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两组份互穿网络聚合物的合成研究 总被引:1,自引:0,他引:1
以蓖麻油聚氨酯和聚醚聚氨酯的不同重量比与光敏剂、催化剂、稀释剂、促进剂所组成的多相体系为反应物,分别在紫外光照射和加热的条件下合成网络Ⅰ和网络Ⅱ的互穿网络聚合物(IPN)。改变网络Ⅱ聚醚聚氨酯中各组份的摩尔比制得系列样品。红外光谱,应力-应变曲线和动态力学性能测定发现,样品的力学性能与两组份重量比和网络Ⅱ中不同组成都存在着一定关系。这些结果,为该体系IPN的合成和应用提供了一定依据。 相似文献
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Differential scanning calorimetry has been used to study the kinetics of epoxy-amine curing reaction between diglycidyl ether of 4,4'-bisphenol and aromatic amines with different electron-withdrawing/-donating substituents. The substituents include -NO2, -CN, -OCH3, -OH, and -CH3 groups. An advanced isoconversional method has been employed to determine the effective activation energy of the respective processes. An attempt has been made to link the experimental values with the results of quantum chemistry calculations. It has been found that regardless of the electron-withdrawing/-donating properties the presence of a substituent of a large negative charge in the ortho position causes an increase in the activation energy to approximately 100 kJ mol-1 from the normally observed values of 50-60 kJ mol-1. 相似文献
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优化了碱性阴离子交换膜燃料电池(AAEMFC)使用的气体扩散电极(GDE),发现催化层中PTFE含量与催化剂担载量对电池性能与其电化学动力学特征影响很大.采用i-V曲线,开路电压,电池内阻与在线的电化学阻抗谱与动力学分析,评估了所制GDE的电化学性能.在所研究的AAEMFC电极催化层中,PTFE的最佳含量是20%,Pt载量对膜电极三相界面、催化层导电性与催化剂利用率的影响极大.当制备的GDE催化层中Pt/C的Pt载量为1.0mg/cm2,PTFE含量为20%时,AAEMFC的峰电流密度在50oC达到了213mW/cm2.兼顾Pt催化剂的利用率与成本,在没有明显影响电池性能的情况下,Pt的担载量可降至0.5mg/cm2. 相似文献
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非饱和土吸力的温度性质 总被引:6,自引:1,他引:5
根据热力学理论,讨论非饱和土中的土吸力随温度变化的情况,得到在一般情况下非饱和土中的土吸力随着温度增加而线性减小的规律. 相似文献
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Saurabh Soni Gang Ye Jueting Zheng Yanxi Zhang Andika Asyuda Michael Zharnikov Wenjing Hong Ryan C. Chiechi 《Angewandte Chemie (International ed. in English)》2020,59(34):14308-14312
This study describes the modulation of tunneling probabilities in molecular junctions by switching one of two parallel intramolecular pathways. A linearly conjugated molecular wire provides a rigid framework that allows a second, cross‐conjugated pathway to be effectively switched on and off by protonation, affecting the total conductance of the junction. This approach works because a traversing electron interacts with the entire quantum‐mechanical circuit simultaneously; Kirchhoff's rules do not apply. We confirm this concept by comparing the conductances of a series of compounds with single or parallel pathways in large‐area junctions using EGaIn contacts and single‐molecule break junctions using gold contacts. We affect switching selectively in one of two parallel pathways by converting a cross‐conjugated carbonyl carbon into a trivalent carbocation, which replaces destructive quantum interference with a symmetrical resonance, causing an increase in transmission in the bias window. 相似文献