热处理对聚乙烯／炭黑导电复合体系形态结构及PTC特性的影响

借助ＷＡＸＤ、ＳＡＸＤ和ＤＳＣ等手段研究了炭黑与聚乙烯复合体系在不同热处理条件下的结晶行为及聚集态结构的大尺寸效应对ＰＴＣ特性的影响。由此提出，不仅结晶度大小，而且聚集大尺寸效应性能对ＰＴＣ行性有重要影响的新观点。     

Preparation of block copolymer vesicles in solution

Block copolymer vesicles can be prepared in solution from a variety of different amphiphilic systems. Polystyrene‐block‐poly(acrylic acid), polystyrene‐block‐poly(ethylene oxide), and many other block copolymer systems can produce vesicles of a wide range of sizes; those in the range of 100–1000 nm have been explored extensively. Different factors, such as the absolute and relative block lengths, the presence of additives (ions, homopolymers, and surfactants), the water content in the solvent mixture, the nature and composition of the solvent, the temperature, and the polydispersity of the hydrophilic block, provide control over the types of vesicles produced. Their high stability, resistance to many external stimuli, and ability to package both hydrophilic and hydrophobic compounds make them excellent candidates for use in the medical, pharmaceutical, and environmental fields. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 923–938, 2004     

Morphology Control over the Organic Nanoparticles of 1,3-Diphenyl-5-（9-anthryl）-2-pyrazoline

The organic nanoparticles of a blue-light-emitting molecule, 1,3-diphenyl-5-(9-anthryl)-2-pyrazuline, were prepared by reprecipitation method using acetonitrile as the solvent for the molecular precursor. Three morphologies, spherical, doughnut-shaped and cubic, could be observed on the silicon substrate forthe nanoparfides by the volume-controlled addition of acetonitrile. The evolution of particle morphology as a function of acetonitrile addition was attributed to the variation of the growth habits of the particles in the different environment. The nanoparticles exhibit the novel photoluminescence spectra as compared to those of monomer and the bulk crystals.     

MAA存在下VAc/BA核壳乳液聚合过程中的胶粒形态研究

用ＴＥＭ和电位滴定法对不同配方和工艺条件得到的胶粒形态结构和羧基分别进行了表征。结果表明：加入甲基丙烯酸有利于胶粒的稳定和形成规则的核壳胶粒。半连续加料不会形成完全反转的核壳结构,但是,核层在反应过程中由于聚合物簇的迁移会造成形变。由于胶粒中聚合物浓度高,粘度大,因而胶粒形态变化受动力学影响甚大,羧基分布主要是由动力学确定的。     

气相法分析3-氯-2-羟丙基三甲基氯化铵中的微量有机杂质

 以氯仿为萃取剂 ,对 3 氯 2 羟丙基三甲基氯化铵 (CHPTMA)水溶液进行萃取 ,用气相法分析了CHPT MA溶液中的微量有机杂质环氧氯丙烷和 1 3 二氯丙醇。柱为 2m× 3mmi d 的不锈钢填充柱 ,固定相为10 %的PEG 2 0M ,载体为ChromosorbW/AW。环氧氯丙烷和 1,3 二氯丙醇的回收率分别为 97 5 %～ 10 5 0 %和93 3%～ 98 8% ,相对标准偏差分别为 11 5 %和 13 1% ,最低检测限分别为 5 0 μg/g和 10 0 μg/ g。     

聚己内酯/硝基纤维素共混体系结晶行为的研究

通过对聚己内酯／硝基纤维素共混体系的热分析、傅立叶变换红外光谱的研究，证实了该共混体系在聚己内酯含量较高时，是一个热力学相容的体系，同时两组分之间存在强的氢键相互作用。在此体系中聚己内酯长成了清晰规整的环带球晶。聚己内酯结晶形态随结晶温度和共混物组成的变化表明，在共混体系中聚己内酯结晶速率与非晶第二组分的扩散速率存在一定的匹配关系，是影响环带球晶形成的重要因素。     

A New Kind of Void Soap-free P（MMA-EA-MAA） Latex Particles

Soap-flee P(MMA-EA-MAA) particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and methacrylic acid (MAA), and large voids inside the particles were generated by alkali posttreatment in the presence of 2-butanone. Results indicated that the size of void and theparticle volume were related with the amount of 2-butanone. The generation mechanism of voids was proposed.     

