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1.
采用氢氧化锂作引发剂,N,N-二甲基甲酰胺作促进剂,八甲基环四硅氧烷,八苯基环四硅氧烷及四甲基-四乙烯基环四硅氧烷作单体,合成了聚二甲基-二苯基硅氧烷与聚二甲基-甲基乙烯基硅氧烷形成的AB嵌段共聚物,研究了氢氧化锂的用量及反应时间对反应的影响,并且用^1HNMR,IR,UV谱及特性粘数对嵌段聚合物进行了表征。  相似文献   

2.
采用氢氧化锂作引发剂,N,N-二甲基甲酰胺(DMF)作促进剂,八甲基环四硅氧烷(D_4)》、八苯基环四硅氧烷(P_4)及四甲基—四乙烯基环四硅氧烷(V_4)作单体,合成了聚二甲基—二苯基硅氧烷(A)与聚二甲基—甲基乙烯基硅氧烷(B)形成的AB嵌段共聚物,研究了氢氧化锂的用量及反应时间对反应的影响,并且用HNMR、IR、UV谱及特性粘数对嵌段聚合物进行了表征。同时采取逐步沉降分级的方法,给出了分子量分布。  相似文献   

3.
合成了一类有机硅嵌段齐聚物α,ω-双(γ-氨基)聚二甲基二苯基硅氧烷(APMPS),并以此为嵌段与聚酰亚胺(PI)硬段进行嵌段共聚,得到一系列不同软段含量的多嵌段共聚物(APMPS-b-PI)。通过热重分析(TGA)和力学性能测试,证明该嵌段共聚物具有优良的热稳定性及抗张强度。  相似文献   

4.
利用酚羟基封端的聚砜和二氯封端、含Si-H功能键的硅氧烷低聚体合成交替偶联嵌段共聚物。由于Si-H键在碱性介质中不稳定,二氯封端的聚硅氢烷被选作嵌段基元.所得聚合物用IR、H ̄1NMR、GPC和TEM作了表征,结果表明嵌段合成是成功的.通过Si-H键与烯键的加成反应在该共聚物的分子链上引入了碱性侧基而得到一系列嵌段型高分子配体.  相似文献   

5.
倍半硅氧烷催化剂八聚(四甲基铵)硅酸盐催化八甲基环四硅氧烷开环聚合,以1,3-二乙烯基-1,1,3,3-四甲基二硅氧烷为封端剂,制备了聚倍半硅氧烷为核的八臂星型乙烯基硅油,系统研究了封端剂用量、聚合时间、聚合反应温度和反应溶剂等对聚合反应的影响规律.结果表明,在无溶剂状态下100℃聚合6 h,可获得分子量5.2×104的聚倍半硅氧烷为核的八臂星型乙烯基硅油.此后,将所得聚倍半硅氧烷为核的八臂星型乙烯基硅油与乙烯基MQ树脂、二甲基含氢硅油和铂络合物混合制备了高透明的加成型硅橡胶,研究了硅橡胶的机械力学性能,还尝试着将其用作发光二极管(LED)封装材料.当乙烯基MQ树脂用量为八臂星型乙烯基硅油质量分数的30%,Karstedt’s铂催化剂用量为硅橡胶总质量的0.1%,硅氢与硅乙烯基摩尔比1∶1时,硅橡胶经100℃固化2 h,其硬度约40 Shore A,在可见光范围内透光率高于90%,用该加成型硅橡胶封装的LED具有较高的光效,较窄的色温分布.  相似文献   

6.
研究了乙烯基封端聚甲基三氟丙基-二甲基硅氧烷共聚物的合成方法,讨论了合成反应中催化剂用量对聚合反应的影响,制备出不同粘度乙烯基封端氟硅油,并以此为主体材料制备了高温硫化氟硅混炼橡胶.实验结果表明,该橡胶有较好的耐油性能.  相似文献   

7.
使用甲基纤维素和六甲基二硅胺烷(HMDS)合成了三甲基硅基甲基纤维素醚(TMS—MC).通过溶液浇铸制备了TMS—MC膜和TMS—MC与一种钴Schiff碱络合物,N,N’-二水杨乙二亚氨基钴的复合膜.对复合膜的力学性能、富氧性能以及影响富氧性能的因素如压差、温度以及络合物的用量进行了研究.与TMS—MC膜相比,复合膜由于钴络合物的加入具有对氧的促进输送作用,因此获得在低压差条件下透氧系数和氧氮分离系数同时提高的效果,尤其是后者较为显著.在20℃和0.05MPa压差条件下,透氧系数为57.86Barter,氧氮分离系数达到11.08.  相似文献   

8.
本文以4,4′-二氟二苯酮、4,4′-双-(4-氯苯基磺酰基)朕苯和对苯二酚为单体通过溶液缩聚合成了聚芳醚酮砜共聚物系列样品,并用IR,DSC,TGA,WAXD等手段对共聚物进行表征.结果表明,由于两种双卤单体活性不同,在缩聚反应中所形成的其聚物分子链为无规嵌段结构;该共聚物随着醚醚砜砜重复单元含量增加由结晶性高聚物转变为非结晶高聚物,共聚物具有很好的耐高温性能.  相似文献   

9.
在甲苯中,甲基二氯硅烷与氨气反应,生成甲基硅氨烷,它在氨基基钠催化下,聚合成聚硅烷。1200℃下将聚硅氮烷进行高温热裂解,生成了以Si3N4为主的材料。材料在950℃热失重分析中失重0.069%,呈现很好的耐热性,还用IR、UV和^1h-nmr对基硅氮烷作了分析。  相似文献   

10.
聚合物应力应变特性与其应变过程聚集态演化密切相关,而有关应变诱发聚合物结晶研究多集中在均聚物与聚酯方面.以3,3-二叠氮甲基氧丁环(BAMO)和四氢呋喃(THF)等摩尔比准理想无规共聚醚端羟基3,3-二叠氮甲基氧丁环-四氢呋喃预聚物(PBT)为研究对象,利用氨基甲酸酯反应制备了末端三维交联PBT弹性体.变温力学性能测试表明PBT弹性体拉伸强度和延伸率由60℃时0.72 MPa,72%升至-40℃时16.2 MPa,740%,拉伸强度和延伸率随温度下降而单调上升;低于-20℃时弹性体拉伸强度和延伸率随温度下降迅速增加.理论分析表明,-40℃时弹性体网链沿应变方向取向,网链中BAMO微嵌段在应变320%处诱发结晶,增强分子链间相互作用,提高了PBT弹性体力学性能.定应变循环拉伸测试表明,PBT弹性体拉伸强度随循环次数增加而逐渐下降,低温、高应变下的拉伸强度高度依赖于弹性体拉伸前的有效网链密度.   相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

14.
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.  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
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-  相似文献   

19.
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-  相似文献   

20.
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  相似文献   

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