甲酰胺对有序介孔二氧化硅形貌的影响

At room temperature and in acidic solution, ordered mesoporous silicas with particular morphology were synthesized using cetylpyridinium chloride as the template and formamide as the cosolvent. Scanning electron microscope (SEM), small angle X-ray diffraction (SXRD), and nitrogen adsorption techniques were used to characterize the as-synthesized and calcined samples. Results showed that the samples had hexagonal mesostructure analogous to MCM-41 and relatively narrow pore-size distributions (BJH). Besides, BET surface areas of the samples were in the range of 1 000～1 250 m²·g^-1 and high total pore volumes were up to 1.367 cm³·g^-1. Addition of formamide affected obviously mesostructures and the morphology of the mesoporous silica. Furthermore, with the increase of the concentration of formamide, the unit-cell constant decreased and particle shape changed from gyroids to fibers.     

聚丙烯/POE共混组成对材料断裂行为的影响

采用基本断裂功(EWF)方法对聚丙烯(PP)/聚烯烃弹性体(POE)共混物的注射双边缺口拉伸试样的断裂行为进行了研究,比较了不同POE含量对共混物各断裂参数的影响.结果表明,PP和用量为5phr POE的共混物都可完全满足EWF方法的要求,共混物的断裂韧性-比基本断裂功we,较PP有显著提高;POE用量为10phr以上的共混物则出现明显的成颈现象而限制了EWF方法的应用;PP和各种POE用量的共混物都得到了其屈服所需要的比基本断裂功we,y和比塑性功β′wp,y.     

Fabrication of hexaphenylsilole nanowires and their morphology-tunable photoluminescence.

Immersion of nanoporous alumina membranes into saturated solutions of hexaphenylsilole with subsequent solvent evaporation affords aligned organic nanowires. The luminescent properties of the hexaphenylsilole nanowires can be manipulated by varying their morphologies, which were controlled by changing the channel sizes of the alumina templates.     

Conductive polyethylene-carbon black composites by elongational-flow injection molding Part 3. Study of the structure and morphology

The morphology and structure of high molecular weight linear polyethylene (M _w 450000) filled with carbon black and processed using molds that introduce an elongational flow component during injection molding has been examined using electron microscopy and x-ray diffraction techniques. The study of fracture surfaces reveals the display of shish-kebabs oriented along the injection direction with segregated longitudinal channels of carbon black particles. Molecular and lamellar changes in orientation are, furthermore, studied across the thickness of the moldings. It is shown that addition of carbon black particles to injection-molded polyethylene induces significant changes in lamellar orientation. Thus, while lamellar overgrowth proceeds perpendicular to the fiber axes within carbon free channels, lamellae grow randomly within carbon-enriched regions where flow is less pronounced.     

INFLUENCES OF ACID POST-TREATMENT ON THE MORPHOLOGY OF SOAPFREE P（MMA-EA-MAA） PARTICLES PREPARED BY SEEDED EMULSION POLYMERIZATION

Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.     

老年髋部骨折患者血清中宏量及微量元素含量分析

为探讨微量元素与骨质疏松症及髋部骨折的关系,采用原子吸收分光光度计等方法分别测定了40例老年髋部骨折患者血清中微量元素铜(Cu)、锌(Zn)、硒(Se)、铁(Fe)、锰(Mn)及宏量元素钙(Ca)、磷(P)、镁(Mg)、钾(K)、钠(Na)的含量,并与30例青壮年髋部骨折患者对照。结果表明,老年髋部骨折患者血清中的Ca含量明显升高(P<0.01)、Cu、Mn有显著提高(P<0.05),其它元素有升高趋势,但无显著性差异,Zn的含量明显降低(P<0.01)。测定血清中宏量及微量元素含量可能对预测髋部骨折及骨质疏松症的疗效评价有一定临床价值。     

CdSe纳米线阵列的制备及其表征(英)

