Li2O﹒2B2O3-H2O过饱和溶液20℃结晶动力学研究

盐水溶液中存在过饱和现象，硼酸盐溶液的过饱和即是一例．其中，镁础酸盐体系过饱和溶液在不同浓度和温度条件下的液固相关系曾有多次报道［‘－’］；给出过许多有益的结果，也探讨了镁硼酸盐的结晶反应机理并拟合出相应的结晶动力学方程．这些工作对认识盐水溶液过饱和现象有重要意义．为了更广泛地认识和了解不同棚酸盐水溶液中的过饱和现象，本文采用动力学方法，首先对Li20·2B203－HZO过饱和溶液结晶过程进行了研究．1实验初始反应溶液中Li。O／BZO。（摩尔比）为1／2，按此配比计算并称取需要量的Li0H·H。O（A．R．）、H。…     

聚乙二醇对振荡反应的影响

前文［1］曾指出，生物体系的化学振荡反应实际上是产生于水溶胶之中（包括高分子溶液及表面活性剂溶液）．作为反应介质，水溶胶对生物体系的周期现象有着不可忽略的重要作用．因此，要模拟生物体系的化学振荡就不能不考虑溶胶对振荡反应的影响．前文［2，3］报道了表面活性剂TritonX－100（简称TX－100），TritonX－305等对振荡反应的影响．为了解聚乙二醇类表面活性剂中EO链的作用及高分子溶液对振荡反应的特征影响，我们选用高分子聚乙二醇（PEG）作为添加剂，考虑由于它的加入而引起振荡反应的变化．为了减少PEG中自由羟基的还原…     

胶束溶液中同步荧光法测定苯并［a］芘的研究

在不同胶束溶液中考察了苯并［ａ］芘（Ｂ［ａ］Ｐ）的同步荧光光谱。结果表明，在十二烷基苯磺酸钠（ＳＤＢＳ）胶束溶液中，Ｂ［ａ］Ｐ的检测限可达０．００９３ｎｇ／ｍＬ，方法相对标准偏差为１．７％。用于实际水样的测定，结果满意。     

碲(Ⅳ)-碘化钾-罗丹明B体系荧光猝灭反应测定痕量碲

在高浓度碘化钾溶液中，碲（Ⅳ）与Ｉ－形成［ＴｅＩ８］４－配阴离子，［ＴｅＩ８］４－再与罗丹明Ｂ 形成离子缔合络合物［ＲｈＢ］４［ＴｅＩ８］，使罗丹明Ｂ溶液的荧光明显猝灭。反应适宜介质为０．６０ ～１．００ ｍｏｌ／Ｌ的磷酸溶液；线性范围为 ０～１６μｇ／Ｌ碲；反应有高灵敏度，对于碲的检测限为 ０·９１ μｇ／Ｌ，方法也有较好选择性，可用于某些样品中碲的测定。     

胶束溶液中同步荧光法测定苯半[a]芘的研究

在不同胶束溶液中考察了苯并［ａ］芘（Ｂ［ａ］Ｐ）的同步荧光光谱。结果表明，在十二烷基苯磺酸钠胶束溶液中，Ｂ［ａ］Ｐ的检测限可达０．００９３ｎｇ／ｍＬ，方法相对标准偏差为１．７％。用于实际水样的测定，结果满意。     

“浓度对Fe(SCN)_3生成平衡的影响”实验的改进和剖析

高中《化学》第三册（选修）实验１－４［１］和新编高中《化学》（试验本）第二册（Ⅱ）实验 ３－１［２］是浓度对化学平衡影响的实验。依教材所述方法进行演示，观察到的现象（指让全体学生平视观察所看到的现象，下同）是：０．０１ｍｏｌ／Ｌ ＦｅＣ１３溶液和 ０． ０１ｍｏｌ／Ｌ ＫＳＣＮ溶液等体积混合后的溶液中，补加少量１ｍｏｌ／ＬＦｅＣ１３溶液，颜色加深不明显；而若补加相同量的１ｍｏｌ／Ｌ ＫＳＣＮ溶液，颜色加深特别明显。为什么会有这样大的差别？笔者提出如下分析，并对实验做出改进，供同行参考。１补加 ＦｅＣ１…     

