芳香聚醚酮酮晶体结构及其晶型变化的研究（Ⅰ）

利用Ｘ射线及热分析技术研究了聚醚酮酮（ＰＥＫＫ）的溶剂诱导结晶及从玻璃态结晶和从熔融态结晶的行为。发现ＰＥＫＫ有两种晶型结构（Ⅰ和Ⅱ），晶型Ⅱ的形成与热历史和溶剂诱导有关，其熔点始终低于Ⅰ型１０℃左右。ＰＥＫＫ的低温熔融峰与其分子链极化有关，而与热历史无关，此低温熔融峰热焓占总热焓２％～１０％，其平衡熔点为４０９℃。     

含间位取代苯基聚醚酮酮的结晶与晶体结构研究

通过差示扫描法（ＤＳＣ）及广角Ｘ 射线衍射（ＷＡＸＤ）技术研究了含间位取代苯基聚醚酮酮（ＰＥＫｍＫ）的结晶行为与晶体结构．Ｘ 射线结果表明，从熔融态及玻璃态结晶时，ＰＥＫｍＫ只有一种晶型，其晶胞参数为：ａ＝０７６７２ｎｍ，ｂ＝０６１４９ｎｍ，ｃ＝１５９９ｎｍ．ＤＳＣ结果表明，ＰＥＫｍＫ热分析曲线都出现了熔融双峰，低熔融峰（ＤＯＷｎ）热焓占总热焓４～７％，它源于初始结晶形成的同一晶型不同厚度片晶．低熔融峰在２５０℃以上结晶转化成高熔融峰（Ｉ），ＰＥＫｍＫ平衡熔点为２９５℃     

聚乳酸可降解材料结晶和熔融行为的研究

用DSC和XRD研究了聚乙二醇（PEG）用量、分子量和退火温度对PLA结晶和熔融行为的影响。结果表明PEG的加入有利提高PLA的结晶度和结晶温度;PLA／PEG样品在低于10022退火后均表现出双熔融峰特征,退火温度越高,样品的低熔融峰（Tm1）越高且熔融热焓也越高;PEG分子量越大,其低熔融峰的熔融热焓（△H1）越大...     

HE－1型催化剂异相聚合乙烯结晶性能研究 Ⅱ．超高分子量PE结晶行为

用小角Ｘ－射线散射，广角Ｘ－射线衍射，差示扫描量热法，研究了ＨＥ－１型钛系催化剂异相聚合超高分子量聚乙烯的稀溶液的结晶和熔融结晶的熔点，熔化热，结晶度，长周期，晶区厚度和非晶区厚度随分子量与结晶温度的关系，并着重讨论了熔融结晶和初生态结晶的不同过程机理，结果表明：ＵＨＭＷＰＥ稀溶液结晶的结晶度（Ｘ％），长周期（Ｌ）和晶区厚度（Ｌｃ）与分子量Ｍｗ无关，随结晶温度升高而增加，非晶区厚度（Ｌａ）与分子量     

纳米碳酸钙及其表面处理对等规聚丙烯结晶行为的影响

应用差示扫描量热方法研究了不同表面改性碳酸钙纳米粒子对聚丙烯 (PP)等温与非等温结晶动力学的影响 ,并研究了上述各聚丙烯结晶样品的熔融行为和晶型 .研究发现纳米碳酸钙具有明显的成核效应 ,并具有较强的诱导 β 型结晶的能力 ,而且与粒子的表面处理密切相关 .     

含能材料HMX-RDX的热行为研究

采用差示扫描量热法研究了含能材料1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷-环三甲撑三硝胺(HMX-RDX)的热行为。结果表明,当m(HMX)∶m(RDX)=25∶75时HMX和RDX达到了共熔。随着RDX含量的增加,HMX-RDX的晶型转变温度有所升高,晶型转化的热焓逐渐减少,共熔热焓却随之增加,共熔温度基本保持不变。     

聚乳酸-聚乙二醇单甲醚共混体系的调制DSC分析

采用调制差示扫描量热法(MDSC)研究了聚乳酸(PLA)与聚乙二醇单甲醚(MPEG)共混体系的热性能。研究结果表明,MDSC可有效分辨PLA重结晶和熔融的重叠效应,在测试条件下,PLA的α’-α晶型转变与α晶体的熔融几乎同时进行。随着升温速率的加快和调制周期的延长,当增塑剂的质量分数为15%时,PLA-MPEG共混物分割在不可逆曲线的重结晶焓逐渐升高(最高约28J/g),熔融焓逐渐降低(最低约为3.3J/g);分割在可逆曲线的熔融峰逐渐由多重峰变为单峰,且焓变值逐渐升高(最高约66.1J/g),相应的可逆曲线熔融分割比例达到了95.2%。通过提高升温速率和延长调制周期,可使大部分熔融分割在可逆曲线上,但过快的升温速率和过长的调制周期会导致PLA相转变时的周期数过少,DSC调制功能的分辨率下降,设置测试条件时需综合考虑。     

