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1.
聚芳基乙炔树脂/杉木粉木材陶瓷的制备与表征 总被引:1,自引:0,他引:1
用聚芳基乙炔树脂浸渍杉木粉,固化制得聚芳基乙炔/杉木粉复合材料,经高温炭化得到了一种新型木材陶瓷。 用DTG分析了聚芳基乙炔树脂和复合材料的热稳定性,用XRD、LRS和SEM研究了炭化温度和树脂用量对木材陶瓷物相构成、断面微孔形态和抗压强度的影响。 结果表明,木材陶瓷呈三维多孔结构,孔分布比较均匀;复合材料保持了很高的热分解温度(325 ℃)和残碳率(70%)。 随着炭化温度升高,d002晶面间距由0.3895 nm减小至0.3530 nm,而微晶尺寸Lc和La有不同程度增加。 木材陶瓷的开孔率随炭化温度的升高由31.5%减小至20.1%,而抗压强度由3.0 MPa增大至6.2 MPa。 树脂/杉木粉质量比对木材陶瓷的微孔尺寸和形状有较大影响,但对石墨微晶尺寸影响不明显。 相似文献
2.
聚醚酯嵌段共聚物熔体的流变性能 总被引:11,自引:1,他引:10
采用毛细管流变仪测定了组成比、聚醚分子量、熔融时间和熔融温度对嵌段聚醚酯熔体表观粘度的影响.结果发现在所研究的温度和切变速率范围内,该结构聚醚酯熔体为假塑性非牛顿流体,其粘度随聚酯段含量的增加而增加,随熔融时间增加而降低,随聚醚分子量的增大而增大.聚醚酯的零切粘度可由Spencer Dillon 公式外推得到,零切粘度对温度的依赖关系服从Andrade 公式. 相似文献
3.
利用十六烷基罗丹明B作为主要荧光探针,研究了水溶性嵌段共聚物PluronicF-68在水溶液中的胶束化行为.研究表明:PluronicF-68形成胶束的临界胶束浓度与温度有极大关系,随温度的升高,其CMC值急剧下降,并且温度对胶束的性质也有很大影响,温度升高可导致胶束的微观粘度增大,表现出很强的负粘-温效应,并发现引起这种负粘-温效应的主要原因是PluronicF-68分子中聚环氧乙烷(PEO)链随温度升高亲水性变差引起其收缩所致,而由聚环氧丙烷(PPO)形成的内核的微观粘度随温度的升高略有下降. 相似文献
4.
γ-Mo2N催化剂上的乙炔选择加氢 总被引:14,自引:1,他引:13
采用固定床连续流动反应器对γ-Mo2N催化剂上的乙炔加氢反应进行了研究.在150℃的反应温度下,乙炔的转化率为95%,乙烯的选择性达到80%,乙烷和丁烯的选择性分别为4%和10%.反应温度和空速的变化对反应产物的选择性没有明显的影响.在同样的反应条件下,钯催化剂上乙炔加氢反应的主要产物是乙烷,产物组成随反应温度和空速的变化而变化.对γ-Mo2N上的乙炔选择加氢生成乙烯的机制进行了解释,认为γ-Mo2N表面上滞留的强吸附的碳氢物种可能有利于乙炔高选择性地生成乙烯. 相似文献
5.
微波复合直流等离子体转化天然气制乙炔的研究 总被引:4,自引:0,他引:4
利用微波复合直流等离子体对天然气转化制乙炔反应进行了研究. 考察了氢烷比、气体流量、功率等参数对装置的能量利用率以及天然气转化反应的影响, 并考核了微波复合直流等离子体转化天然气制乙炔工艺的稳定性. 实验结果表明: 微波复合直流等离子体装置的能量利用率随等离子体工作气体的流量的增加而提高; 由于微波的作用使传统直流柱状等离子体分化为多根丝状等离子体, 从而使得电极的烧蚀方式由传统的点烧蚀变为面烧蚀, 并大幅度提高等离子体转化天然气工艺的稳定性和电极寿命; 甲烷的转化率和乙炔的收率随功率的增加而提高, 随CH4/H2比和气体流量的增加而降低, 在氢烷比为0.9、总气体流量为760 L/min、微波源输出电功率6 kW、直流电源输出功率90 kW时, 甲烷转化率可达84.4%, 乙炔选择性为75.6%, 乙炔收率为63.8%, 乙炔能耗达10.8 kWh•kg-1; 电极寿命超过200 h. 相似文献
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7.