从氨性柠檬酸溶液中电沉积Ni-Mo的机理研究

含钼大于约27％（质量分数）Ni－Mo合金，具有较高的耐蚀性，特别是在盐酸和硫酸溶液中，其耐蚀性优于SUS304不锈钢［1］．因此，人们对该种合金的电沉积进行了广泛的研究［1－4］．对合金共沉积机理也作了一定的研究．一般认为，钼不能单独进行电沉积，但它可以同铁族元素共沉积［5］．对钼与铁族元素的共沉积机理，人们已提出了几种假设．一般认为［3］，钼可能是多步还原，即六价钼首先被电化学还原成低价钼化合物，而后由吸附在诱导金属（铁族元素）上的原子氢进一步还原成合金中的零价钼，为了进一步弄清Ni－Mo合金的共沉积机理，本…     

KBPh4从水到直链一元醇中的标准迁移自由能

四苯硼钠（NaBPh4）与四苯硼钾（KBPh4）均属典型的大阴离子强电解质，并且具有相似的分子结构和相同的晶型［1］，但二者在溶液中的热力学行为却明显不同，为了系统和定量地研究二者在相同溶剂中热力学性质的差别，本文继前文［2］对KBPh4从水到7种直链一元醇中的标准迁移自由能进行研究．1实验部分1．1仪器与试剂UV－365型分光光度计（日本岛津制作所）；CS501型超级恒温槽（重庆实验设备厂）．NaBPh4和所用醇溶剂及提纯方法同前文［2］；KCl（S·P）；KBPh4是通过NaBPh4水溶液与过量5％的KCI水溶液反应而得，产物先经水洗涤…     

刚性聚芳醚腈合成与性能研究

用２，６ 二氟苯甲腈和间苯二酚为原料，在碱性条件下，于非质子极性溶剂中，通过溶液高温缩聚法制备聚芳醚腈［Ｐｏｌｙ（ｃｙａｎｏａｒｙｌｅｔｈｅｒ）ＰＣＥ］．并用ＩＲ、ＤＳＣ、ＴＧ、ＷＡＸＤ等手段对其结构及热性能、结晶行为进行了研究．结果表明，ＰＣＥ高聚物不仅具备较好的耐高温和耐热老化性能，而且具有较好的结晶性能．同时，用对比的方法，对ＰＣＥ的晶体结构进行了初步的探讨．     

现场表面拉曼光谱研究Ni-P合金电沉积机理

由于Ｎｉ Ｐ合金具有许多优越的物理和化学性能 ,如高的耐蚀性［１］、好的电催化特性［２,３］以及好的非磁特性［４,５］,人们对这种合金的沉积方法进行了大量的研究．磷是一种不能从水溶液中单独进行电沉积的元素 ,但它很容易和铁组元素共沉积．为了解释这一现象 ,Ｂｒｅｎｎｅｒ曾提出直接机理［６］．认为镀液中磷的含氧酸 (根 )直接在电极上还原成合金中的磷．然而 ,磷不能用电化学方法以纯态沉积出来,所以直接机理没有被广泛接受．第二种是由Ｆｅｄｏｔ′ｅｖ等提出的间接机理［７］,认为磷的含氧酸（根）首先还原成磷化氢（ＰＨ…     

