静态混合器对PP/MMT纳米复合材料微观形态的影响

以聚丙烯／蒙脱土纳米复合材料(PP／MMT)为原料，在单螺杆挤出装置上，通过连接Kenics静态混合器，研究了静态混合器对PP／MMT微观形态的影响，并用透射电子显微镜(TEM)研究了MMT在PP中分散的形态。结果表明：通过Kenics静态混合器混合后，MMT在基体PP中的分散更加均匀，并出现明显的片层剥离；混沌混合是获取剥离型PP／MMT的有效手段。     

丙烯酸乙酯合成反应产物的GC／MS分析

本文叙述了丙烯酸乙酯合成产物的ＧＣ／ＭＳ分析．从分析结果看出，本应在酯化反应前除去的ＣＨ３Ｃｌ３仍有较大的含量，这也许是导致丙烯酸乙酯被氯代的原因。     

一种户外多功能定位与测量装置的设计实现

本设计是针对在户外登山、旅行、勘测过程中常常既需要定位系统,又需要温度、高度、气压、湿度等参数测量系统的情况下,设计的一种多功能便携式测量工具。本系统采用STM32作为控制器,移植了μC/OS实时操作系统,驱动GPS模块和各种传感器模块,实现了数据的实时采集显示。本系统采用了0.96’OLED作为显示单元,STM32引入了低功耗模式,锂电池供电,提升了系统的便携性和低功耗。     

Effect of Ti–Si–Fe alloys on microstructure and properties of nitride/oxynitride bonded SiC ceramics sintered under CO/N2 atmosphere

Ti–Si–Fe alloys extracted from high-titanium blast furnace slag were utilized to replace part of the silicon powders, and then nitride/oxynitride bonded SiC ceramics were prepared by reactive sintering in graphite bed. Ti–Si–Fe alloys could react with CO/N₂ at a low temperature (1200 °C), and the addition of Ti–Si–Fe alloys could reduce the nitriding temperature of Si. Density functional theory calculations suggested that Ti–Si–Fe alloys enhanced reaction activity via weakening the strength of CO and NN bonds. The regional equilibrium phase diagrams of Si–C–N–O and Ti–Si–C–N–O under CO/N₂ atmosphere were calculated by thermodynamics. The change of whiskers morphology was observed by scanning electron microscope. Furthermore, the bulk density, the cold modulus of rupture, and the cold compressive strength improved with Ti–Si–Fe alloys content. The results showed that the addition of Ti–Si–Fe alloys not only significantly promoted nitriding of Si and formation of Si₃N₄ whiskers, but also improved the mechanical properties of the samples.     

MnFe/H-ZSM-5混合催化剂上CO加氢合成芳烃

合成了H-ZSM-5型分子筛,并用连续沉淀法制备了FT合成催化剂MnFe。对混合催化剂MnFe/H-ZSM-5上CO加氢合成芳烃的催化行为作了研究。并考察了分子筛组分、粒度、反应工艺条件对反应速度及芳烃收率的影响。试验结果表明,粒度在20μm-25μm范围内的反应已排除内扩散控制的影响,芳烃收率可达40％,烃类产物分子量的分布不再服从Schulz-Flory分子量分布规律。     

Complex formation in a ternary system composed of lauroamphoglycinate, oleic acid, and water

The formation of a complex, composed of lauroamphoglycinate (LG), oleic acid (OA) and water, was investigated, and this system was applied to emulsification. The complex was formed in the water-rich area (more than 90% in this system) at a molar ratio of OA to LG from 1 to 3, where two-phase systems of water and the complex existed. The interaction between LG and OA, both in the aqueous solution and at the interface of liquid paraffin dissolving the OA and LG solution, was studied by pH measurements and interfacial tension measurements, respectively. The results implied that LG and OA were linked stoichiometrically, both in aqueous solution and at the interface, and formed complexes. X-ray diffraction patterns and the strong hydrophobicity showed that the equimolar complex composed of LG, OA, and water was a liquid crystal with a reversed hexagonal structure. The reversed hexagonal liquid crystal was capable of solubilizing a certain amount of liquid paraffin in its alkyl group parts while maintaining its hexagonal structure. These results suggest the possibility to prepare a W/O-type emulsion by using the liquid crystal formed by LG, OA, partial liquid paraffin, and water as the continuous phase. The authors could obtain a stable W/O emulsion without coalescence of the water droplets that contained a substantial amount of water (approximately 90%). Furthermore, various types of emulsions, O/W, W/O, W/O/W, could be prepared by changing the ratio of LG and OA.     

