原位生成Al2O3、TiB2和Al3Ti/Al复合材料的热循环行为

本文研究了Al-TiO2-B系原位生成Al2O3、TiB2和Al3Ti/Al颗粒增强铝基复合材料的热循环行为，研究结果表明了纯铝及B／TiO2摩尔比分别为0、1和2的颗粒增强铝基复合材料的热循环行为具有以下结果，纯铝和复合材料热循环后均产生了残余应变和滞后环；Al-TiO2-B系列复合材料热循环应变的各项指标均比纯铝基体大大降低，且具有较小的内耗功和较好的热稳定性，可以预测其具有较高的热疲劳寿命，热循环曲线能很好的评估复合材料在温度循环变化的环境中工作时的热稳定性和热疲劳。     

Poly(butylene terephthalate)/organoclay nanocomposites prepared by in situ interlayer polymerization and its fiber (II)

Intercalated nanocomposites with poly(butylene terephthalate) (PBT) incorporated between the montmorillonite layers were synthesized from dimethyl terephthalate and 1,4-butane diol by using an in situ interlayer polymerization. The PBT nanocomposites were melt-spun at different organoclay contents to produce monofilaments. The samples were characterized by using wide angle X-ray diffraction, electron microscopy, thermal analysis, and tensile testing. The extent of the clay layer in the PBT was confirmed by using X-ray diffraction and electron microscopy, and the clay layer was found to be highly dispersed on a nanometer scale. The addition of only a small amount of organoclay was enough to improve the thermo-mechanical properties of the PBT hybrid fibers. The hybrids were extruded with various draw ratios (DRs) to examine the tensile mechanical property of the fibers. At DR=1, the ultimate tensile strength of the hybrid fibers increased with the addition of clay up to a critical content and then decreased. However, the initial modulus monotonically increased with increasing amount of organoclay in the PBT matrix. When the DR was increased from 1 to 6, for example, the strength and the initial modulus values of the hybrids containing 3 wt% organoclay decreased linearly.     

加氢催化剂的器外再生

介绍了国内外再生技术的发展状况，对比器内和器外再生技术的优缺点以及催化剂活性恢复率的差异，说明器外再生技术是催化剂再生的发展方向。     

In situ ESR of CrH-ZSM-5 up to 500°C in flowing gas containing O2, H2O,CCl4, NO,NO2, and C3H6

A flow cell was used for the in situ ESR monitoring of the state and reactivity of chromium ions in Cr-ZSM-5. Calcination of Cr(NO₃)₃/NH₄-ZSM-5 in air at 500°C is accompanied by migration of chromium ions inside the zeolitic channels and stabilization ofisolated Cr⁵⁺ cations near lattice A1³⁺ ions. Calcination of Cr-ZSM-5 at 750°C leads to a gradual disappearance of the isolated Cr⁵⁺ cations and formation of -Cr₂O₃ microcrystals. All the Cr⁵⁺ cations are accessible to gas-phase molecules: O₂ strongly broadens the dipole-dipole signal; H₂O sorption increases the local crystal field symmetry; admission of CCl₄ results in a small change of the Cr⁵⁺ local coordination; strongly stabilized complexes on Cr-ZSM-5 are observed upon sorption of either NO or NO₂. The sorption of C₂H₆ on Cr-ZSM-5 at 20°C is accompanied by a gradual reduction of the Cr⁵⁺ sites. At 500°C in [C₃H₆ + O₂ + He] flow, even at a large excess of oxidant, the reduction of a noticeable part of Cr⁵⁺ ions takes place. At 400°C, in the same gas mixtures, a deeper reduction of Cr⁵⁺ occurs. Closer to stoichiometric conditions, in a [C₃H₆ + NO + He] flow with 120% excess of oxidant the Cr⁵⁺ is completely reduced at 500°C. The oxidation of propene is accompanied by coke deposition on the surface of the catalyst. The implications of the results are discussed.     

熔铸-原位反应法生成α-Al2O3晶须的形貌及结晶方向

利用熔铸－原位反应法制备TiC/Al复合材料时，发现Ti-C-Al反应块表面存在大量的Al2O3晶须，晶须的形貌包括长而直的板状和串珠状，取决于反应进行时铝熔体的温度，当铝熔体温度低于900℃时，形成板状晶须，而当铝熔体温度高于900℃时，形成串珠状的晶须，其原因是由于较高的铝熔体温度加剧了TiC原位反应的放热，热起伏的结果致使部分α－Al2O3晶须异常长大，X射线衍射和透射电镜分析确认晶须为α－Al2O3，其形貌以直板状为主，电子衍射花样斑点显示其结晶方向为[0002]。     

聚甲基丙烯酸甲酯／纳米SiO2复合粒子的制备与表征

采用甲基丙烯酸-3-甲氧基硅丙酯（MPs）对分散于甲基丙烯酸甲酯（MMA）中的纳米SiO2粒子进行偶联改性，得到了表面改性的纳米SiO2单体分散液，用原位悬浮聚合方法制备了不同SiO2含量的PMMA／纳米SiO2复合粒子。通过红外光谱、透射电镜、差示扫描量热分析和热重分析等方法对制备的纳米复合粒子进行了表征，结果表明，纳米SiO2粒子在PMMA中分散良好；MMA可通过与MPS的共聚而有效地接枝到SiO2粒子表面，当SiO2含量为6．6％（质量分数，下同）、MPS用量为0．06g／gSiO2时，其接枝率可达73．8％；同时，纳米SiO2的引入可提高PMMA的耐热性能，当Si02含量为14.7％时，其玻璃化转变温度和最大热分解速率时的温度分别提高了11．8℃和18．8℃。     