溶液法铝诱导晶化多晶硅薄膜

介绍了一种基于溶液的廉价制备Al诱导晶化多晶硅薄膜的方法. 先以低压化学气相沉积(LPCVD)方法制备50 nm厚的非晶硅(amorphous silicon, a-Si)薄膜作为前驱物, 通过旋涂的方法, 将含有Al的盐溶液涂覆在a-Si薄膜表面, 550-620 ℃下氮气氛围退火若干小时得到多晶硅薄膜. 文中针对化学诱导源的种类、前驱物表面状况对晶化效果的影响进行了研究. 发现只有反应生成物中含有偏铝酸根(AlO-2)的碱性溶液才能发生诱导晶化, 而若Al溶液浓度过低, 则不能得到连续的多晶硅薄膜. a-Si表面若附有薄氧化层会有利于Al盐溶液在表面上的粘附以及得到大尺寸的晶粒, 然而又会增高退火晶化所需要的温度. 同时溶液在薄膜表面的粘附状况还会受到溶液中存在的其它离子的影响. 因此必须选用合适的实验条件.     

Direct imaging of smectic B phase of poly(p-xylylene)

Single crystals of poly(p-xylylene) were grown in dilute α-methylnaphthalene solution and studied by bright-field and high-resolution electron microscopy (HREM). The crystallization process was discussed in terms of the dependence of crystal form on crystallization conditions. A 0.15 nm resolution was achieved from high-resolution images of a frozen liquid crystalline phase. High-temperature electron diffraction patterns confirmed the existence of the liquid-crystalline phase in agreement with previous work of Lieser. The HREM images show the molecular packing in the smectic B phase. © 1992 John Wiley & Sons, Inc.     

Single crystal morphology and structural data of a series of polyesters derived from 1,8-octanediol

The morphology of solution grown single crystals of a series of polyesters derived from 1,8-octanediol and either an even or an odd dicarboxylic acid has been investigated. Different crystallization conditions (solvent and temperature) were tested for these polyesters whose dicarboxylate unit varied from pimelate to sebacate. Crystals showed a lozenge morphology with a degree of truncation which for a given solvent changed with the crystallization temperature. Curvature of growth faces, striations on the lamellar surface and a bilayered morphology were features that were observed in some cases. Polyethylene decoration highlighted a crystal sectorization and suggested a molecular folding parallel to the crystal growth faces.The studied polyesters always showed a single crystalline structure, according to electron and X-ray diffraction data. A practically all trans molecular conformation could always be deduced. Unit cell geometry changed from orthorhombic to monoclinic and the molecular content was variable in the studied series (two or four molecular segments).Lamellae gave rise to well-defined electron diffraction patterns that allowed the setting angle of molecular segments to be determined. A good agreement between simulated and experimental hk0 diffraction patterns was always found. Packing along the chain axis direction was completely defined for the sebacate derivative.     

Dissipative crystallization of potassium salt of poly(riboadenylic acid)

Dissipative patterns during the course of dryness of aqueous solution of potassium salt of poly(riboadenylic acid) (KPolyA) in the presence of potassium chloride were studied on a cover glass, a watch glass and a glass dish. Accumulation of KPolyA polymers forming the broad ring area and the drastic change in size and shape of the polymer single crystals depending on the location of the dried film, which are the typical effects of the dissipative crystallization, took place. Polymer crystals formed were spherulites, dendritic and rod-like assemblies, which are composed of the single or double helical chains depending on the pH-value of the initial solution.     

Increasing Crystallization Rate in Growing Single Crystals of Quartz

A new method was proposed to increase the crystallization rate in growing single crystals of quartz. In this method, the crystallization is accelerated by using surfactants (polyethyleneamine, tetramethylammonium base, and polyethyleneimine) added to a soda-alkaline solution of standard concentration. Within studied ranges of pressures and concentrations of components of the solution, polyethyleneimine at a concentration of 0.002–0.05 wt % is the most efficient crystallization accelerator, which can increase the quartz crystal growth rate on the average by a factor of 2.     

