聚苯硫醚/尼龙6共混物界面对结晶行为的影响

高分子作为材料时 ,其力学性能受其结晶形态的影响 ,而其结晶形态与其结晶行为有关 .结晶性聚合物共混物中结晶组分由于第二组分存在 ,改变了结晶组分在熔体时的化学与物理环境 .因此 ,其结晶组分的结晶行为不仅取决于两组分在熔体时的相容性 ,而且与第二组分是否起到异相晶核作用和 /或两组分间界面是否诱导成核作用有关 ,从而影响共混物中结晶组分的结晶行为 ,导致共混物力学性能的改变[1～ 4] .在ＰＰＳ/ＰＡ6共混物中 ,由于ＰＰＳ的熔点和熔体结晶温度都比ＰＡ6的高 ,共混物熔体降温结晶ＰＰＳ是在ＰＡ6熔体存在下发生结晶 ,而ＰＡ6是在…     

动态硫化EPDM／PP共混体系中PP相的结晶度及晶体结构的研究

研究了动态硫化ＥＰＤＭ／ＰＰ共混物中ＰＰ相的结晶度及晶体结构,同时讨论了制备工艺条件以共混物中ＰＰ相的结晶度和晶体结构的影响。结果表明：在动态硫化ＥＰＤＭ／ＰＰ共混物中,硫化的ＥＰＤＭ的分子键没有穿入ＰＰ的晶区,ＰＰ的结晶度随ＥＰＤＭ含量的增加而下降。提高共混温度,加入软化剂或碳黑均使共混物中ＰＰ的结晶度降低,共混时间１５ｍｉｎ时,共混物中ＰＰ相的结晶度最低,但ＰＰ的晶格不受制备工艺条件的影响。     

聚丙烯／顺丁橡胶动态硫化增韧的研究

研究了在聚丙烯(pp)与顺丁橡胶(BR)共混过程中加入橡胶硫化剂使共混体系中橡胶相动态硫化交联。研究结果表明,采用动态硫化法可提高共混物的冲击强度和拉伸强度。借助于SEM和DMA,证实了动态硫化使PP/BR共混体系具有相界面粘结良好的多相结构,改善了两相相容性。探讨了动态硫化增韧的机理。     

聚醚醚酮/聚醚醚酮酮共混体系的熔融和等温结晶行为

采用熔融共混方法制备了聚醚醚酮和聚醚醚酮酮的共混物,用DSC对共混物的熔融行为和等温结晶行为进行了研究.结果表明,共混物熔点随聚醚醚酮含量增加而降低,但与聚醚醚酮酮有相同的平衡熔点,二者共混没有改变其结晶的成核与生长机制.     

低乙烯含量聚丙烯共聚物结晶成核剂研究

利用ＤＳＣ和偏光显微镜等手段研究了部分成核剂对聚丙烯均聚物（ＰＰ）、低乙烯含量聚丙烯共聚物及聚丙烯／聚乙烯（ＰＰ／ＰＥ）共混物结晶行为的影响，结果表明所用成核剂对ＰＰ和改性ＰＰ具有一定的普适性。聚丙烯共聚物中，由于链结构规整性变差，成核剂的作用显得特别突出，而ＰＰ／ＰＥ共混物中，由于成核剂向ＰＥ相迁移而使其对ＰＰ结晶的成核效率降低。     

轻质碳酸钙／聚丙烯共混物中聚丙烯β－晶的成核结晶研究

用Ｘ射线衍射和差示扫描量热法研究了轻质碳酸钙／聚丙烯共混物（Ｌ－ＣａＣＯ３／ＰＰ）中ＰＰβ－晶的成核结晶现象，发现ＰＰβ－晶的成核结晶与ＰＰ的来源和Ｌ－ＣａＣＯ３在共混物中的含量有关，铝酸酯偶联剂对共混体系的ＰＰβ－晶的成核结晶有显著的增强作用．分析认为共混物中ＰＰβ－晶的成核结晶现象是ＰＰ中存在的某些杂质（主要是催化剂残余物）与Ｌ－ＣａＣＯ３组成的复合成核剂作用的结果，而铝酸酯是这种复合成核剂的一种促进剂．     

轻质碳酸钙／聚丙烯共混物中聚丙烯β—晶的成核结晶研究

用Ｘ射线衍射和差示扫描量热法研究了轻质碳酸钙／聚丙烯共混物（Ｌ－ＣａＣＯ３／ＰＰ）中ＰＰβ－晶的成核结晶现象，发现ＰＰβ－晶的成核结晶与ＰＰ的来源和Ｌ－ＣａＣＯ３在共混物中的含量有关，铝酸酯偶联剂对共混体系的ＰＰβ－晶的成核结晶有显著的增强作用。分析认为共混物中ＰＰβ－晶的成核结晶现象是ＰＰ中存在的某些杂质（主要是催化剂残余物）与Ｌ－ＣａＣＯ３组成的复合成核剂作用的结果，而铝酸酯是这种复合成核剂的     

结晶／结晶共混体系PPS／PEEK中PPS组分的结晶熔融行为（Ⅱ）──熔融条件对退火样品的影响

结晶／结晶共混体系ＰＰＳ／ＰＥＥＫ中ＰＰＳ组分的结晶熔融行为（Ⅱ）──熔融条件对退火样品的影响麦堪成，许家瑞，梅震，曾汉民（广州中山大学材料科学研究所，广州，５１０２７５）关键词聚苯硫醚，聚醚醚酮，结晶熔融行为，熔融双峰聚苯硫醚（ＰＰＳ）的结晶熔融行...     

四臂聚乳酸/线性聚乳酸共混物的结晶行为及机理研究

为了探究四臂聚乳酸对线性聚乳酸结晶行为的影响,将四臂聚乳酸与线性聚乳酸的共混物在示差扫描量热仪(DSC)和偏振光显微镜(PLM)热台中加热到熔点附近的不同温度下恒温后分别进行了降温—升温程序,考察了四臂聚乳酸对线性聚乳酸的结晶行为的影响.结果表明,随着四臂聚乳酸含量增加,四臂聚乳酸在共混物形成的晶体中的比例增大且四臂聚乳酸有促进共混物晶体完善的作用,导致了熔融过程中熔点的上升.进一步研究证明,在共混物中完全熔融的四臂聚乳酸的支化结构能够促进结晶成核点的形成,从而促进四臂聚乳酸/线性聚乳酸共混物的结晶;而部分熔融的四臂聚乳酸能大幅促进共混物的结晶能力,这是未完全熔融的晶体的成核作用所导致的.     

侧链液晶离聚物对PA1010/PP共混体系的增容作用

将聚酰胺（PA1010）、聚丙烯（PP）和热致型侧链液晶离聚物（SLCI）进行熔融共混，采用FTIR，SEM，DSC，WAXD研究测定了共混物中的相互作用，用形态结构，热行为和结晶行为，系统地研究了SLCI对PA101／PP共混物的增容作用。结果表明，SLCI有效地改善了PA1010／PP共混物的形态结构，增强了PA1010与PP链间的相互作用，使PA1010／PP熔点升高，结晶度提高。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.