Mass transfer and holdup in gas-liquid cocurrent flow packed beds containing water-repellent particles

Water-repellent particles were prepared by spraying polytetrafluoroethylene (PTFE) on activated carbon. Gas-liquid volumetric mass transfer coefficient and holdup were determined in gas-liquid cocurrent upflow and downflow packed beds from the measurements of gas desorption and volume, respectively. As the PTFE loading increased, the gas-liquid volumetric mass transfer coefficients in both upflow and downflow modes were enhanced. Gas holdup in the upflow mode increased with the PTFE loading, while the dynamic liquid holdup in the downflow mode decreased. The enhancement of the mass transfer rate from gas to liquid can be explained by the effect of water-repellency on the surface of activated carbon.     

新型端基型疏水缔合水溶性聚合物的合成及其性能

提出了端基型疏水缔合水溶性聚合物的分子结构设想,合成了新型端基型疏水缔合水溶性聚合物,克服了疏水基团在分子链中无规则分布的缺点;疏水基团位于分子链的两端,受分子链弯曲屏蔽的影响作用比一般的疏水缔合水溶性聚合物的影响小,使疏水缔合作用更加明显。评价了疏水端基大小和浓度对聚合物性能的影响和聚合物溶液的盐增粘性、抗温性、抗剪切性以及溶液中聚合物与外加表面活性剂的相互作用。结果表明,在水溶性聚合物分子的两端接上了不同的疏水基团,形成端基型疏水缔合水溶性聚合物,该类聚合物结构清楚,相对分子质量确定,并具有很好的增粘性、抗温性、抗盐性和抗剪切性;当疏水端基的质量分数为1.2%时,溶液的流出时间最长,说明缔合作用最强。     

两种聚合物在多孔介质中的渗流特性

疏水缔合水溶性聚合物(HAWP)是大分子链中含有少量疏水基团的水溶性聚合物，在模拟某一油藏条件下，研究了HAWP和ASG两种不同类型聚合物溶液在多孔介质中的渗流特性。研究结果表明，由于HAWP分子疏水基团发生分子间缔合作用，形成动态物理交联网络，HAWP溶液表现出很强的流度控制能力；在远离注入端的多孔介质中，HAWP溶液比ASG溶液具有更高的抗冲刷性和降低孔隙介质渗透率的能力。两种聚合物溶液在多孔介质中表现出的不同渗流特性与聚合物的分子结构有密切关系。     

三氟甲基基团的主侧链位置对聚芳醚酮材料性能影响的研究

通过亲核缩聚法制得三氟甲基基团分别位于主链位置和侧链位置的聚芳醚酮,通过1H-NMR确定了两种聚芳醚酮的结构。分析DSC结果发现,三氟甲基基团位于主链位置的聚芳醚酮的玻璃化转变温度（Tg）为166oC,三氟甲基基团位于侧链位置的聚芳醚酮的玻璃化转变温度（Tg）为139oC,因主链的三氟甲基增加了主链的刚性,使得三氟甲基基团位于主链位置的聚芳醚酮具有更高的玻璃化转变温度。三氟甲基基团相对位置不同的聚芳醚酮材料的5%热失重温度均在490oC以上,都表现出良好的热稳定性。分析水接触角结果发现,三氟甲基基团位于主链位置的聚芳醚酮的水接触角为91o,三氟甲基基团位于侧链位置的聚芳醚酮的水接触角为113o,因三氟甲基基团位于侧链位置的聚芳醚酮的氟原子在经过高温处理后更易向薄膜表面迁移,薄膜表面的表面能降低,表现出更加优异的疏水性能。     

超疏水绝缘涂层制备与防冰、防污研究现状

输电线路的覆冰灾害是电力系统最严重的威胁之一。超疏水绝缘涂层具有强憎水性和低表面能,因而具有提高输电线路防覆冰与防污性能的潜力。对超疏水绝缘涂层的制备方法及其在电力系统中的应用研究现状进行概述,介绍超疏水绝缘涂层的电绝缘性、化学稳定性、机械稳定性等基本性能,对比分析超疏水绝缘涂层与普通憎水性绝缘涂层的防覆冰与防污性能,阐明超疏水绝缘涂层在延缓绝缘子覆冰方面的机理。此外,对超疏水绝缘涂层在耐腐蚀等领域的应用研究现状也进行了介绍。提出在未来输电线路超疏水绝缘涂层的研究中,应重点关注制备方法的经济性、涂层表面的长效性以及防污闪机理等方面的关键问题,提升涂层的综合性能。     

The optimum synergistic effect of amphiphilic polymers and the stabilization mechanism of a crude oil emulsion

The amphiphilic polymers (APs) possess both thickening and emulsifying properties that were optimized by the combination of different APs. The properties and synergistic mechanisms of the combination system, consisting of HAP-L and HAP-S, were studied and optimized according to their proportion at various concentrations, temperatures, salinities, and shear rates. Furthermore, various methods were applied to study the emulsification properties of the combination system. The results show that the viscosity, salt resistance, temperature resistance, and shear resistance of the combination system are greatly improved. It is noteworthy that the combined system displays the optimized properties when the mass ratio of HAP-S and HAP-L is 3:2. Under that circumstance, the emulsions also turn to be more stable and display more uniform particle distribution. After combination, more hydrophobic groups participate in the intermolecular association, and the structure of the network is enhanced. Therefore, a combination of various APs can be used as an effective approach to improve the viscosity and emulsification capability of APs for oil recovery.     

Unidirectional Wetting in the Hydrophobic Wenzel Regime

Unidirectional wetting surfaces can cause liquid droplets to flow/move in one direction while pinning them in the other directions, a feature that is useful for biosensing, adhesives, thermal management, and microfluidics. Such surfaces can be fabricated by employing structurally or chemically asymmetric nanostructures. While unidirectional wetting in the hydrophobic Wenzel regime had previously been observed on surfaces decorated with chemically asymmetric nanostructures, it has yet to be demonstrated on structurally asymmetric nanostructures. Based on the current understanding of the phenomenon, this can only be achieved using highly bent nanowires. Here, evidence to the contrary is provided by showing that mildly bent nanowires can also bring about unidirectional wetting in the hydrophobic Wenzel regime, even for contact angles beyond the superhydrophobic limit. Using NaCl precipitation, the unidirectional wetting mechanism is analyzed on a nanoscale level and it is found that the criteria for unidirectional wetting to take place in the hydrophobic Wenzel regime are different from that in the hydrophilic Wenzel regime. Moreover, it is revealed that slight wetting in the pinned direction can be caused by large scale deformation of high aspect ratio nanostructures during droplet spreading, which may be part of the reason behind previous observations of near‐unidirectional wetting on bent nanowires with high aspect ratios.     

疏水性非微珠型建筑反射隔热涂料性能研究

建筑外墙和屋面用疏水性非微珠型建筑反射隔热涂料采用纳米隔热粉和纳米辐射粉作为主要功能性填料,可用普通建筑涂料生产工艺生产,产品具有良好的隔热、疏水性,且能减少雨水的渗透,提高建筑节能的效果.     

超疏水氟硅防污涂料的制备及性能研究

以自制氟硅嵌段聚合物为成膜物质,添加纳米SiO2、颜填料和助剂,制成低表面能防污涂料。通过考察树脂、纳米SiO2及颜填料含量对涂料性能的影响,确定了各自的最佳用量:树脂35%、纳米SiO210%和颜填料5%。试验结果表明:所制备的涂层外观光滑、平整,附着力1级,铅笔硬度HB,抗冲击性54 cm。水接触角152.25°,达到了超疏水性能。