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31.
Polyphenylsilsesquioxane (PPSQ) was incorporated into an epoxy resin to prepare organic–inorganic composites, and two strategies were adopted to afford composites with different morphologies. Phase separation induced by polymerization occurred in the physical blending system. However, nanostructured composites were obtained when a catalytic amount of aluminum triacetylacetonate was added to mediate the reaction between PPSQ and diglycidyl ether of bisphenol A (DGEBA). The intercomponent reaction significantly suppressed the phase separation on the micrometer scale. Organic–inorganic composites with different morphologies displayed quite different thermomechanical properties. Both differential scanning calorimetry and dynamic mechanical analysis showed that the nanostructured composites possessed higher glass‐transition temperatures than the phase‐separated composites with the same loading of PPSQ, although the intercomponent reaction between PPSQ and DGEBA reduced the crosslinking density of the epoxy matrix. This result was ascribed to the presence of nanosized PPSQ domains in the nanostructured composites, which acted as physical crosslinking sites and thus reinforced the epoxy networks. The nanoreinforcement of the PPSQ domains afforded the enhanced dynamic storage modulus for the nanostructured composites in comparison with the phase‐separated composites with a PPSQ concentration less than 15 wt %. In terms of thermogravimetric analysis, the organic–inorganic composites displayed improved thermal stability and flame retardancy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1093–1105, 2006 相似文献
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Zhe Wang Hongzhe Ni Chengji Zhao Xianfeng Li Tiezhu Fu Hui Na 《Journal of Polymer Science.Polymer Physics》2006,44(14):1967-1978
The sulfonated poly(ether ether ketone sulfone) (SPEEKS)/heteropolyacid (HPA) composite membranes with different HPA content in SPEEKS copolymers matrix with different degree of sulfonation (DS) were investigated for high temperature proton exchange membrane fuel cells. Composite membranes were characterized by Fourier transfer infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). FTIR band shifts suggested that the sulfonic acid groups on the copolymer backbone strongly interact with HPA particles. SEM pictures showed that the HPA particles were uniformly distributed throughout the SPEEKS membranes matrix and particle sizes decreased with the increment of copolymers' DS. The holes were not found in SPEEKS‐4/HPA30 (consisting of 70% SPEEKS copolymers with DS = 0.8 and 30% HPA) composite membrane after composite membranes were treated with boiling water for 24 h. Thermal stabilities of the composite membranes were better than those of pure sulfonated copolymers membranes. Although the composite membranes possessed lower water uptake, it exhibited higher proton conductivity for SPEEKS‐4/HPA30 especially at high temperature (above 100 °C). Its proton conductivity linearly increased from 0.068 S/cm at 25 °C to 0.095 S/cm at 120 °C, which was higher than 0.06 S/cm of Nafion 117. In contrast, proton conductivity of pure SPEEKS‐4 membrane only increased from 0.062 S/cm at 25 °C to 0.078 S/cm at 80 °C. At 120 °C, proton conductivity decreased to poor 0.073 S/cm. The result indicated that composite membranes exhibited high proton conductivity at high temperature. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1967–1978, 2006 相似文献
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荧光光度法直接测定高纯氧化钕中的痕量镨和铈 总被引:2,自引:0,他引:2
李义久 《理化检验(化学分册)》1998,34(5):198-199,201
使用P-ELS50荧光光谱仪,在盐酸介质中,用同一激发波长激发,分别测定Pr(Ⅲ)(nm)和Ce(Ⅲ)(356nm)发射峰强度。 相似文献
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制备了用巯基丁二胺铜(CuL)修饰的金电极并用作HIV-p24抗原蛋白(简称p24)免疫检测的化学传感器。CuL通过单层自组装固定在金电极表面,其覆盖率为1.02×10-11mol.cm-2,在含有1.0 mmol.L-1过氧化氢并在pH 6.2的磷酸盐缓冲溶液中,制备的校正曲线的线性范围为0.5-150μg.L-1p24对相应的伏安响应,方法的检出限为0.2μg.L-1。在10μg.L-1p24浓度水平作精密度试验,得RSD值为3.5%,于试样中分别加入5,15,20及30μg.L-1p24进行回收率试验,所得结果在98%-102%之间。此方法毋需另加电子传递媒介体。应用此方法于临床血清分析,所得结果与放射性免疫法的结果一致,且所得RSD值均小于0.3%。 相似文献
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液相色谱-蒸发光散射-电喷雾离子阱质谱法测定硫酸异帕米星及其有关物质 总被引:3,自引:0,他引:3
建立高效液相色谱-蒸发光散射检测(HPLC-ELSD)法测定硫酸异帕米星及其有关物质的含量,并采用高效液相色谱-电喷雾离子阱质谱(HPLC-MSn)联用,鉴定硫酸异帕米星中的有关物质.采用岛津Shim-VPODS色谱柱,流动相为005 mol/L五氟丙酸溶液甲醇(65∶35),流速为10 mL/min,漂移管温度为50℃,雾化气体压力为35×105 Pa,在正离子检测方式下,用电喷雾离子阱质谱法对异帕米星中的杂质进行多级质谱分析.异帕米星和杂质分离良好.异帕米星在70~1830 mg/L的范围内呈较好的线性关系(r=09999),异帕米星的重复性实验RSD=12%;检出限为11 mg/L,结合多级质谱裂解初步推断异帕米星中主要一个未知杂质是异帕米星分子中3位NH2与异丝氨酸结合失去一个分子H2O所得的两分子异丝氨酸取代物.方法快速、简便,结果准确可靠,重现性好. 相似文献
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