通过在含有SeSO₃^2-和Cd²⁺的室温水溶液中，用模板-电沉积法在纳米孔阵列阳极氧化铝膜(AAM)模板中制备了高有序性的CdSe纳米线阵列，并对其形貌、结构和组分进行了表征。扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果表明，纳米线阵列中的CdSe纳米线具有相同的长度和直径，分别对应于使用的AAM模板的厚度和孔径；X-射线衍射(XRD)和X-射线能谱(EDAX)结果表明，CdSe纳米线中Cd和Se的化学组成非常接近于1∶1，其结构为立方CdSe。另外，对模板-电沉积法制备CdSe纳米线的机理进行了讨论。     

ATOMIC FORCE MICROSCOPY STUDIES OF POLYCAPROLACTONE RINGED SPHERULITES*

The surface morphology of free-surface PCL ringed spherulites was investigated by using atomic forcemicroscopy. The spherulites were obtained by crystallization of PCL/PVC blends of different compositions. It was found thatthe ringed spherulite exhibited regularly fluctuating rings on its surface. Compared with the bright-dark ring pattern of thespherulite under a polarizing microscope, it was proved that the optical characteristics of the ringed spherulite underpolarizing microscope coincided with its surface characteristics. The bright rings in polarizing micrographs of the spherulite coincided with the convex rings on its surface, while the dark rings coincided with the concave rings.     

Morphology control of soap-free seeded P(St-EA-AA) latex particles

Soap-free poly(styrene-ethyl acrylate-acrylic acid) latex particles with narrow size distribution and with surface carboxyl groups were synthesized by semicontinuous emulsion polymerization, and the particles with homogeneous multihollow structure were obtained after alkali posttreatment. Effects of treatment conditions and crosslinking agents on particle morphology were investigated. Results showed that the multihollow structure can be formed inside the uncrosslinked particles only when the treatment temperature exceeded 50 °C, the pH was higher than 10.0, the amount of 2-butanone was more than 3.0 ml and the treatment time was longer than 30 min. Furthermore, the volume expansion of the particles increased with the temperature increased to 90 °C, the pH to 12.5 or the amount of 2-butanone to 7.0 ml, and this value increased first and then decreased with the treatment time prolonged. Fine pores can be generated in the shell of particles crosslinked by 0.2 g of ethyl glycol dimethylacrylate (EGDMA), while no hollow structure formed inside particles when 0.4 g of EGDMA or 0.2 g of divinyl benzene was used.     

Thermal Analysis of Acrylonitrile Polymerization and Cyclization in the Presence of N,N-Dimethylformamide

This paper examines the polymerization of acrylonitrile to poly(acrylonitrile)(PAN), and its cyclization, in bulk form and using N,N-dimethylformamide (DMF) as solvent in which both monomer and polymer are soluble. Thermal analysis of the resultant products after polymerization has been performed by DSC and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Scanning electron microscopy has been used to study the morphology of the resultant products and after thermal treatments. The DSC thermal curve of PAN-DMF sample is quite different from the PAN bulk sample, showing a single sharp exothermic peak associated with nitrile group polymerization (cyclization) of PAN at lower temperature (240°C) than that of bulk PAN sample (314°C). Cyclization of PAN was confirmed by IR spectroscopy. It was found that the amide molecules are difficult to eliminate completely in the product obtained after the polymerization reaction, even after prolonged heating at 110°C, and remain occluded. The formation of a complex by dipolar bonding is also possible and it is discussed. It is concluded that the amount of heat evolved as well as the temperature interval over which it is released are influenced by the chemical processing of PAN when using DMF as solvent of both monomer and polymer. Pyrolysis of these PAN samples revealed the release of occluded molecules of DMF, and several compounds containing nitrogen produced from the thermal degradation processes. All these results are interesting to know the chemical processing of carbon fibres and activated carbon fibres from PAN modified precursors.This revised version was published online in November 2005 with corrections to the Cover Date.