4．5MPa。     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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