Analysis of Calorimetric Curves Detected During the Polymorphic Transformation of Isotactic Polybutene-1

Multiple endotherms detected on heating melt-crystallized i-polybutene-1(PBu-1) are associated to the polymorphic transformation from the tetragonal (Form II) to the hexagonal modification (Form I). During this transformation, a progressive increase of the intensity of the high temperature endotherm, at the expenses of that pertaining to the low temperature one, is observed in DSC heating curves. Depending on molecular characteristics of the constituent chains and crystallization conditions, the two endotherms may exhibit some extent of superposition. In these cases, a reliable procedure to analyze the whole thermal curve must be found and adopted in order to follow the progress of the transformation in quantitative terms. The same set of thermal curves, detected after various ageing times of melt-crystallized i-PBu-1, has been analyzed according to four different approaches. Comparison of the results shows that, with the exception of the analysis based on the ‘partial area’ routine, available to most instruments, all methods lead to equivalent results. The simplest approach, based on the mass balance during structural transformation, should be preferred whenever constant overall degree of crystallinity can be assumed throughout the whole process. This revised version was published online in July 2006 with corrections to the Cover Date.     

等规聚丙烯/聚丁烯-1釜内合金的结构与性能

高分子材料的组成、 组分分布及链结构与宏观性能紧密相关. 因此, 分析多组分釜内合金材料的链结构特点与性能之间的关系至关重要. 采用升温淋洗分级的方法对两种采用序贯两段聚合原位合成的等规聚丙烯/聚丁烯-1(iPP/iPB)釜内合金在-30 ℃~140 ℃温度范围进行分级, 采用核磁共振波谱仪、 傅里叶变换红外光谱仪、 差示扫描量热仪和凝胶渗透色谱仪等表征了级分的链结构及序列分布、 热行为、 分子量(M_w)及分子量分布(M_w/M_n)等. 结果表明iPP/iPB合金主要由5种级分组成, 高等规聚丁烯(iPB)为主要组分, 同时含有少量的丁烯-丙烯嵌段共聚物(PB-b-PP)和等规聚丙烯(iPP)等. 随淋洗温度升高, PB-b-PP级分中PP嵌段长度逐渐增加, PB嵌段长度逐渐减小; 在相同的淋洗温度, 合金B的嵌段共聚物级分中PP嵌段较长且结晶较完善; 合金B中iPB组分及嵌段共聚物组分含量较高, 使得合金B具有较高的拉伸强度、 弯曲强度、 优异的抗冲击性能、 较高的维卡软化温度及较快的晶型转变速率.     

聚丁烯-1制备研究进展

等规立构聚丁烯-1是结晶型聚合物,具有突出的耐热抗蠕变性,优异的韧性、耐环境应力开裂性、耐磨性、耐燃性和优良的可加工性、环保性等,特别适合于制备管材。本文对近年来聚丁烯-1的制备研究状况进行了综述,主要介绍了Ziegler-Natta催化体系中给电子体、其它相关反应条件对聚丁烯-1结构的影响,同时介绍了相关催化剂的一般制备方法。介绍不同结构茂金属对聚丁烯-1结构的影响。针对我国聚丁烯-1研究现状和发展前景提出研究开发聚丁烯-1树脂等新材料应用具有重要的社会和经济意义。     

高等规聚丁烯-1合成工艺研究进展

高等规聚丁烯-1以其优异的综合性能,得到了日益广泛的关注和研究。从催化剂体系出发,本文评述了合成高等规聚丁烯-1的Ziegler-Natta催化剂体系和茂金属催化剂体系的催化剂组成及其催化丁烯-1聚合的催化特征,综述了合成高等规聚丁烯-1的聚合工艺,包括淤浆法、液相本体法(均相和非均相)和气相法,详细介绍了三种聚合工艺的特点,并重点介绍了液相本体法合成高等规聚丁烯-1的工艺优缺点,指明了今后高等规聚丁烯-1合成工艺的发展趋势。     

Solvent vapor annealing induced polymorphic transformation of polybutene-1

Solvent annealing is a facile method for changing the aggregated microstructure and physical properties of polymer materials. In this paper, we addressed the effects of solvent vapor annealing, including chloroform and water vapor, on the polymorphic transformation in both hot-pressed film and electrospun nonwoven of isotactic polybutene-1 (PB-1) by means of in situ Fourier transform infrared spectroscopy (FTIR). The pretty rapid transition rate caused by the increased motion of molecular chains under chloroform vapor is associated with a lowest crystallinity. Also, a decreased crystallinity with the crystal transition occurred in electrospun nonwovens resulting from the relaxation of the stretched molecular chains into amorphous state rather than realignment into crystal form I predominating the crystal transition process.     

