Thermal investigation of the phase composition of poly(ethylene terephthalate). Analysis of different methods of determination of the degree of crystallinity of partially crystalline substances

The literature data on the degree of crystallinity of non-deformed poly(ethylene terephthalate) measured at various temperatures have been subjected to comparative analysis. There is no correlation between the results obtained by the different methods. The reason for this is shown to be the imperfections in the methods of determining the degree of crystallinity, which do not provide the true composition of the crystalline phase. Consideration has been paid to the validity of the main principles involved in the thermal method of determining the degree of crystallinity, so as to eliminate the imperfections in the existing methods and to provide the correct value of the mass of the crystalline phase. The phase composition of PET has been analyzed by the thermal method at different temperatures and conditions of crystallization. A marked difference from the literature data is observed in the range of low temperatures.

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Zusammenfassung Eine vergleichende Analyse der Literaturangaben bezüglich des bei verschiedenen Temperaturen gemessenen Kristallisationsgrades von nicht-deformiertem Poly(äthylen-terephthalat) wurde durchgeführt. Zwischen den mit verschiedenen Methoden erhaltenen Ergebnissen besteht keine Korrelation. Es wurde gezeigt, daß der Grund hierfür in der Unvollkommenheit der Methoden zur Bestimmung des Kristallisationsgrades liegt, da diese nicht die wahre Zusammensetzung der Kristallinen Phase angeben. Die Gültigkeit der wichtigsten Prinzipien, welche die thermische Bestimmung des Kristallisationsgrades unter Ausschaltung der Unvollkommenheit der bestehenden Methoden gewährleisten und den richtigen Wert der Masse der kristallinen Phase angeben, wurden in Erwägung gezogen. Die Analyse der Phasenzusammensetzung von PET wurde durch die thermische Methode bei verschiedenen Temperaturen und Kristallisationsbedingungen durchgeführt. Ein deutlicher Unterschied zu den Literaturangaben kann im Bereich der niedrigen Temperaturen beobachtet werden.

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Investigation of thermal decomposition of anthranilates of alkaline earth metals

The thermal properties of calcium, strontium and barium anthranilates (general formula MA₂·n H₂O, whsre M='metal, and) were studied. Thermal, chemical and X-ray analysis, as well as infrared spectra, were used to determine the mechanism of decomposition for these compounds. Calcium anthranilate is decomposed in four stages; the final reaction product is calcium oxide. The other anthranilates are decomposed in three stages; the final reaction products are strontium carbonate and barium carbonate.

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Zusammenfassung Die thermischen Eigenschaften von Kalzium-, Strontium- und Bariumanthranilat (mit der allgemeinen Zusammensetzung MA₂·n H₂O, M=Metall, wurden untersucht.Die Zersetzungsmechanismen dieser Verbindungen wurden durch thermische, chemische- und Röntgenanalyse und mit Infrarotspektroskopie ermittelt. Kalziumanthranilat zersetzt sich in vier Stufen. Das Endprodukt ist Kalziumoxyd. Die anderen Anthranilate zersetzen sich in drei Stufen und geben Strontiumkarbonat und Bariumkarbonat als Endprodukt.

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, MA₂·nH₂O, =, , , . . . .

     

Possibility of thermal analysis of different types of bonding of water in minerals

Various types of water bonding were studied. e.g. water bound by occlusion, by adsorption, by capillary condensation, by chemisorption and as a solid solution, zeolitic water, interlayer water, crystal water and structural water bound in form of hydroxil groups. The differentiation of these various types of bonding is rather difficult, for on heating water is evolved at various temperatures and in rather wide temperature domains which overlap to different extents. Efforts were made to improve the detection by applying the quasi-isothermal quasi-isobaric measuring technique.

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Zusammenfassung Es wurden verschiedene Bindungstypen von Wasser untersucht. Wasser kann unter anderem durch Einschlüsse, Adsorption. Kapillarkondensation, Chemisorption und in Form von Mischkristallen, zeolitisch, schichteingebettetem und Kristallwasser sowie als OH-Form gebunden sein. Die Untersuchung dieser zahlreichen Bindungstypen ist äußerst schwierig, da die Wasserabgabe bei verschiedenen Temperaturen geschieht und die ziemlich breiten Temperaturintervalle mehr oder weniger überlappen. Mittels quasiisothermen und quasiisobaren Meßtechniken wurde versucht, die Möglichkeit der Bestimmung zu verbessern.