Fluoroapatite - material for medicine,Growth, morphology and thermoanalytical properties

Fluoroapatite containing glass-ceramics were prepared from Li₂O-CaO-CaF₂-P₂O₅-SiO₂ system. The glass was melted at 1480°C for 1 h. The object of observation was the preparing crystal phase of fluoroapatite in amorphous glass matrix. The morphology of lithium disilicate glass-ceramics was studied by SEM. The crystal growth and thermal properties of fluoroapatite were studied by X-ray diffraction and DTA. The more the content of P₂O₅, the more the presence of fluoroapatite particles. SEM investigation clearly indicated the phase separation and formation of a primary crystalline phase of fluoroapatite in the studied glass-ceramics. DTA curves of the fluoroapatite samples exhibit exothermic effects in the temperature range 337-694°C depending on the composition of the materials. The position of exothermic peak for lithium disilicate on DTA curves moves with increasing specific surfacetowards lower temperatures which points on its preferential surface crystallization. As far as physical qualities are concerned, mainly color and gloss, the best qualities of all observed materials belong to glass-ceramics with 10% P₂O₅. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Sialons MLn[Si4−xAlxOxN7−x] with M = Eu,Sr, Ba and Ln = Ho‐Yb – Twelve Substitution Variants with the MYb[Si4N7] Structure Type

The oxonitridoalumosilicates (so‐called sialons) MLn[Si_4?xAl_xO_xN_7?x] with M = Eu, Sr, Ba and Ln =Ho, Er, Tm, Yb were obtained by the reaction of the respective lanthanoid metal, the alkaline earth carbonates or europium carbonate, resp., AlN, “Si(NH)₂” and MCl₂ as a flux in a radiofrequency furnace at temperatures around 2100 °C. The compounds MLn[Si_4?xAl_xO_xN_7?x] are relevant for the investigation of substitutional effects on the materials properties due to their ability of tolerating a comparatively large phase width up to x ≈ 2.0(5). The crystal structures of the twelve compounds were refined from X‐ray single crystal data and X‐ray powder data and are found to be isotypic to the MYb[Si₄N₇] structure type. The compounds crystallize in space group P6₃mc (no. 186, hexagonal) and are made up of chains of so‐called starlike units [N^[4](SiN₃)₄] or [N^[4]((Si,Al)(O,N)₃)₄], respectively. These units are formed by four (Si,Al)(N/O)₄ tetrahedra sharing a common central nitrogen atom. The structure refinement was performed utilizing an O/N‐distribution model according to Paulings rules, i.e. nitrogen was positioned on the four‐fold bridging site and nitrogen and oxygen were distributed equally on both of the two‐fold bridging sites, resulting in charge neutrality of the compound. The Si and Al atoms were distributed equally on their two crystallographic sites, referring to their elemental proportion in the compound, due to being poorly distinguishable by X‐ray methods. The chemical compositions of the compounds were derived from electron probe micro analyses (EPMA).     

Cure kinetics of epoxy resin and thermoplastic polymer

The cure kinetics and morphology of diglycidyl ether of bisphenol A (DGEBA) modified with polyvinyl acetate (PVAc) using diaminodiphenylmethane (DDM) as hardener were investigated through differential scanning calorimetry (DSC) and environmental scanning electron microscopy (ESEM). Isothermal curing measurements were carried out at 150, 120 and 80°C. The kinetic parameters were obtained using the general autocatalytic chemically controlled model. The comparison of the kinetic data indicates that the presence of PVAc does not change the autocatalytic nature of the cure reaction. Two T _g’s were observed in the fully cured samples of the modified systems. ESEM micrographies confirm the biphasic morphology.