新型单茂钛/改性甲基铝氧烷催化剂合成立构多嵌段聚丁烯-1

茂金属聚烯烃以其高附加值而受到广泛重视.有关桥联或非桥联二茂基金属催化剂用于合成无规、等规、间规聚丙烯和聚丁烯-1已有报道.Llinas等用rac-Et(CpMe₄Ind)·TiCl₂和甲基铝氧烷(MAO)催化剂合成了等规/无规立构嵌.     

Linear viscoelastic behaviors of polybutene-1 melts with various structure parameters

The effects of weight-average molecular(Mw), molecular weight distribution(MWD), and isotacticity on the linear viscoelastic behavior of polybutene-1 melts are studied. It is observed that the linear viscoelastic region becomes slightly narrower with increasing frequency. In frequency sweeps, the transition of the polymer melts flow from Newtonian flow to power-law flow can be observed. The melts with higher Mw and/or broader MWD, as well as higher isotacticity exhibit higher complex viscosity, zero shear viscosity, viscoelasticity moduli, relaxation modulus, broader transition zone, while lower critical shear rate, non-Newtonian index, and the frequency at which elasticity begins to play an important role. The relationship of zero shear viscosity on Mw has been established, which agrees with the classical power law. Furthermore, it is found that the cross-over frequency decreases with increasing Mw and the cross-over modulus increases with narrowing MWD.     

Strain-Controlled Tensile Deformation Behavior and Relaxation Properties of Isotactic Poly(1-butene) and Its Ethylene Copolymers

The tensile deformation behaviour of poly(1-butene) and two of its ethylene copoloymers was studied at room temperature. This was done by investigating true stress-strain curves at constant strain rates, elastic recovery and stress relaxation properties and in-situ WAXS patterns during the deformation process. As for a series of semicrystalline polymers in previous studies, a strain-controlled deformation behaviour was found. The differential compliance, the recovery properties and the stress relaxation curves changed simultaneously at well-defined points. The strains at which these points occurred along the true stress-strain remained constant for the different samples despite their different percentage crystallinities. The well-defined way in which the different samples respond to external stresses complies with the granular substructure of the crystalline lamellae in a semicrystalline polymer.     

无定型二氧化硅在硅沸石表面上的固相转化

无定型二氧化硅在硅沸石表面上的固相转化龙英才（复旦大学化学系，上海，２００４３３）关键词硅沸石，固相转化，无定型二氧化硅硅沸石（Ｓｉｌｉｃａｌｉｔｅ－１）的晶体结构与ＺＳＭ－５相同，由于其疏水／亲有机物的独特吸附特性作为一种新型沸石吸附剂有广泛的应用...     

Metal-ion-dependent,Solvent-mediated Structural Transformation and Simultaneous Partial Transmetalation of an srs Framework into Desulfurization-efficient Co-Cu-HKUST-1

[Co₂(BTC)(Cl)(DMA)₃] ( 1 ) (BTC^3– = benzene-1,3,5-tricarboxylate, DMA = N,N-dimethylacetamide) obtained from the reaction between Co²⁺ and H₃BTC in DMA features a three-dimensional srs framework built of 3-connected {Co₂(COO)₃} as secondary building units and BTC^3– as spacers. When exposed to DMA solution of Cu(NO₃)₂, 1 was progressively transformed into the first heterometallic Co-Cu-HKUST-1 ([Co_0.14Cu_2.86(BTC)₂]) ( 2 ) of such kind via unusually solvent-mediated structural transformation and simultaneous partial transmetalation. While the mechanism for such conversion is proposed based on systematic studies, 2 was revealed to be an equally efficient desulfurization adsorbent as the homometallic Cu-HKUST-1 in removing thiophene (0.142 mmol S per gram of adsorbent). However, when exposed to Zn(NO₃)₂ solution in DMA for longer time, 1 retained its framework with limited metal-ion exchange, resulting in the formation of [Co_1.93Zn_0.07(BTC)(Cl)(DMA)₃] ( 3 ). Possible reasons responsible for the formation of 2 and 3 through different routes could be due to the less solubility and more thermodynamic stability of 2 in comparison with those of 1 , and the different coordination geometries which Co²⁺, Zn²⁺ and Cu²⁺ prefer.     