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Discrimination of the mechanisms of cooxidation of arylalkanes and alkylamines

Numerical analysis of experimental data on the cooxidation of arylalkanes and alkylamines indicates a chain propagation and interruption mechanism with the participation of amine cation radicals. The steps corresponding to the classical cooxidation mechanism are excessive in this experiment.

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间位基团激发态取代基常数的扩展及应用

合成了七个系列含间位取代基X的二苯乙烯m-XArCH=CHArY-p(简称m-XSBY-p),其中X为NO_2、I、CHCH_2、Ph、Et、NMe_2和CCH。在无水乙醇中测定它们的紫外(UV)吸收光谱,得到紫外吸收最大波长λ_(max)(nm)。对λ_(max)的波数ν_(max)(cm~(-1))进行定量相关,采用曲线拟合方法,得到上述7个间位基团的激发态取代基常数σ_(CC(m))~(ex)。将对位基团和间位基团的σ_(CC)~(ex)与Hammett常数σ进行对比,表明σx_(CC)~(ex)与σ分别表达取代基不同的电子效应。另外,合成了含上述间位基团的二芳基希夫碱(10个)和二苯乙烯(14个),用所得σ_(CC(m))~(ex)预测它们的λ_(max),并用实验测定它们的λ_(max),结果表明预测值与实验值相吻合,验证了所得σ_(CC(m))~(ex)常数的可靠性。收集了225个化合物(涉及二取代苯及二苯乙烯)的ν_(max),建立了一个统一的定量方程来表达这些化合物ν_(max)的变化规律。     

Reactivity and electronic property of decaphenylmetallocenes of Mo and W atoms

The perphenylmetallocene complexes (η⁵-C₅Ph₅)₂W (1), [(η⁵-C₅Ph₅)₂W]⁺I₃⁻ (1⁺I₃), (η⁵-C₅Ph₅)₂Mo (2) and [(η⁵-C₅Ph₅)₂Mo]⁺I₃⁻ (2⁺I₃) have been prepared. Hydrogenation of 1 in THF produces (η⁵-C₅Ph₅)₂WH₂ (4), while (η⁵-C₅Ph₅)₂WHCl (3) is afforded in 1,2-dichloroethane solvent. Carbonylation of 1 produces (η⁵-C₅Ph₅)₂W(CO) (5). Treatment of 1 with the strong acid CF₃SO₃H leads to the dicationic species [(η⁵-C₅Ph₅)₂W]⁺²[CF₃SO₃]⁻₂ (1⁺²Tf₂) after crystallization. The structures of 2⁺I₃ and 1⁺²Tf₂ have been determined by an X-ray diffraction study. The magnetic susceptibility study indicates a ³E_2g ground-state for 1 and 2, and a ⁴A_2g ground-state for 1⁺ and 2⁺.     

Determination of heats of formation of praseodymium antimonides

A systematic investigation of the heats of formation in the Pr-Sb system has been performed using a small-furnace, isoperibolic calorimeter. The compositions and the equilibrium states of the samples have been checked by metallographic and X-ray analyses. The following values have been found for the various compounds (kJ/g atom±2): Pr₂Sb:-99; Pr₅Sb₃:-112; Pr₄Sb₃:-120; PrSb:-126; PrSb₂:-97.The data available (both the results obtained in this work and those already known) are discussed briefly and related to the possible shape of the phase diagram.

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Zusammenfassung Es wurde eine systematische Untersuchung der Bildungswärmen im Pr/Sb-System unter Verwendung eines Kleinofen-Isoperibolkalorimeters ausgeführt. Die Zusammensetzung und der Gleichgewichtszustand der Proben wurden durch metallographische und röntgenographische Analyse ermittelt. Für die einzelnen Verbindungen wurden folgende Werte (kJ·mol^–1 ±2.0) gefunden: Pr₂Sb:-99; Pr₅Sb₃:-112; Pr₄Sb₃:-120;PrSb:-126; PrSb₂:-97. Die als Ergebnis dieser Arbeit erhaltenen und aus der Literatur bereits bekannte Daten werden kurz diskutiert und mit einem möglichen Phasendiagramm in Verbindung gebracht.

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-Sb, . . ( (-)^–1 ±2.0): Pr₂Sb-99; Pr₅Sb₃-112; PrSb₃-120; PrSb-126; PrSb₂-97. .

