Methacryloxyethyl phosphate‐grafted expanded polytetrafluoroethylene membranes for biomedical applications

Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2‐butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGy h^?1), monomer concentration (1–40 %) and solvent were studied and the modified membranes were characterized by weight increase, X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the C? F (ePTFE membrane) and the C? C (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non‐solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. Copyright © 2005 Society of Chemical Industry     

在湿陷性黄土地区对混凝土夯扩桩的检测

对夯扩桩在豫西湿陷性黄土地区的应用和可行性分析与检测。     

话音ATM交换的实现─—ATM论坛电路仿真系列建议

近年来，随着ATM主干网络的建设和发展，研究ATM对现有通信业务的支持方式和适配技术是目前ATM技术研究的热点之一。话音ATM交换在降低话音通信成本和简化网络操作环境等方面提供了大量的技术手段，并且支持在单一网络环境中的多种综合业务传输。ATM论坛制定了电路仿真系列建议，话音ATM交换的技术已经基本成熟。文章通过对话音ATM交换在实现和优化方面的技术进行分析，并提出一种基于NativeModeATM的话音通信方式。     

接触器特征参数测试仪

本文详细介绍了微机型接触器特征参数测试仪工作原理，软硬件及调试、运行和故障处理。     

Crystallization of poly(3‐hydroxybutyrate) by exfoliated graphite nanoplatelets

Poly(3‐hydroxybutyrate) (PHB) has been shown to be efficiently nucleated by exfoliated graphite nanoplatelets (xGnP). The nucleating effect of xGnP was investigated using differential scanning calorimetry, optical microscopy and atomic force microscopy. Nonisothermal crystallization of PHB from the melt required lower activation energies for PHB containing 1 wt % and 3 wt % xGnP (?214 and ?102 kJ/mol respectively) than for pure PHB (?60 kJ/mol). A kinetic study of the PHB/xGnP crystallization employing a modified form of the Avrami equation revealed that the presence of xGnP increased the PHB crystallization temperature, as well as the crystallization rates, and generated smaller and more numerous spherulites. Optical microscopy and atomic force microscopy confirmed the incorporation of xGnP into the lamellar structure of the PHB spherulites and provided insight into the influence of xGnP on spherulite size and lamellae thickness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

聚乙烯/石墨阻燃复合材料的研究

研究了石墨、可膨胀石墨、膨胀石墨 /聚乙烯复合材料的阻燃性能。结果表明 ,石墨具有一定的阻燃作用 ,可膨胀石墨具有良好的阻燃效果。但可膨胀石墨填充的复合材料力学性能较差     

细鳞片石墨化学氧化法制备可膨胀石墨技术问题探讨

采用分步氧化法制备了80目细鳞片可膨胀石墨。通过L9（3^4）正交试验确定了最佳工艺条件。在液固比-5：1，C：KMnO4=1：0．12，Ⅰ H2SO4：Ⅱ H2SO4=4：1，H2SO4：H2O2=12：1（均为质量比g／g）条件下获得膨胀容积为290mL／g。对制备过程中液固比、硫酸浓度、双氧水的加入方式、可膨胀石墨烘手温度、原料粒度等因素对膨胀容积的影响以及可膨胀石墨的稳定性的改善方法进行了探讨。     

带轴涡轮转子在立式超速试验台上的超速试验

对带轴涡轮转子提供了可行的试验处理方法 ,并成功地进行了超速试验     

膨胀石墨的饱和吸附量与微观结构的关系

采用不同的方法测定膨胀石墨对不同油质的饱和吸附量,来探讨膨胀石墨的结构与饱和吸附量的关系.由扫描电镜可知,膨胀石墨具有较大的比表面积,其孔结构是以中、大孔为主;蠕虫石墨的表面结构与其内部结构不同,其内部为典型的片层结构.通过观察石墨内部孔结构特征变化,可以分析膨胀石墨对油的去除效率以及影响因素.     

Mechanism of Fume Suppression and Performance on Asphalt of Expanded Graphite for Pavement under High Temperature Condition

Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy(FT-IR), X-ray diffraction(XRD), scanning electron microscopy(SEM) and comprehensive thermal analysis(TG, DSC). The experimental results confirm that asphalt which is mixed with expandable graphite will expand in the process of hot mix, and the expanded graphite layer will swell by the light component in the asphalt. The light component in the asphalt and PAHs adsorption on expanded graphite surface or part of the plug in the expanded graphite layer between plates made nucleation crystallization growth. And the Van der Waals force and the bonding of the lattice can effectively restrain the asphalt fume release. Meanwhile, the expanding agent with oxidative can spread into the asphalt, leading to asphalt oxygenated and plastic abate, while the ductility decreases. Expanded graphite, SBS modifier and environment- friendly plasticizers are used to composite modified asphalt. According to asphalt fume release experiment, normal test of asphalt performance, Brookfield viscosity test, RTFOT test and asphalt mixture tests(high temperature stability, low temperature stability, water stability), it has been proven that the modified asphalt's performance is better than that of matrix asphalt and equivalent to that of SBS modified asphalt. Furthermore, it has good fume suppression effect.