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991.
Poly(vinylidene fluoride) (PVDF) based nanocomposites with different surface-functionalized multi-walled carbon nanotubes (MWCNTs) were prepared by melt mixing in a small scale compounder. With the incorporation of commercial functionalized MWCNTs, the β-phase in PVDF can be directly achieved from melt cooling, as verified by results of Fourier transform infrared spectrum and X-ray diffraction. Interestingly, nanocomposites with amino group functionalized MWCNTs showed the highest percentage of β-phase (17.4%) formation in PVDF, followed by those with hydroxyl groups (11.6%) and unmodified MWCNTs (9.4%). However, the nanocomposites containing MWCNTs with carboxyl groups which were thought to be able to well interact with the dipoles on PVDF chains have the lowest amount of β-phase, i.e. 4.7%. The analysis on the mechanism of the influence of surface functionalization of MWCNTs on the formation of β-phase in PVDF shows that the combined effects of the dispersion of MWCNTs and the nanotube–polymer interactions account for the formation of the β-phase in PVDF. 相似文献
992.
Shouwen Shi Dan Liu Dazhi Liu Patrick Tae Carrie Y. Gao Lei Yan Ke An Xu Chen 《Polymer Engineering and Science》2014,54(10):2215-2221
In this study, mechanical tensile stress–strain response and microstructure changes of proton exchange membranes (PEM) in immersed conditions are studied. The effects of water pretreatment and immersion time on stress–strain responses of Nafion®?212 membranes are discussed. It is found that in the water immersion it took 24 h for the membrane to reach saturation equilibrium. Compared with dry membrane, immersed Nafion membrane shows a lower stress level at 30°C, but a higher stress level at 70°C. In situ small angle neutron scattering (SANS) experiments show that with the increase of temperature and water uptake, domains of the membrane become ordered and stay stable at around 60°C. Based on the observation, the relationship between the microstructure and mechanical properties is explained. POLYM. ENG. SCI. 54:2215–2221, 2014. © 2013 Society of Plastics Engineers 相似文献
993.
采用原位聚合法分别在玻璃鳞片和绢云母表面负载聚苯胺,合成了玻璃鳞片聚苯胺复合材料(简称PANI-glass)和云母粉聚苯胺复合材料(简称PANI-sericite);利用红外光谱、场发射扫描电镜、热失质量分析和X射线衍射等手段对复合材料表面特性进行表征,结果显示2种颜料表面均吸附有纳米聚苯胺,玻璃鳞片极性表面负载更多聚苯胺;同时考察了复合材料在改性环氧涂料中的防腐蚀行为,电化学数据和盐雾测试结果显示,PANI-glass提高了环氧涂层的屏蔽效应和防腐性能。 相似文献
994.
995.
Single phase multiferroic BiFeO3 (BFO) ceramics were synthesized with controllable amount of Fe2+ and oxygen vacancies in a very wide concentration range. Double ferroelectric hysteresis loops are observed in fresh BFO ceramics at room temperature without any aging processes. Detailed study shows that this is due to the defect dipoles which have preferential orientations antiparallel to the direction of spontaneous polarization, providing a driving force for domain back-switching. The dielectric constant of BFO could be enormously enhanced by 100 times by increasing the Fe2+ content, employing a polaronic relaxation process. 相似文献
996.
There are growing evidences that Sr-containing calcium phosphate biomaterials can promote better osteo-precursor cell attachment and proliferation than pure calcium phosphate biomaterials. In this study, attempts were made to fabricate two kinds of Sr-substituted calcium phosphate (Ca–Sr–P) coatings on pure magnesium in electrolyte solutions with differing amounts of Sr(NO3)2 for biomedical application. The surface microstructure, composition and chemistry of the coatings were characterized by Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDS), and X-ray Diffractometer (XRD), respectively. In addition, electrochemical and immersion tests were performed to evaluate the corrosion resistance of the Ca–Sr–P coated magnesium in phosphate buffered saline solution (PBS). 相似文献
997.
Jia-Jun Zhou Li-Qian Cheng Ke Wang Xiao-Wen Zhang Jing-Feng Li Hong Liu Jing-Zhong Fang 《Ceramics International》2014
0.25 wt% CuO-doped (Li,K,Na)(Nb,Ta)O3–AgSbO3 lead-free piezoceramics with pure perovskite structure were successfully prepared at a sintering temperature below 1000 °C. The sintering temperature of KNN-based piezoceramics was effectively reduced by about 100 °C due to the enhanced densification process induced by the addition of CuO. Besides, the acceptable sintering temperature window was broadened by the addition of CuO. It is found that the CuO-doped samples show slightly higher tetragonal–orthorhombic phase transition point (TT−O) but a lower Curie point (Tc), compared to undoped ones. The KNN-based piezoceramics became “hard” as CuO was added, supported by an increase of Qm. Fairly good electrical properties of d33*=383 pm/V, εr=860, Qm=188 and Tc=215 °C could be obtained in dense CuO-modified KNN-based piezoceramics sintered at 970 °C, demonstrating promising potential in practical applications. 相似文献
998.
建立了同时测定化妆品中铬、锰、镍、铜、锌、砷、硒、镉、锑、锡、汞和铅12种元素含量的测定方法。样品经微波消解,采用电感耦合等离子体质谱法(ICP-MS)同时测定12种元素。结果表明,12种元素线性关系良好(r=0.999 6~1.000 0),方法检出限为0.04~0.43 mg·kg-1,重复性实验的相对标准偏差为1.17%~9.69%,回收率为82.9%~115.1%。该方法简便快速、准确性高、可靠性强,可较好的应用于化妆品的元素测定。 相似文献
999.
1000.
文章介绍了两种国产聚丙烯催化剂在神华宁夏煤业集团烯烃公司50万吨/年聚丙烯装置上的应用情况。通过试用,两种国产催化剂对反应器的温度影响较小,PG催化剂活性、三剂消耗量与进口催化剂一致;BCND-II催化剂与进口催化剂相比,活性较低,氢调敏感性相对要差,在今后的应用过程中,需要催化剂厂家进行相应的调整。 相似文献