     

三乙基铝-单烷基磷酸酯催化体系下的环氧丙烷聚合及13C-NMR谱的研究

使用烷基铝-乙酰丙酮-水体系催化环氧化合物的聚合,可得到分子量百万以上的聚合物,Kida采用三异丁基铝-强磷酸-N,N二甲基苯胺体系对环氧化合物进行催化聚合,Wolfe采用三烷基铝一乙酰丙酮-苯基噻唑-水体系对环氧化合物进行催化聚合,Kuran采用连苯三酚-二乙基锌对环氧丙烷进行催化,并且对聚合物作了¹³C-NMR谱的研究,1985年Bovey等研究了聚环氧丙烷的氢谱,确定了聚环氧丙烷各种异构体的构型。     

Explanation of Theoretical Mechanism of Isomerization of L-Alanine Conformation for Experimental Results

B3LYP/6-31＋＋G＊＊ method was applied to investigate the mechanism of alanine isomerization.12 minima and 22 transition states were obtained after optimization and several paths of isomerization were found.It is found that intramolecular single-bond rotation and proton transfer might lead to isomerization.The energy barrier of C–N bond rotation was lower than 2.52 kcal·mol 1,while the energy barrier ranges of the rotation of C–C and C–O were separately 0.43~ 7.01 and 4.69~12.19 kcal·mol 1,and the minimum energy barrier of proton transfer was 30.76 kcal·mol 1.The most probable isomerization path and mechanism for the two most stable conformations was discussed to find that the highest energy barrier to be crossed in this path was 11.87 kcal·mol 1.In order to understand the microscopic nature why only 4 conformations were detected in the experiment,thermodynamic properties of all conformations at the experimental temperature of 391 K was calculated.It is found that conformations XII,XI,X and IX can only unidirectionally convert into conformations rapidly with low energy and vanish immediately.The other conformations were distributed according to Maxwell-Boltzman＇s law,and the distribution probabilities of conformations I,II,III,IV,V,VI,VII and VIII were respectively 27.2%,26.5%,25.8%,6.4%,5.2%,4.8%,2.5% and 1.6%.Conformations I,II and III with bigger probability and stronger absorption peak were easy to detect in the experiment.Conformation IV had a relatively smaller probability（6.4%） and weak absorption peak which,however,could also be identified.The other conformations had too small probability to identify in the spectrum.     

Update of the anharmonic force field parameters of the ozone molecule

A new set of spectroscopic constants of the ¹⁶O₃ molecule (ω_i, x_ij, y_ijk, γ^DD, _i^X, β_ij^X,…), which determine vibrational dependence of band centres and rotational parameters, is derived from recent accurate analysis of high-resolution experimental ro-vibrational spectra through the theoretical approach based on second-order perturbation expansions in normal coordinates accounting for Darling–Dennison resonance interactions. These values are used to update empirical values of anharmonic coefficients (k_ijl, k_ijlm) of the potential function expansion in normal coordinates. Quadratic f_rr, f_r, f_rr′, f as well as cubic f_rst and quartic f_rstl force constants in internal (bond lengths, bond angle) coordinates are also derived. A detailed discussion is devoted to the accuracy of parameter determination for each of four steps of calculations. It is emphasised that the conventional method based on the inversion of formulae of the perturbation theory gives the largest uncertainties at the last step of calculations: the determination of the anharmonic force field in internal coordinates.     

Nature of extended defects of CuO

For the first time, using high-resolution electron microscopy, extended defects (twins, screw dislocations and microdistortions) of disperse CuO have been found. Their structure is described.

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CuO -, .

     

Observation of textures of nematic polymers and estimation of the elastic constants

The texture of a copolyesteramide, Vectra® B950, has been studied by optical microscopy. At rest, the defects are typical of a biaxial nematic phase, but under the influence of a magnetic field or under shear, the nematic transforms into a uniaxial phase. The Freedericksz geometry yields a K₁ elastic constant of the order of 10^-8 N. The diffusivities K_III/_n and K_II/_n are obtained by measuring the light intensity transmitted through a sample during shear start-up and relaxation, and from this we estimate K_III ≅ 10 ^-9N and K_II ≅ 10 ^-10N. Since the biaxiality is small, these uniaxial constants adequately describe the phase at rest.     

Synthesis and characterization of new oligosilane derivatives of iron and molybdenum

By use of salt elimination, the transition metal substituted oligosilanes (η⁵-C₅Me₄Et)Fe(CO)₂SiMe₂SiMe₂Cl 1, (η⁵-C₅Me₄Et)Mo(CO)₃SiMe₂SiMe₂Br 2, (η⁵-C₅Me₄Et)Fe(CO)₂(SiMe₂)₆(CO)₂Fe(η⁵-C₅Me₄Et) 3 and (η⁵-C₅Me₄Et)Fe(CO)₂(SiMe₂)₆Br 4 were prepared and characterized. Compound 1 is well crystallized from pentane and its structure has been determined by X-ray diffraction analysis.