聚苯胺/涤纶导电织物再掺杂及洗涤性能的研究

采用现场吸附聚合法制备了聚苯胺 /涤纶导电织物 ,采用不同种类的酸对其进行再掺杂 ,研究了酸的种类对织物导电性能的影响 ,并对导电织物进行了洗涤实验及洗涤牢度实验。结果表明 :无机酸对导电织物的掺杂效果优于大多数有机酸。导电涤纶织物的导电性能受洗涤液酸碱度的影响 ,其中碱性洗涤液使导电性能降低 2个数量级 ,酸性洗涤液使导电性能下降 1个数量级 ,而且聚苯胺在涤纶织物表面具有良好的附着性     

Competitive Reaction During Decomposition of Hexachlorobenzene Over Ultrafine Ca–Fe Composite Oxide Catalyst

The decomposition of hexachlorobenzene (HCB) has been investigated over ultrafine Ca–Fe composite oxide catalyst (Ca/Fe atomic ratio was 3.4), CaO and α-Fe₂O₃ by using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Adsorption experiments on the surface of oxides monitored by in situ DRIFTS showed that partial oxidation products, i.e., phenolate and acetate species were formed on the surface of Ca–Fe composite oxide. The further studies indicated that Ca–Fe composite oxide catalyst was easier to induce the rupture of C–Cl bond and C–C bond of aromatic rings. The best catalytic activity of Ca–Fe composite oxide may be related to the acidity, which was determined by NH₃–TPD. The products after reaction have been analyzed by XRD and chloride selective electrode. Ca–Fe composite oxide exhibited the highest extent of mineralization for organic chlorine among the different oxides tested. The combined results of current and previous experiments demonstrated that two competitive reactions took place during the decomposition process of HCB: (1) hydrodechlorination resulting in the formation of lower chlorinated benzenes and (2) oxidation of aromatic rings leading to the rupture of aromaticity and the formation of oxidation products. The latter is the major process in the coexisted competitive reaction. A possible decomposition pathway was discussed.     

Thermotropic liquid crystalline polymer (Rodrun LC5000)/polypropylene in situ composite films: rheology, morphology, molecular orientation and tensile properties

In situ composite films were prepared by a two-step method. First, polypropylene and thermotropic liquid crystalline polymer (TLCP), Rodrun LC5000 (80 mol% p-hydroxy benzoic acid (HBA)/20 mol% polyethylene terephthalate (PET)), were melt blended in a twin-screw extruder and then fabricated by extrusion through a mini-extruder as cast film. Rheological behavior of the blends, morphology of the extruded strands and films, and tensile properties of the in situ composite films were investigated. Rheological behavior of the blends at 295 °C studied using a plate-and-plate rheometer revealed a substantial reduction of the complex viscosity with increasing TLCP content, and all specimens exhibited shear thinning behavior. Over the angular frequency range of 0.6-200 rad/s, the viscosity ratio (dispersed phase to matrix phase) was found to be very low, in the range of 0.03-0.07. Morphologies of the fracture surfaces of the blend extrudates and the film surfaces etched in permanganic solution were investigated by scanning electron microscope (SEM). The TLCP droplets in the extruded strands were seen with a progressive deformation into fibrillar structure when TLCP content was increased up to 30 wt%. In the extruded films, TLCP fibrils with increasing aspect ratio (length to width) were observed with increasing TLCP concentration. Orientation functions of each component were determined by X-ray diffraction using a novel separation technique. It was observed that the Young's modulus in machine direction of the extruded film was greatly improved with increasing TLCP loading, due to the increase in fiber aspect ratio and also molecular orientation.     

Thermal cure monitoring of phenolic resole resins based on in situ fluorescence technique

The thermal curing reaction of two phenolic resole resins is monitored using the fluorescence technique. The intrinsic fluorescence can be used as an indicator for cure monitoring for the first resole. As the thermal curing proceeds, the intrinsic fluorescence intensity of the resole resin decreases and exhibits a few nanometers of redshift. The fluorescence intensity of the emission maxima is correlated with the conversion measured by differential scanning spectroscopy. A linear correlation is found at three different temperatures. The intrinsic fluorescence cannot always be used for monitoring the curing process of phenolic resole resins. Thus, three intramolecular charge transfer compounds and two organic donor–π‐acceptor salts are selected and applied for the cure monitoring of the second phenolic resole resin. As the curing reaction proceeds, the fluorescence emission spectra of the probes exhibit a blue spectral shift and the intensity changes because of environmental changes. An intensity ratio method is applied in which the ratios of the low‐ to high‐intensity changes in the emission bands are used to determine the degree of the curing process. There is a smooth correlation between the intensity ratio method and the degree of cure. The method enables one to follow the changes in the polymer structure at low and intermediate degrees of the curing process (below 70%) and obtain comparable results from different types of probes during the same curing process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1773–1780, 2002