基于HPLC-HRMS/MS~n/QqQ技术的人参皂苷Rb_1化学转化产物的结构与途径分析

利用液相色谱-质谱联用技术分析了Keggin型12-磷钨酸化学转化人参皂苷Rb1产物的结构与转化途径.基于高效液相色谱对转化产物的快速分离,利用Q Exactive高分辨质谱的Full MS-AIF模式快速鉴定了产物结构,并利用多级串联质谱进行结构验证.进一步结合人参皂苷异构体在反向C18色谱柱上的相对保留时间,快速分析鉴定出Rb1的10种转化产物为20(S)-Rg3,20(R)-Rg3,20(S)-25-OH-Rg3,20(R)-25-OH-Rg3,25-OH-Rk1,25-OH-Rg5,Rg5,Rk1,(20S,25)-环氧-Rg3和(20R,25)-环氧-Rg3.根据转化产物的结构初步推断了人参皂苷的转化途径:在12-磷钨酸产生的酸性环境中,Rb1主要通过C20位去糖基化、差向异构化和烯烃链的水合、消除及环合反应转化为稀有皂苷.采用三重四极杆质谱的选择反应监测模式准确定量分析了Rb1的转化效率和稀有皂苷20(S)-Rg3,20(R)-Rg3,Rk1和Rg5的产率.定量分析结果显示,与生物转化相比,12-磷钨酸对Rb1有更高的转化效率,反应40 min后转化率达到100%.本文结果表明,HPLC-HRMS/MSn/Qq Q技术是人参皂苷等天然产物结构解析与定量分析的有效方法.     

卤取代对三氮系1-3H原子转移互变异构影响的理论研究

用量子化学从头计算方法研究了卤取代对三氮系1-3H原子转移互变异构的影响,探讨卤取代对降低反应活化能和稳定N＝N双键的电子效应.对反应机理作出解释.     

Transformation of Ginsenosides Rg1 and Rb1, and Crude Sanchi Saponins by Human Intestinal Microflora

Fractions major in ginsenosides Rg₁ and Rb₁ from Sanchi saponins were transformed by human fecal flora. This study yielded the corresponding aglycone, protopanaxatriol, in 49.4% from Rg₁, protopanaxadiol 20‐O‐glucoside in 54.8% from Rb₁, and dihydroprotopanaxadiol 20‐O‐glucoside in 87.6% from dihydro Rb₁, by incubation with healthy feces for 70 h in subgram level. Never the less large‐scale incubation of crude Sanchi saponins revealed the complete biotransformation of Rb₁ and the almost unchanged Rg₁. A small amount of Rg₁ was found to be converted into 20 R‐ginsenoside Rh₁ and its dehydration product, 20(22) Z‐ginsenoside Rh₄.     

聚萘胺膜与金属离子的络合及催化特性的研究

系统研究了聚萘胺膜与Ａｇ、Ｈｇ（２＋）等十余种金属离子的络合特性。以循环伏安法、交流阻抗分析等方法研究了Ａｇ－ＰＮＡ电极对抗坏血酸（Ｈ２Ａ）氧化的催化作用，提出了电极反应的可能机理。Ａｇ－ＰＮＡ电极可用于测定试样中的Ｈ２Ａ含量。     

Electrostatic Interaction and Reaction Behavior of a 1, 2,4‐Triazole Mixture with Dinitrobenzene

