胶晶/嵌段共聚物双重模板制备多级孔材料

采用分段乳液聚合法和无皂乳液聚合法制备了聚苯乙烯(PS)微球,以此单分散胶态晶体和嵌段共聚物P123为模板剂,通过Y型分子筛前驱体的填充和模板剂的去除制备了具有大-介-微多级孔的材料.采用XRD、SEM和TEM等手段表征了PS微球及多级孔材料.结果表明,分段乳液聚合可以制备平均粒径为50nm的PS微球,无皂乳液聚合可以制备450nm左右的PS微球;以其作为大孔模板剂分别考察了PS微球粒径、模板剂用量、水用量等因素对多级孔材料合成的影响,结果表明,PS微球的粒径越大,材料中大孔的分散性越好.合成多级孔材料的条件为:PS微球乳液与前驱体的比值(质量比)为1.0~0.5,水与前驱体的比值为7.5,P123与前驱体的比值为0.1.     

单分散聚苯乙烯微球合成及在三维有序大孔材料制备中的模板作用

通过乳液聚合得到了单分散的聚苯乙烯(PS)微球乳液并通过阳离子破乳沉降法实现PS微球自组装,得到了紧密堆积的PS微球的胶体模板剂。向PS胶体模板的空隙填充硅溶胶,再通过焙烧去除模板得到三维有序大孔(3DOM)二氧化硅(SiO_2)材料。采用扫描电子显微镜、透射电子显微镜、红外和热重分析等对合成的3D大孔SiO_2材料进行表征。结果表明:使用粒径不同的PS微球作为模板,制得的3D大孔SiO_2材料的孔径在200~400nm之间。该制备方法为多孔材料的制备开拓了一条可行、便捷的途径。     

水热法合成铬掺杂尖晶石型锂离子筛及其锂吸附性能

以LiOH、H2O2、Mn(NO3)2和Cr(NO3)3·9H2O为原料,直接水热合成出具有尖晶石结构的铬元素掺杂锂离子筛前驱体,再经酸浸脱锂后得到对Li+具有选择吸附性能的掺杂型锂离子筛;采用XRD和1R研究了产物的性能,测定了离子筛在不同pH值的纯锂溶液中对锂的饱和交换容量.结果表明,在LiOH浓度为1.1mol/...     

溶胶-凝胶模板法制备有序大孔TiO_2微球

以无皂乳液聚合方法自制的单分散聚苯乙烯(PS)微球乳液为原料,利用PS自组装制备了有序胶体晶体模板("蛋白石"),采用溶胶-凝胶模板法制备了有序大孔TiO2微球("反蛋白石"),其孔呈六边形,孔径分布均一,约为200nm。运用扫描电镜(SEM)、X射线衍射(XRD)对其形貌特征及晶型进行了表征,结果表明,采用表面含有羧基的单分散聚苯乙烯微球及高的硅油黏度制得的模板有序度高;通过控制煅烧温度可以改变有序大孔TiO2微球的晶型,当煅烧温度为500℃时,其晶型为锐钛型,当煅烧温度为700℃时,其晶型则为金红石型。     

聚苯乙烯微球模板法制备反蛋白石型光子晶体水凝胶薄膜

用乳液聚合法制备了系列单分散且粒径均一的聚苯乙烯纳米微球,以正交试验优化反应中各物质的用量对聚苯乙烯纳米微球的粒径大小及分布的影响,实现了在150~350nm范围内PS纳米微球的可控制备。以不同粒径的PS纳米微球作为模板,以丙烯酰胺和丙烯酸作为原料制备了一系列反蛋白石型光子晶体水凝胶。通过比较它们之间的初始反射峰位置及反射峰变化范围,表明以300nm左右的PS纳米微球作为模板制备的水凝胶在可见光范围内有较大的变化范围,并且有较好的形貌。     