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。     

聚己内酯-天然骨粉生物医用复合材料的制备和性能

采用熔融共混法制备了不同天然骨粉含量的聚己内酯-天然骨粉（PCL-BP）生物医用复合材料,并通过力学实验、表面亲水性分析、差示扫描量热分析和热重分析对复合材料的性能进行了表征。结果表明：随着天然骨粉含量的增加,复合材料的拉伸和弯曲强度先增加后降低,其表面亲水性得以改善。此外,复合材料的结晶温度升高,熔融焓降低,热稳定性...     

成核剂对聚丙烯熔融行为的影响

成核剂对聚丙烯熔融行为的影响陈彦徐懋（中国科学院化学研究所高分子物理开放实验室北京１０００８０）关键词成核剂，聚丙烯，平衡熔点聚合物的熔融过程受分子量大小、分子量分布、分子链构型（等规度、分子结构单元的键接序列）、不同的结晶晶型、不同的热历史等...     

不同结晶度的乙二醇及其水溶液玻璃化转变与焓松弛

为了考察晶体成分对无定形成分玻璃化转变和结构松弛行为的影响,利用差示扫描量热法(DSC),结合低温显微技术,研究了乙二醇(EG)及其50％水溶液在不同结晶度时的玻璃化转变和焓松弛行为.采用等温结晶方法控制骤冷的部分结晶玻璃体中的晶体份额.DSC结果表明,对于部分结晶的EG,只有单一的玻璃化转变过程,而对于50％EG,当结晶度不同时,不同程度地表现出两次玻璃化转变（无定形相Ⅰ和无定形相Ⅱ）.相Ⅰ的玻璃化转变温度和完全无定形态的含水EG的玻璃化转变温度相一致;相Ⅱ的玻璃化转变温度要比此温度约高6 ℃.低温显微观察结果印证了DSC实验结果.DSC等温退火的实验和KWW(Kohlrausch-Williams-Watts)衰变函数分析结果表明,EG无定形和50％EG中的两种无定形有不同的焓松弛行为.     

Enthalpy of sublimation in the study of the solid state of organic compounds. Application to erythritol and threitol

The enthalpies of sublimation of erythritol and L-threitol have been determined at 298.15 K by calorimetry. The values obtained for the two diastereomers differ from one another by 17 kJ mol(-1). An interpretation of these results is based on the decomposition of this thermodynamic property in a term coming from the intermolecular interactions of the molecules in the crystal (delta(int)H degrees) and another one related with the conformational change of the molecules on going from the crystal lattice to the most stable forms in the gas phase (delta(conf)H degrees). This last term was calculated from the values of the enthalpy of the molecules in the gas state and of the enthalpy of the isolated molecules with the crystal conformation. Both quantities were obtained by density functional theory (DFT) calculations at the B3LYP/6-311G++(d,p) level of theory. The results obtained in this study show that the most important contribution to the differences observed in the enthalpy of sublimation are the differences in the enthalpy of conformational change (13 kJ mol(-1)) rather than different intermolecular forces exhibited in the solid phase. This is explained by the lower enthalpy of threitol in the gas phase relative to erythritol, which is attributed to the higher strength of the intramolecular hydrogen bonds in the former. The comparison of the calculated infrared spectra obtained for the two compounds in the gas phase supports this interpretation.     

The Thermodynamic Parameters of Sorption and Selectivity of Chiral Nematic Liquid Crystals of Terephthalidene-bis-2-methylbutyl para-Aminobenzoate

The thermodynamic characteristics of sorption of n-alkanes, arenes, aldehydes, monoatomic alcohols, and isomeric forms of butanediol-2,3 by chiral nematic liquid crystals, terephthalidene-bis-2-methylbutyl para-aminobenzoate, were studied over the temperature range of the existence of the meso- and isotropic phases. The contributions of dipole—dipole and specific interactions to the enthalpy of sorption were estimated. Sorbate—liquid crystal systems were characterized by positive deviations from ideality caused by the enthalpy factor. The mesophase of the liquid crystal studied was found to possess selectivity with respect to the optical isomers of butanediol-2,3 (α_R/S = 1.03 over the temperature range 140–150°C). It was shown that diol–liquid crystal molecular H-complexes formed played an important role in the mechanism of chiral recognition of butanediol-2,3 optical isomers under gas-liquid chromatography conditions.     