The electrostatic interactions between gas generating agent and organic electron withdrawing additives were studied to understand how the interaction affects the reactions of their thermal behavior. To explore the electronic interaction and its effect, the thermal behavior of a mixture of dinitrobenzene isomers [p‐dinitrobenzene (pDNB) and m‐dinitrobenzene (mDNB)] and 1, 2,4‐triazole (TA) was analyzed. Density functional calculations and electron density analysis proved that both pDNB and mDNB in a 1:1 ratio withdraw electrons from TA. The analysis of pyrolysis behavior showed that TA and dinitrobenzene mixtures (TA/pDNB or TA/mDNB) react at lower temperatures than each precursor. Gas chromatography mass analysis and UV/Vis spectroscopy showed reasonable results that suggested that pDNB and TA make condensed products in the initial stage of the reaction according to the differential scanning calorimetry measurement. When the mixtures were ignited under pressurized conditions, TA/pDNB burned easily while TA/mDNB burned only partially. These results suggested that the interaction between triazole and dinitrobenzene affects the pyrolysis and combustion behavior of a TA/dinitrobenzene mixture.     

基于超高效液相色谱-飞行时间质谱法测定LAMTOR1在肝脏炎症恶性转化中调控的代谢物

LAMTOR1(晚期胞内体/溶酶体接头蛋白,MAPK以及mTOR激活蛋白1)是机体应对营养压力时重要的调控蛋白之一.公共开放基因表达数据库分析显示LAMTOR1在非酒精性脂肪肝炎(NASH)和肝癌中均异常高表达,显示LAMTOR1在NASH和肝癌发生发展中发挥重要作用,探索LAMTOR1在肝脏炎症恶性转化过程中调控的代...     

Different Behavior of 2-Substituted 3-Nitro-2H-chromenes in the Reaction with Stabilized Azomethine Ylides Generated from α-Iminoesters

The AgOAc-catalysed reaction of 3-nitro-2-phenyl-2H-chromenes with stabilized azomethine ylides generated from the imines based on methyl glycinate and arylaldehydes leads to a mixture of endo and endo’ isomers of the corresponding chromeno[3,4-c]pyrrolidines in a ratio of 2.0–2.3:1 in 85–93% total yields as a result of a Michael addition/Mannich reaction sequence. In a similar reaction involving 2-trifluoromethyl-3-nitro-2H-chromenes, only endo chromeno[3,4-c]pyrrolidines are formed in 85–94% yields. 3-Nitro-2-(trichloromethyl)-2H-chromenes under the same conditions react with these azomethine ylides to give the corresponding Michael adducts as individual anti-isomers with the cis,trans-configuration of the chromane ring in 40–67% yields. Some 4-CF₃-substituted chromano[3,4-c]pyrrolidines exhibited high cytotoxic activity against HeLa human cervical carcinoma cells.     

Complete 1H and 13C signal assignment of prenol‐10 with 3D NMR spectroscopy

The complete assignment of ¹H and ¹³C chemical shifts of natural abundance prenol‐10 is reported for the first time. It was achieved using 3D NMR experiments, which were based on random sampling of the evolution time space followed by multidimensional Fourier transform. This approach makes it possible to acquire 3D NMR spectra in a reasonable time and preserves high resolution in indirectly detected dimensions. It is shown that the interpretation of 3D COSY–HMBC and 3D TOCSY–HSQC spectra is crucial in the structural analysis of prenol‐10. Copyright © 2009 John Wiley & Sons, Ltd.     

Copolymerization of ethylene and 1-butene with highly active Ticl4/THF/Mgcl2, Ticl4/THF/Mgcl2/SiO2, and TiCl3.1/3AlCl3 catalysts

Highly active catalysts for copolymerization have been prepared by the precipitation of MgCl₂/ToCl₄ complex with or without high surface area silica. Copolymerization of ethylene and 1-butene has been tested by using the prepared catalysts at various concentrations of 1-butene. The catalytic activities are 20–80 kg/g Ti h. The rate of copolymerization is strongly affected by the addition of 1-butene. The decay rate of copolymerization is first order with respect to time. Analyses of copolymers with solvent extraction, DSC, IR, XRD, and NMR were performed. Ethylene reactivity ratio (k₁₁) for TiCl₄/MgCl₂/THF catalyst is calculated to be about 26 by NMR spectrum. © 1994 John Wiley & Sons, Inc.