Oligo(ethylene oxide) side‐chain steric screening effects on conductimetric properties of grafted poly(4‐vinylpyridinium) salts in aqueous solutions

A set of poly[N‐oligo(ethylene oxide)yl 4‐vinylpyridinium tosylate] (P4VOEOOTs) has been prepared by spontaneous polymerization of 4‐vinylpyridine. This method gives a grafted polyelectrolyte having a positive charge on every backbone pyridinic moiety. The P4VP15Ts, P4VP164Ts, P4VP350Ts and P4VP750Ts aqueous solution conductivities were determined in the concentration range from 6 × 10^?4 to 10^?2 M at 25 °C. The variation of the conductivity versus concentration of the investigated system exhibits typical polyelectrolyte behaviour. The polyelectrolyte mobility was found to be dependent on the oligo(ethylene oxide) (OEO) side‐chain length. Manning's rod‐like model fails to describe these results. A simple steric effect is proposed to explain the influence of the OEO length. Copyright © 2003 Society of Chemical Industry     

Nd3+:Y0.5Gd0.5VO4晶体生长和基本特性

Nd^3 :Y0.5Gd0.5VO4晶体作为一种新的激光材料，可以用中频感应加热提拉法生长。X射线粉末衍射分析表明它的结构与Nd^3 :YVO4晶体结构相同，它的晶格常数介于YVO4和NdVO4晶格常数之间。用ICP光谱法测定晶体中Nd^3 含量为0．8at％，分凝系数为0．8，与Nd^3 :GdVO4晶体中Nd^3 的分凝系数0．78相当；用称重法测定其密度为5．00g／cm^3；用稳态纵向热流法测出其室温热导率为12．5W／mK。实验表明Nd^3 :Y0.5Gd0.5VO4晶体有希望作为高功率ID泵浦激光晶体材料。     

长距离管输对3号喷气燃料导电性能和清洁性能的影响

分析了长距离管输后3号喷气燃料电导率严重衰减的原因和补加抗静电剂后对3号喷气燃料电导率和水反应指标的影响。对比了成品油长距离管输和喷气燃料馏分长距离管输对3号喷气燃料电导率和水反应指标的影响，并对比了两种管输方式的优缺点，提出对3号喷气燃料的管输建议。3号喷气燃料的长距离管输，优先采用喷气燃料馏分油管输在末端加注抗静电剂的方式；需兼顾汽运时，宜采用成品油管输并在末端根据电导率衰减情况，最小量补加抗静电剂的方式，以获得较高的成功率和较好的经济效益。     

Improving narrow bandgap a-SiGe:H alloys grown by hot-wire chemical vapor deposition

We have improved the electronic properties of narrow-bandgap (Tauc gap below 1.5 eV) amorphous-silicon germanium alloys (a-SiGe:H) grown by hot-wire chemical vapor deposition (HWCVD) by lowering the substrate temperature and deposition rate. Prior to this work, we were unable to grow a-SiGe:H alloys with bandgaps below 1.5 eV that had photo-to-dark conductivity ratios comparable with our plasma-enhanced CVD (PECVD) grown materials [B.P. Nelson et al., Mater. Res. Soc. Symp. 507 (1998) 447]. Decreasing the filament diameter from our standard configuration of 0.5 mm to 0.38 or 0.25 mm provides first big improvements in the photoresponse of these alloys. Lowering the substrate temperature from our previous optimal temperatures (T_sub starting at 435 °C) to at 250 °C provides additional photo-to-dark conductivity ratio increasing by two orders of magnitude for growth conditions containing 20–30% GeH₄ in the gas phase (relative to the total GeH₄+SiH₄ flow).     

非稳定井流模型的半解析解

为了提高非稳定渗流计算的计算精度 ,通过数学分析得到了水位传导系数随时间变化时 ,一类非稳定渗流井流模型的半解析解 ,并进行了计算比较     

掺杂聚苯胺导电膜的制备及对核设施表面铀的去污

制备了掺杂导电聚苯胺可剥离膜，首次采用涂膜、电解联用去污方法，进行涂膜电解去除渗透到核设施金属材料内部形成氧化物的铀。在膜中，聚苯胺、盐酸、EDTA-2Na含量各为4％、0．5％～1%、1％；电解电压2．3V、电解时间25min～30min时，其去污率可达99％，优于其它的方法。     

Thermodynamic and Transport Properties of Liquid HFC-227ea

The thermal conductivity and heat capacity of liquid 1,1,1,2,3,3,3-hepta-fluoropropane (HFC-227ea) have been studied by a high-frequency thermal-wave method over the temperature range of 294 to 345 K at pressures up to 2.8 MPa. The purity of the samples used throughout the measurements is 99.99 mol%. The experimental uncertainties of the thermal conductivity and heat capacity measurements were estimated to be within ±1.5 and ±2%, respectively. The thermal conductivity of HFC-227ea in the liquid phase decreases as temperature increases, while the pressure has an opposite effect.     

三维连通网络陶瓷的电磁特性Ⅱ电磁参数的影响因素

通过对具有不同骨架L径、陶瓷浆料组分在不同温度下烧结的三维连通网络陶瓷的电导率和电磁参数的测量,研究了对这种网络结构材料电磁参量的影响因素.结果表明,当三维连通网络陶瓷的电导率为10-4＜σ＜101S/cm时,其电损耗及感应磁损耗较大.三维连通网络陶瓷在高温下有较大的介电损耗特性,使其成为耐高温电吸波材料的理想选择.     

CMS/TiO2杂化材料电流变液的制备及其性能

利用特殊的溶胶凝胶方法原位制备了改性淀粉与无机钛氧化物杂化型电流变材料。实验表明,在强电场下其电流变效应比相同组份的淀粉、二氧化钛混合型电流变液有显著提高,直流电场4 kV/mm,剪切速率5 s-1时,静态剪切屈服强度可达4000 Pa以上。同时,抗沉降性明显改善,静置100 h几乎不沉淀。此外,温度效应也获得一定的优化,在10 ℃~90 ℃的工作温度范围内力学性能保持良好,70 ℃时剪切强度达到最大值。     

功率电子器件用AlN陶瓷基板的研制

阐述了AlN陶瓷的烧结原理 ,分析了烧结工艺参数对大面积AlN基板性能的影响 ,成功研制出了高热导率(190W /m·K)、大面积 (14 0mm× 90mm)、翘曲度为 2 0 μm/5 0mm的AlN陶瓷基板。