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61.
62.
In this paper, debonding phenomena between carbon fiber reinforced polymer (CFRP) strips and masonry support were investigated on the basis of single-lap shear tests, considering different dimensions of the bond length. To capture the post-peak response of the CFRP–masonry joint, the slip between the support and the reinforcement strip was controlled using a clip gauge positioned at the end of the reinforcement. The tests were simulated by means of a finite element model able to capture the post-peak snap-back behavior due to the failure process. The numerical model is based on zero-thickness interface elements and on a proper non-linear cohesive law. The comparison between experimental and numerical results was performed in terms of overall response, measured by both the machine stroke and the clip gauge positioned at the free end of the reinforcement. The cases of effective bond length greater and lesser than the minimum anchorage length, suggested by the CNR Italian recommendation, were considered. 相似文献
63.
An effective electron-injection layer (EIL) is crucial to the development of highly efficient polymer light-emitting diodes (PLEDs) using stable, high work-function aluminium as the cathode. This work presents the first investigation using hydroxyethyl cellulose (HEC), filled with chelate complexes [(CH3COO)2-M, EDTA-M; M: Ca2+, Mg2+], as an electron-injection layer (EIL) to fabricate multilayer polymer light-emitting diodes (ITO/PEDO:PSS/HY-PPV/EIL/Al) by spin-coating processes. Devices based on HEC doped with EDTA-M provided the best performance. The maximum luminance and maximum current efficiency of polymer light-emitting diodes with EDTA-Ca in an HEC layer were 7502 cd/m2 and 2.85 cd/A, respectively, whereas those with EDTA-Mg were 8443 cd/m2 and 3.12 cd/A, which was approximately seven- to eight-fold of that without EIL. This performance enhancement was attributed to electron donation from the chelator that reduces metal cations to a “pseudo-metallic state”, enabling it to act as an intermediate step to facilitate electron injection. The results demonstrate that chelates of bivalent cations with EDTA can potentially serve as electron-injection materials for optoelectronic applications. 相似文献
64.
Xiaopeng Yue Yongjian Xu Nina Gou Hongkui Li 《Polymer-Plastics Technology and Engineering》2015,54(6):639-646
A long fatty side chain was introduced into the macromolecule of hydroxyethyl cellulose (HEC) via esterification reaction. The hydrophobicity of hydroxyethyl cellulose lauric acid ester (HECLAE) was enhanced in comparison with HEC. The obtained HECLAE was used as macromolecular coupling agent in poly (butylene succinate)/wood flour composites and exhibited a positive influence on improving the mechanical performance of composites. Besides, HECLAE plays a role as a hydrophobic agent in composites. A significant increase in storage modulus (E’) was observed upon the incorporation of treated wood flour. SEM images showed that the dispersion of treated wood flour in PBS matrix was improved. 相似文献
65.
66.
The layer-by-layer (LBL) polyelectrolyte deposited membranes have drawn increasing attention in various applications due to the ease of selective layer formation and their stability and versatility. In this study, the LBL deposition was performed at the inner surface of the polyethersulfone (PES) hollow fiber substrate to form composite nanofiltration (NF) membrane. The semi-dynamic deposition procedure was adopted with the aid of syringes. The newly developed inner deposited (id-LBL) membranes were then tested in NF and forward osmosis (FO) applications and the performance were compared with outer surface deposition as well as some literature data. The id-LBL membranes could not only withstand higher operating pressure but also possess superior hardness rejection especially in high concentration mixed salt solutions (more than 95% rejection to Mg2+ and Ca2+ in a 5000 ppm total dissolved salt (TDS) mixture under 4.8 bar). As for the FO process, with only two layer deposition, the id-LBL membranes also demonstrated significant performance improvement with increased water flux (up to 70 L/m2 h using 0.5 M MgCl2 as draw solution in active layer facing draw solution configuration) and reduced salt leakage (around 0.5 g/m2 h using 1 M MgCl2 draw solution in active layer facing feed water configuration). This study suggests that for hollow fiber substrate, the inner surface is more suitable for the formation of the selective layer via LBL deposition than the outer surface. 相似文献
67.
Fiber reinforced polymer (FRP) can be successfully used to externally strengthen reinforced concrete (RC) bridges where fire is not a primary concern. Nevertheless, common maintenance activity on a bridge deck, such as the laying of bituminous paving, can easily lead the FRP to temperatures higher than the glass transition temperature, Tg. Exceeding Tg does not necessarily imply a drastic reduction in strength and stiffness of the reinforcement. Nevertheless, the softening of the resin implies a drastic reduction in its adhesion properties. Therefore, the efficiency of the strengthening system for existing structures, which mainly depends on the effectiveness of the bond between FRP and concrete, is significantly affected by temperature.The relationships suggested by Italian and American codes in order to evaluate the limit strain for FRP debonding at normal temperature are modified to take into account the effect of high temperature. Then, performances at high temperature of RC bridge decks strengthened with externally bonded FRP plates (EBR) are investigated by considering thermal fields in the structural members which are different from the normal ones. Both fire and the laying of bituminous paving on the decks are considered. In addition, the thicknesses of the slabs and the protective layer are varied to assess their influence on the thermal field in the slabs. The results are discussed with reference to both ultimate and serviceability limit states. 相似文献
68.
69.
Syafikah Huda Paiman Mukhlis A Rahman Khairul Hamimah Abas Azian Abd Aziz Ahmad Fauzi Ismail Mohd Hafiz Dzarfan Othman Juhana Jaafar Mohammad Noorul Anam Mohd Norddin 《化学工程与技术》2019,42(6):1321-1329
Removal by absorptive ceramic membranes can simultaneously absorb and separate metal ions from water. Alumina/yttria‐stabilized zirconia (Al2O3/YSZ) hollow‐fiber membranes, fabricated using phase inversion and sintering process, were deposited with iron oxide by an in‐situ hydrothermal process. The results showed that α‐Fe2O3 was produced and incorporated across the membranes. A reduction in flux was recorded with the deposition of α‐Fe2O3. However, it improved the adsorption capacity for heavy metal adsorption. The adsorption‐separation test demonstrated that the optimized membrane is able to completely remove Pb(II) ions after two hours. 相似文献
70.
高功率激光器无源器件制作过程中封装不当引入的应力,会导致信号光光束质量劣化和光纤温升,为了解决此问题,理论分析了光纤形变对信号光模式分布的影响,利用有限元方法建立包层光导致光纤发热模型,实验研究了不同封装方式对光纤发热情况和信号光光束质量的影响。实验表明,应力导致的光纤形变会造成信号光M2值在受力方向上略微变小而其垂直方向上变大,在输出100 W信号光时,施加应力导致的M2值的变化最高为0.39,与仿真结果相符。在光纤温升方面,相比于使用硬质胶水带来的12 ℃温升,使用硅橡胶封装的剥离器将温升控制在5 ℃以内,且其封装应力引入的M2值的变化在0.05以内。 相似文献