胶体晶体模板法制备有序多孔TiO_2薄膜的研究

采用两阶段种子乳液聚合法制备了表面含一定量HEA的单分散P(St-co-HEA)微球,通过垂直成膜法,在适当温度下制得该微球的胶体晶体薄膜,配置以钛酸四丁酯为钛源的前驱体溶液来浸泡该薄膜,充分水解后,煅烧除去该模板,即得到有序多孔的TiO_2薄膜.研究了聚合反应过程中,引发剂用量、反应温度、反应时间、第二单体量等对单体转化率、微球形貌及粒径的影响.采用FTIR、SEM等对单分散P(St-co-HEA.)微球粒径及形貌进行了表征.并对最终的TiO_2薄膜进行了SEM表征,其平均孔径约为190nm.     

粒径及壁厚可控的二氧化硅空心微球的研究(英文)

二氧化硅空心微球是由模板/溶胶?凝胶法制备的,其中模板选用的是阳离子型聚苯乙烯(PS),前驱体采用的是正硅酸乙酯(TEOS).二氧化硅空心微球的空腔大小由PS模板的尺寸决定,所以通过改变聚合反应的参数(单体、引发剂、稳定剂、分散介质的极性),可以制得粒径范围在0.71～1.80μm的二氧化硅空心微球.改变TEOS的浓度为0.4～0.8mmol/L,可以得到壁厚为20～60nm的二氧化硅空心微球.空心微球的粒径和壁厚将会影响粉体的堆积密度,而这同样会影响到以二氧化硅空心微球为原料制备的材料的热导率及强度.     

煅烧温度对TiO_2中空微球光催化性能的影响

以分散聚合法制得的单分散阳离子聚苯乙烯（PS）微球为模板,钛酸丁酯为前驱体,采用溶胶-凝胶法在模板表面包覆TiO2壳层,并在不同煅烧温度下制备了晶相结构不同的微米级中空TiO2微球。采用TEM、SEM、FT-IR、XRD、UV-Vis DRS对样品的微观结构、相态组成及光催化性能进行了表征。结果表明TiO2中空微球平均粒径达到1.23μm,壳层厚度约为30nm;随着煅烧温度增加,锐钛矿晶粒尺寸会增加,并在700℃时出现混晶结构;在500℃煅烧得到的TiO2中空微球对甲基橙（MO）降解表现出比P25更好的光催化性能及光催化稳定性。     

单分散中空聚苯乙烯微球制备

采用搅拌乳化方法制备水包油(W1/O)型乳状液,经膜乳化法制得单分散的复乳(W1/O/W2)型乳状液,再通过液中干燥法制得单分散中空聚苯乙烯(PS)微球.考察了shirasu porous glass(SPG)膜孔径对乳状液液滴粒径及粒径分布、表面活性剂浓度对PS微球中空率和单分散性的影响.由激光粒度分析仪结果及PS微球的SEM照片证实,制得的PS微球,粒径呈单分散,是SPG膜孔径的2.0～2.4倍且具有中空结构.     

单分散聚苯乙烯微球的制备及二维胶体晶体的自组装

以苯乙烯为原料、过硫酸钾为引发剂,采用无皂乳液聚合法成功地制备出具有良好球形度的单分散聚苯乙烯微球.研究了在聚苯乙烯微球合成过程中单体浓度、引发剂浓度、聚合时间对粒径及分布的影响.实验结果表明,适当改变单体浓度、引发剂浓度、聚合时间可以得到不同粒径的聚苯乙烯微球,且微球单分散性良好.采用自组装技术组装单分散聚苯乙烯微球,获得了二维有序聚苯乙烯胶体晶体.     

热交换器的分类及优缺点分析

热交换器是将不同温度介质之间的热量通过热传导的形式,由高温介质传递给低温介质,使介质达到生产所需温度的工艺设备,也可作为一种节能设备使用.通过对不同热交换器的结构分析,总结不同热交换器的优缺点、适用环境,为生产工艺设计人员及设备制造单位在选择可降低能耗、提高效率的设备上提供参考.     