Solution crystallization analysis of poly(lactic acid) by Scalls: A facile approach for thermal analysis of polymers in solution

Non-isothermal solution crystallization and dissolution behaviour of both enantiomers (D and L) of poly(lactic acid) (PLA) and their blends were studied by the unique Solution Crystallization Analysis by Laser Light Scattering (Scalls) method. For the first time, we have investigated the crystallization of this biopolymer in solution, as well as the subsequent dissolution or “solution melting”. It was found that addition of the D-enantiomer (PDLA) to the L-enantiomer (PLLA) in solution resulted in the formation of stereocomplex crystals (SC), and the nucleation-effect of the crystals was intensified with increase in PDLA content, leading to an earlier onset of crystallization and increased crystallization peak area. Differential Scanning Calorimetry (DSC) analysis confirmed the formation of SC during solution crystallization. Large re-crystallization events were seen for the pristine polymers, indicative of their low crystallization rates. Overall, results obtained by Scalls provided promising information regarding PLA crystallization kinetics, which significantly influences practical applications of this biopolymer.     

The influence of minor components on the structural reorganization in glassforming materials

Correlation of structure parameters of glasses and related crystals formed in homogeneous or heterogeneous nucleation processes by thermal treatment is discussed on the basis of DTA, TG and EGA measurements in relation to the textural patterns of the materials. For cordierite glass, crystallization of metastable disordered cordierite polymorphs is related to an exothermic heat evolution and simultaneous with a small weight loss (appr. 0.025%). By MS-EGA, evolution of water was determined during the transformation of the metastable melt to a metastable intermediate crystalline phase. Interpretation of the crystallization by comparing the available structure parameters of cordierite glasses and crystals alone is insufficient to explain the role of water in the kinetics of crystallization. Optical and electron microscopy of the primary crystallization phenomena show the metastable solid solution with low quartz-type structure. Interpretation of the crystallization behaviour in terms of conventional theory of nucleation and crystal growth is impossible.     

Computational study of solvent effects on the molecular self-assembly of tetrolic acid in solution and implications for the polymorph formed from crystallization

The solution behavior of a model compound, tetrolic acid (TTA), is studied via molecular dynamics simulations in four organic solvents. The results suggest that strong interactions between TTA and solvent molecules (ethanol or dioxane) prevent the formation of carboxylic acid dimers in solution and thus promote the crystallization of TTA in a catemer-based form or a solvate form. Weak interactions, however, between TTA and solvent molecules (carbon tetrachloride or chloroform) facilitate the formation of carboxylic acid dimers in solution and thus promote the crystallization of a dimer-based crystal. Detailed solvent structure plays an important role in determining the relative stability of various growth synthons in solution and also the barriers along the pathway connecting them. This work illustrates the potential of molecular simulations to aid in the rational selection of solvents to obtain desired polymorphs during crystallization.     

盐卤硼酸盐化学XIII;2MgO.2B2O3. Mgcl2.14H2O结晶动力学研究

本发明对MgO-B2O-MgCl2-H2O浓盐溶液结晶析出氯柱硼镁石(αMgO,αB2O3MgCl.14H2O)的动力学过程进行了研究, 利用单纯形优化法配合Runge-Kutta微分方程组数值解法对实验数据进行处理, 给出了结晶动力学方程, 并对硼在溶液中的存在形式进行了讨论, 提出了结晶反应机理, 同时考察了温度和氯化镁浓度对结晶速率的影响。     

Crystallization kinetics of poly(ethylene oxide) confined in semicrystalline poly(vinylidene) fluoride

Polymer blends based on poly(vinylidene fluoride) (PVDF) and poly(ethylene oxide) (PEO) have been prepared to analyze the crystallization kinetics of poly(ethylene oxide) confined in semicrystalline PVDF with different ratios of both polymers. Both blend components were dissolved in a common solvent, dimethyl formamide. Blend films were obtained by casting from the solution at 70 °C. Thus, PVDF crystals are formed by crystallization from the solution while PEO (which is in the liquid state during the whole process) is confined between PVDF crystallites. The kinetics of crystallization of the confined PEO phase was studied by isothermal and nonisothermal experiments. Fitting of Avrami model to the experimental DSC traces allows a quantitative comparison of the influence of the PVDF/PEO ratio in the blend on the crystallization behavior. The effect of melting and further recrystallization of the PVDF matrix on PEO confinement is also studied. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 588–597