Single‐pack,self‐curable,aqueous‐based polyurethane dispersion containing a disperse dye

An organic‐solvent‐soluble disperse dye was introduced into an aqueous phase by a reaction with a self‐emulsified, aqueous‐based polyurethane (PU), and this resulted in the formation of a homogeneous, aqueous polymeric dye dispersion. This aqueous polymeric dye was stable in a water phase with excellent color extension upon application. It was formulated with a latent curing agent, polyaziridine (e.g., TMPTA‐AZ), as a single‐component, self‐curable, aqueous polymeric dye. The curing reaction took place between PU carboxylic acid and the latent curing agent upon drying. A self‐cured polymeric dye was obtained with excellent color extension and fastness and resistance to organic solvents and water after drying. This single‐component, self‐curable, aqueous‐based PU system containing a dye has potential for printing, writing, and dyeing applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2006 © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3741–3747, 2006     

Supramolecular complexes: lamellar structure and crystalline transformation

Interfacial reaction of highly-branched polyethyleneimine (PEI) with octadecanoic acid (OA) was performed to prepare a series of supramolecular complexes (PEI(OA)_x). The complexes at solid state have typical lamellar structure, and the interlamellar distance can be modulated by the OA content. The long period values of the supramolecular complexes measured by SAXS were found to be dependent on the compositions, which are in good consistency with those measured by TEM. For example, the long period values from SAXS for PEI(OA)_0.76, PEI(OA)_1.03, and PEI(OA)_1.67 were 46.5, 62.7, and 56.2 Å, respectively. The corresponding data from TEM were 45.7, 60.7, and 56.6 Å, respectively. A model was proposed for the construction mode of the side alkyl chains (crystallization region) associated with PEI backbone (amorphous region), in which the side alkyl chains were arranged to be ‘end-to-end’ packing for the x=1 complex, while an ‘interdigitated structure’ of the side alkyl chains was deduced for the x>1 and x<1 complexes. Temperature variable FT-IR combination investigation of the scissoring band, rocking band, and stretching band of methylene (CH₂) and vibrational band of carbonyl group (CO) indicated that the crystalline form of the crystallization region in the lamellae can be transformed from orthorhombic to hexagonal with the temperature increasing, and vice versa.     

Microstructure of Pd/CeO2 catalyst: Effect of high temperature reduction in hydrogen

The effect of high temperature reduction (HTR) in hydrogen (up to 1180 K) on the microstructure of 9 wt.-% Pd/CeO₂ catalyst was studied by HRTEM and XRD methods. Reduction of the catalyst at or above 973 K caused severe recrystallization of CeO₂ and Pd with simultaneous strong interaction between the two components appearing as three phenomena: epitaxial growth of small Pd particles on CeO₂ (most frequently with [111]Pd[111]CeO₂); decoration of large Pd particles with ordered CeO₂ overlayer and expansion of the lattice parameter of Pd (by 2.1%). The origin of the Pd lattice expansion is discussed and diffusion of Ce species into the Pd lattice seems to be the most probable one. HTR caused also phase transformations in the ceria support. At 973 K and 1100 K, whole CeO₂ was transformed into oxygen deficient CeO_x phase exhibiting the same or similar structure but with expanded lattice parameter (by 2.8%). At 1180 K most ceria was transformed into hexagonal A-Ce₂₃. The CeO_x phase appeared to be stable in hydrogen and in vacuum at room temperature, but upon exposure to air at room temperature it rapidly reoxidised to CeO₂. Ce₂O₃ also reoxidised to CeO₂ but much slower. Another consequence of HTR at or above 773 K was formation of pits in CeO₂ crystallites, mainly on (112)-type crystal faces. The pits (1–10 nm) exhibited well defined walls parallel to CeO₂ lattice fringes and they could possibly constitute nucleation sites for strongly bonded, epitaxial oriented Pd particles.     

Morphology and mechanical properties of polypropylene/organoclay nanocomposites

Polypropylene (PP) nanocomposites were prepared by melt intercalation in an intermeshing corotating twin‐screw extruder. The effect of molecular weight of PP‐MA (maleic anhydride‐ modified polypropylene) on clay dispersion and mechanical properties of nanocomposites was investigated. After injection molding, the tensile properties and impact strength were measured. The best overall mechanical properties were found for composites containing PP‐MA having the highest molecular weight. The basal spacing of clay in the composites was measured by X‐ray diffraction (XRD). Nanoscale morphology of the samples was observed by transmission electron microscopy (TEM). The crystallization kinetics was measured by differential scanning calorimetry (DSC) and optical microscopy at a fixed crystallization temperature. Increasing the clay content in PP‐ MA330k/clay, a well‐dispersed two‐component system, caused the impact strength to decrease while the crystallization kinetics and the spherulite size remained almost the same. On the other hand, PP/PP‐MA330k/clay, an intercalated three‐component system containing some dispersed clay as well as the clay tactoids, showed a much smaller size of spherulites and a slight increase in impact strength with increasing the clay content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1562–1570, 2002