本文通过测定不同浓度的溶液在不同温度和切变速率下的粘度,讨论了氰乙基纤维素/二甲基甲酰胺溶液的流变行为。溶液的流动曲线表明,该溶液是一种假塑性液体。在浓度较高时,存在屈服现象,屈服应力的大小与浓度和温度有关。溶液的浓度—粘度曲线表示出典型的液晶行为。粘度与浓度的关系和屈服应力与浓度的关系相似。溶液的临界浓度随温度的升高而增加。在单相区(各向同性相或液晶相),粘度随温度升高而降低,表观流动活化能大于零。但在两相区,粘度随温度的升高而增大,表观流动活化能小于零。该实验得到的临界浓度与通过光学的方法所得的临界浓度是一致的。 相似文献
8.
在303.15 K、313.15 K、323.15 K、333.15 K温度下,0-6 MPa压力范围内测定了甲烷在水-叔丁醇混合溶剂中的溶解度.溶剂中叔丁醇的摩尔分数(x_(TBA))从0到1.结果表明,在温度和溶剂组成一定条件下,甲烷的溶解度随其分区的增加而增大,随x_(TBA)的增加,在富水区内,甲烷的溶解度变化较缓慢,当x_(TBA)超过某值时,甲烷的溶解度随x_(TBA)的增加而增大,并且幅度较大;在x_(TBA)约为0-0.045范围内,甲烷的溶解度随温度增加而减小,x_(TBA)约在0.045-0.15范围内,溶解度随温度增加而增加,x_(TBA)约在0.15~1.0范围内,溶解度随温度增加而减小.根据溶解度与温度和溶剂组成的关系可以推测,在303.15-333.15 K、0-6 MPa范围内,水-叙丁醇混合溶剂中仍存在笼合物结构.根据溶解度与温度、压力的关系讨论了甲烷在此混合溶剂中的亨利常数、偏摩尔体积、标准溶解自由能、标准溶解焓和标准溶解熵. 相似文献
9.
含氰基离子液体的合成、表征及流变性质研究 总被引:1,自引:1,他引:0
摘要合成、 表征了一系列新的含氰基咪唑类离子液体. 测定了该离子液体的密度、 熔点及溶解性等物理性质, 研究了其在稳态、 瞬态和动态条件下的流变行为. 结果表明, 当剪切速率在0.1~50 s-1范围内时, 其粘度不随剪切速率的变化而变化, 但随温度升高而降低, 粘流活化能随取代基长度变化呈现规律性变化. 对于1-丁基-3-氰乙基咪唑六氟磷酸盐离子液体, 维持剪切速率不变时, 其剪切应力和粘度均不随时间变化, 且随着温度的升高而降低; 在动态条件下, 在线性粘弹区, 复合粘度和损耗模量G″ 随温度升高而降低.
关键词 相似文献
10.
四芳基取代环戊二烯酮与二氟取代二苯乙炔通过Diels-Alder环加成反应制得六芳基取代苯(6);6在路易斯酸催化下通过Scholl环氧化脱氢反应合成了一个新型的氟取代六苯并蔻衍生物———1,3,5,8,10,12,14,17-八氟代六苯并蔻(7),收率70%,其结构经1H NMR,13C NMR和MS表征。TG研究结果表明,7失重5%的温度为452℃。 相似文献
11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
12.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
13.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
14.
Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
15.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
16.
N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
17.
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
18.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献
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20.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献