含间苯基聚醚醚酮酮的合成与性能研究

含间苯基聚醚醚酮酮的合成与性能研究林权，王一凡，张万金，吴忠文，尹玖梅（吉林大学化学系，长春，１３００２３）（中国科学院长春应用化学研究所）关键词聚醚醚酮酮，间苯基，熔点，玻璃化转变温度聚芳醚酮类高聚物具有优异的热、电、机械性能．全对苯基位聚醚醚酮酮...     

PBT／PET共混体系的熔融行为

用差示扫描量热法（ＤＳＣ）考察了ＰＢＴ／ＰＥＴ共混体系的结晶熔融行为，在共混体系中两组份的结晶熔上均随着含量的减小而下降，熔点下降既有形结构变化因素，又有因两组份相容而引起的热力学因素。熔融热焓△Ｈｍ的变化与两组份结晶熔点的变化有相似的规律。这些结果说明在共混体系中ＰＥＴ、ＰＢＴ两组份在结晶一熔融过程中存在相互协同作用，同时也说明ＰＢＴ、ＰＥＴ两组份是晶相分离的，而非晶区是相混容的。     

Crystallisation, melting, recrystallisation and polymorphism of n-eicosane for application as a phase change material

Phase change materials (PCM) provide thermoregulation originating from the latent heat exchanged during melting or crystallisation. Linear hydrocarbons have weak interactions, but high symmetry, providing an effective quantity of latent heat over the most acceptable temperature range for applications. The ability to both melt and crystallise over a narrow range is made complex by nucleation, polymorphism and the kinetic nature of these changes. Differential scanning calorimetry (DSC), optical microscopy and temperature modulated DSC (TMDSC) was used to study the melting of n-eicosane. This PCM has a low degree of supercooling and conversion to the most stable crystalline state (triclinic) that occurs rapidly from a metastable phase (rotator) state on cooling. TMDSC revealed a small, yet similar degree of thermodynamic reversibility in the melting of each of the crystalline phases.     

热致性液晶嵌段共聚酯的合成及表征

以对羟基苯甲酸甲酯和乙二醇为原料，通过熔融酯交换反应合成中间体（Ⅰ）：双（对一羟基苯甲酸）乙二醇酯．用溶液缩合法合成了三种不同嵌段长度的液晶嵌段共聚酯（Ｐ２４７、Ｐ２７７、Ｐ２７４）作为液晶聚合物与热塑性聚合物的“增容剂”．ＦＴＩＲ，Ｈ ＮＭＲ分析表明，嵌段共聚酯的结构和组成与分子设计基本相符；偏光显微镜证实，嵌段共聚酯在一定温度范围内为热致性向列型液晶，在较低温度为均相，在较高温度为两相结构．     

SYNTHESIS AND CHARACTERIZATION OF AROMATIC LIQUID CRYSTALLINE COPOLYESTERS WITH REGULAR SEQUENCE STRUCTURE

Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Sehotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage, thermal analysis and X-ray diffraction were used to investigate the structure and properties of the copolyesters. The effects of structural units, such as flexible spacer, noncolinear meta-linked phenylene unit, crankshaft unit, kink with flexible bridging unit and various substituted benzene rings on melting temperature of aromatic copolyesters were studied and discussed on the basis of crystalline structure of the polymers.     

Stabilization of DNA duplexes by covalently-linked peptides

The hybridization properties of various peptide-oligonucleotide hybrids were assessed from UV thermal denaturation experiments. Analysis of these and other published data suggests that peptide chains, both hydrophobic and positively charged, generally have a clear stabilizing effect on short-chain oligonucleotide duplexes.     

一类2(1H)-喹喔啉化合物的裂解机理

用电子轰击质谱（EI-MS）研究了一类喹喔啉化合物；1-烷基-3-甲基-2（1H）-喹喔啉-2-酮（1-alkyl-3-methyl-2(1H)-quinoxalin-2-one，简称AMQ，其中alky1=H,CH3，C2H5，n-C3H7，n-C5H11；结果表明随着烷基链的增长，样品熔点通常会有所降低，结合在电子轰击下所产生的裂解碎片离子，并根据其结构特征为乙基化样品为代表，推导了该类化合物在电子轰击作用下可能发生的裂解机理。     

Characterization, crystallization kinetics and melting behavior of poly(ethylene succinate-co-21 mol% trimethylene succinate) copolyester

A copolyester was synthesized and characterized to have 78.6 mol% ethylene succinate unit and 21.4 mol% trimethylene succinate unit by using NMR. The value of the random parameter is 0.97 that can be considered to be a random copolymer. The melting behavior after isothermal crystallization was studied using differential scanning calorimeter by varying the crystallization temperature, the heating rate and the crystallization time. Triple melting peaks were observed. The melting behavior indicates that the upper melting peaks are primarily due to the melting of lamellar crystals with different stability. The Hoffman-Weeks linear plot gives an equilibrium melting temperature of 94.0 °C. The spherulite growth of this copolyester from 72 °C to 30 or 15 °C at a cooling rate of 1 or 2 °C/min was monitored and recorded using an optical microscope equipped with a CCD camera and a DVD recorder. These experiments including the self-nucleation pretreatment took 72 min and 60 min, respectively. Continuous growth rates between melting and glass transition temperatures can be obtained after curve-fitting procedures. These data fit well with those data points measured in the isothermal experiments, which is time consuming. These isothermal and continuous data were separately analyzed with the Hoffman and Lauritzen theory. A regime II-III transition was detected at about 51.5 ± 0.1 °C.     

Melting of polymers by non-isothermal, temperature-modulated calorimetry: analysis of various irreversible latent heat contributions to the reversing heat capacity

This paper provides an analysis of contributions to the apparent, reversing heat capacity when measured by temperature-modulated differential scanning analysis (TMDSC) with an underlying heating rate in the temperature range where irreversible transitions with latent heats occur. To deconvolute the data of a TMDSC scan into a total and reversing part, it is common practice to use the sliding averages and the first harmonics of the Fourier series of temperature and heat-flow rate. Under certain conditions, this procedure produces erroneous reversing contributions which are detailed by experiment and simulation. Unless the response to the temperature modulation is linear, the total heat-flow rate is stationary, and the transition is truly reversible and occurs only once during the temperature scan, one cannot expect a true deconvolution of total and reversible effects. In the presence of multiple, irreversible transitions within a modulation period, however, each process involving latent heat can increase the modulation amplitude, as demonstrated by computer-simulation of polymer melting. As a result, the multiple transitions may give erroneously high latent heats when integrating the apparent reversing heat capacity with respect to temperature.     

Scanning microcalorimetry at high cooling rate

Heat capacity measurements at fast cooling and heating were realized for linear polyethylene NBS SRM (standard reference material) 1484 sample, ca. 120 ng, in the melting-crystallization region. A commercial vacuum sensor, thermal conductivity gauge TCG-3880, Xensor Integrations, was utilized as a cell for a micro-calorimeter suitable for such measurements. The cell consists of a thin-film Si₃N_x membrane with a film-thermopile and a film-heater, which are formed at the membrane center. The current at the heater as well as the signal from the thermopile were monitored in real time during fast scanning of temperature of the central part of the membrane. The measurements were performed in an ambient gas, so that controlled cooling and heating rates up to 5×10³ K/s were achieved. As conditions were not adiabatic, the heat leakage from the sample was calibrated and was taken into account for heat capacity measurements. A simple calibration algorithm was developed for such measurements. Thus, a step towards ultra fast cooling scanning calorimetry was made.