聚苯胺及其复合物的制备和结构及形貌分析

通过化学氧化法分别制备盐酸,盐酸和十二烷基苯磺酸,碳纳米管(MWNTs-COOH)掺杂的聚苯胺,利用红外光谱,紫外光谱,扫描电子显微镜和透射电子显微镜对所制备聚苯胺的结构和形貌进行分析。分析不同掺杂物对聚苯胺的结构和形貌的影响;同时研究了超声波作用对聚苯胺形貌以及聚苯胺包裹MWNTs-COOH情况的影响。     

Modelling and computation of curing and damage of thermosets

The curing of thermosets is a complex process involving the transition from a fluid into a (visco-) elastic solid. This phase transition comes along with an increase in stiffness and a volume shrinkage of the polymer. The latter may lead to severe residual strains and stresses, which in turn can cause damage in the final, usually quasi-brittle material. In this contribution a constitutive model is developed which takes into account the curing of a thermosetting material together with the process-induced damage as resulting from curing shrinkage. The curing of the material is governed by a phenomenological hypoelastic constitutive equation which includes temporal evolutions for stiffness and volume shrinkage. Thermal and viscous effects are neglected in the present study. An isotropic gradient-enhanced damage model is adapted to describe the damage evolution. The curing-damage model is implemented into a finite element code and numerical examples for thermosetting materials demonstrate that the proposed model is capable to predict cure-induced damage in thermosets.     

Thermodynamic similarity and prediction of the properties and characteristics of substances and processes

Principles of the theory of thermodynamic similarity are considered in application to all aggregate states of a substance, including phase transitions, and to the change in dissipative structures in open systems.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 5, pp. 709–716, November, 1987.     

Mechanisms of Corosion and Oxidation of Metals and Alloys

Selected topics in field of the study of the mechanisms of corrosion and of oxidation of metals or alloys are presented. The first part reports a new model for the mechanism of the breakaway oxidation of ferritic stainless steels in water vapour. The second part is devoted to the physico‐chemical aspects of oxidation and presents experimental methods useful in the kinetic modelling applied to two alloys, the zircalloy‐4 and an AlMg5 % in the liquid state. In the third part the physical and numerical modelling of the stress corrosion cracking behaviour in face‐centered cubic (fcc) alloys is detailed, which enables the study of the influence of macroscopic parameters (such as the temperature or hydrogen activity) on the fracture process.     

碳化硼陶瓷增韧补强和致密化研究现状及其展望

碳化硼陶瓷具有极高的硬度,然而其低韧性、低抗弯强度、难以致密化限制了它的广泛应用.已有一些研究集中于碳化硼陶瓷增韧补强和致密化,对这一方面国内外研究进展进行了归纳与评述,阐明各种增韧补强和致密化方法的优缺点,提出碳化硼陶瓷增韧补强和致密化研究值得发展的一些方向.     

Measurement and analysis of elastic and anelastic properties of alumina and silicon carbide

Measurements of dynamic Young's modulus, E, and damping as a function of temperature, T, were made for alumina and silicon carbide. The Young's modulus data were compared with some from the literature, and analysed in terms of a theoretical framework relating the Debye temperature, θD, with the elastic constants. For both materials this analysis yielded a ratio T₀/θ_D which was near 0.4, where T₀ is an empirical fitting constant for the plot of (E(0)−E)/T versus 1/T (E(0) is the value of E at 0 K). The analysis of the damping data in terms of an Arrhenius type dependence led to effective activation energies near kT, where k is Boltzmann's constant. This revised version was published online in November 2006 with corrections to the Cover Date.     

Preparation and characterization of phosphate and arsenate apatites of strontium and their solid solutions

Samples of phosphate and arsenate apatites of strontium and six of their solid solutions, spread over the entire compositional range, were prepared by a wet method. They were characterized by chemical, X-ray, electron microscopic and infrared analyses. The validity of Vegard's law established the homogeneity of the solid solutions.     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。