原油加剂降凝的研究

采用高温气相色谱分析了越南、阿曼和大庆原油中蜡的碳数及分布组成,采用偏光显微镜观察了不同蜡含量原油的蜡晶形态变化时,分析了蜡结晶过程中的结构、分布状态和生长规律与不同原油组成的关系,得出了蜡结晶过程与原油组成之间的变化规律。结合采用X射线衍射仪和DSC差示扫描量热仪对自制聚合物(MOA)的结晶度和热性能的分析测试,表明原油中蜡晶结构与聚合物的结晶度密切相关,结晶度变化时,蜡晶分散效果有所区别,两者匹配状态时分散效果最佳,体系的粘温特性研究也证明了这一点。同时,降凝剂使得系统的热性能——溶解焓和溶解熵均发生了改变,原油中石蜡的熔程变长,相变能变大。     

Metal ion complexes of antivirally active nucleotide analogues. Conclusions regarding their biological action

Acyclic nucleoside phosphonates (ANPs), i.e., analogues of (2'-deoxy)nucleoside 5'-monophosphates, have been studied during the past 15 years for their potential as antiviral drugs. One of these compounds, 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA; Adefovir) was recently approved in the form of its bis(pivaloyloxymethyl)ester (Adefovir dipivoxil) for use in hepatitis B therapy, a disease evoked by a DNA virus. Diphosphorylated PMEA(2-), i.e., PMEApp(4-), is initially recognized by nucleic acid polymerases as an excellent substrate, but after insertion in the growing nucleic acid chain, this is terminated due to the lack of a 3'-hydroxy group. Based on the metal ion-binding properties of PMEApp(4-) it can be explained why the ether oxygen in the aliphatic chain, R-CH(2)-O-CH(2)-PO(3)pp(4-), is compulsory for a useful biological activity. Consequently, this critical review presents an overview on the coordination chemistry of various ANPs and correlates this to their biological properties.     

Thermodynamic analysis of the immersion of a smectite substituted with Na or Ca: heat effect due to the cation

The enthalpy produced during immersion in water of a smectite, identified as a montmorillonite, substituted by Ca or Na is analyzed using three different approaches. The heat of immersion is measured using the classical calorimetric method. It is compared to an estimate using adsorption techniques. And it is calculated from a theoretical estimate of the surface energy of a crystal model of montmorillonite. The comparison of the different values allows the enthalpy linked to the swelling phenomenon to be estimated. The Ca form appears in every case to interact more strongly with water molecules than the Na form.     

Glass transition and enthalpy relaxation of ethylene glycol and its aqueous solution

Differential scanning calorimetry (DSC) and cryomicroscopy were employed to investigate the glass transition and enthalpy relaxation behaviors of ethylene glycol (EG) and its aqueous solution (50% EG) with different crystallization percent. Isothermal crystallization method was used in devitrification region to get different crystallinity after samples quenched below glass transition temperature. The DSC thermograms upon warming showed that the pure EG has a single glass transition, while the 50% EG solution has two if the solution crystallized partially. It is believed that the lower temperature transition represents the glass transition of bulk amorphous phase of EG aqueous solution glass state, while the higher one is related to ice inclusions, whose mobility is restricted by ice crystal. Cryomicroscopic observation indicated that the EG crystal has regular shape while the ice crystal in 50% EG aqueous solution glass matrix has no regular surface. Isothermal annealing experiments at temperatures lower than T_g were also conducted on these amorphous samples in DSC, and the results showed that both the two amorphous phases presented in 50% EG experience enthalpy relaxation. The relaxation process of restricted amorphous phase is more sensitive to annealing temperature.     

Phase behaviour and morphology of polymer/liquid crystal blends

Abstract

The phase behaviour of blends of poly(ethylene oxide) (PEO) with the liquid crystal p-azoxyanisole (PAA) has been studied by differential scanning calorimetry and optical microscopy. This system exhibits partial miscibility of the components in the molten state (at temperatures above 337 K). The melting temperature and enthalpy of the PAA phase has been found to depend on the blend composition, whereas the melting behaviour of the polymer phase remains quite unaltered. The occurrence of the PAA nematic phase, dispersed within an isotropic liquid phase, has been observed at high concentrations of liquid crystal. The morphology of the blends in the solid state changes largely with the PAA content, depending on the solubility of the components in the liquid phase.     

Calorimetric investigation of phase transitions in cholesteryl oleate

An adiabatic scanning calorimeter has been used to investigate the temperature dependence of the enthalpy and the heat capacity near phase transitions in the cholesteric liquid crystal cholesteryl oleate (CO). It is found that the blue phases in CO are thermodynamically stable and that the observed enthalpy differences between the phases are small.     

Calorimetric investigation of phase transitions in cholesteryl oleate

An adiabatic scanning calorimeter has been used to investigate the temperature dependence of the enthalpy and the heat capacity near phase transitions in the cholesteric liquid crystal cholesteryl oleate (CO). It is found that the blue phases in CO are thermodynamically stable and that the observed enthalpy differences between the phases are small.