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121.
Guan Gong Wei Yang Mingbo Yang Jingshen Wu 《Journal of Macromolecular Science: Physics》2013,52(5):870-885
The role of spherical nano-CaCO3 particles treated with 2 wt% and 6 wt% stearic acid (SA), respectively, on the motion of macromolecular chains and segments of isotactic polypropylene (iPP) was studied through the dynamic mechanical analysis and nonisothermal crystallization. Higher nucleation activity of the particles and more nucleating sites were achieved in the 6 wt% SA treated particle nanocomposites with respect to the 2 wt% SA counterpart. The increased nucleation efficiency caused high inhomogeneity and thus large mobility of the amorphous phase of iPP, which favored a low glass transition temperature (Tg ) in the nanocomposites. However, the spherical nanoparicles also spatially restrained the motion of macromolecular chains and segments, and the better the nanoparticles dispersed, the stronger the restriction was. Thus the glass transition temperature (Tg ) of the nanocomposites decreased with increasing filler loading but recovered at a certain particle concentration. At this filler content, the maximal α-transition temperature (Tα ) and the main melting peak temperature (Tm1 ) as well as the lowest degree of crystallinity (XPP ) also occurred. This critical filler loading appeared at lower value (20 wt%) in 6 wt% SA treated nano-CaCO3 composites with respect to 2 wt% SA counterpart (25%) due to the better dispersion of particles in the former. It was concluded that the mobility of the macromolecular chains and segments of iPP was dominated by the competition of the spatial confinement and nucleation effect of nano-CaCO3 particles in the matrix. 相似文献
122.
Diameter dependence of hybrid shish‐kebab structure in polyethylene/carbon material fiber composites
Xiaochao Xia Xi Zhang Dandan Xie Yanhao Huang Youbing Li Mingbo Yang 《Journal of Polymer Science.Polymer Physics》2019,57(6):297-303
PE chains can proceed template crystal growth on multi‐walled carbon nanotubes (MWCNTs) surface and develop into hybrid shish‐kebab (HSK) abiding by the “soft epitaxy” mechanism. For large‐diameter carbon nanofiber (CNF), the lattice matching and epitaxy are the main mechanism for hybrid structure formation under the static state. This study provided a new understanding of HSK formation, wherein PE underlay on the surface of carbon material fiber played an important role. The shear flow induced PE chains to orient along the CNF surface and formed PE underlayer. Subsequently, ordered subglobules were periodically formed along the CNF axis and finally evolved to typical HSK structures with well‐aligned arraying PE lamellae rather than random one. As the diameter increased to 7000 nm, even though the graphite (002) planes in carbon fibers (CFs) was similar to that in CNFs, the attractive van der Waals interactions between CFs and PE chains were too weak to drive enough PE chains to absorb on the CFs surface and form PE underlay even under the shear flow, leading to the absence of PE lamellae on the CF surface. Based on that, the “soft epitaxy” could be the main formation mechanism of HSK structures for carbon material fibers regardless of their diameters. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 297–303 相似文献
123.
Xin Sun Guanghao Shen Hongwang Shen Banghu Xie Wei Yang Mingbo Yang 《Journal of Macromolecular Science: Physics》2013,52(10):1372-1387
Two kinds of polyethylenes, high-density polyethylene (HDPE) with few chain branches and short-chain branched linear low-density polyethylene (LLDPE) with a relatively larger average molecular weight, were melt blended together in various mass ratios based on consideration of their practical applications. After identifying the good compatibility of the blends, their crystallization behaviors were studied by the successive self-nucleation and annealing (SSA) technique. The SSA analysis showed that not merely the number of melting fractions in the SSA curves changed with the blend composition, but also the content of the first two melting fractions at high temperature of SSA curves showed a positive deviation and a negative deviation with the blend composition, respectively. These phenomena, as well as the interesting appearance of a stepped increase of the lamellar thickness of each fraction with the highest temperature in each sample, indicated that co-crystallization occurred between HDPE and LLDPE. The results from wide-angle X-ray diffraction (WAXD) supported the conjecture obtained by the SSA analysis. 相似文献
124.
Hierarchically Porous NaCoPO4–Co3O4 Hollow Microspheres for Flexible Asymmetric Solid‐State Supercapacitors 下载免费PDF全文
Chengzhen Wei Cheng Cheng Binbin Zhou Xin Yuan Tingting Cui Shanshan Wang Mingbo Zheng Huan Pang 《Particle & Particle Systems Characterization》2015,32(8):831-839
A template‐free hydrothermal method is developed to prepare hierarchical hollow precursors. An inside‐out Ostwald ripening mechanism is proposed to explain the formation of the hollow structure. After the calcination in the air, hierarchically meso/macroporous NaCoPO4–Co3O4 hollow microspheres can easily be obtained. When being evaluated as electrode materials for a supercapacitor, the hierarchically porous NaCoPO4–Co3O4 hollow microspheres electrode shows a specific capacitance of 268 F g?1 at 0.8 A g?1 and offers a good cycle life. More importantly, the obtained materials are successfully applied to fabricate flexible solid‐state asymmetric supercapacitors. The device exhibits a specific capacitance of 28.6 mF cm?2 at 0.1 mA cm?2, a good cycling stability with only 5.5% loss of capacitance after 5000 cycles, and good mechanical flexibility under different bending angles, which confirms that the hierarchically porous NaCoPO4–Co3O4 hollow microspheres are promising active materials for the flexible supercapacitor. 相似文献
125.
Yuanying Liu Huan Pang Chengzhen Wei Mingming Hao Shasha Zheng Mingbo Zheng 《Mikrochimica acta》2014,181(13-14):1581-1589
Mesoporous ZnO-NiO architectures were prepared by thermal annealing of zinc-nickel hydroxycarbonate composites. The resulting architectures are shown to be assembled by many mesoporous nanosheets, and this results in a large surface area and a strong synergy between the ZnO and NiO nanoparticles. The material obtained by annealing at 400 °C was used as an electrode that responds to glucose over a wide concentration range (from 0.5 μM to 6.4 mM), with a detection limit as low as 0.5 μM, fast response time (<3 s), and good sensitivity (120.5 μA?·?mM?1?·?cm?2). Figure
The mesoporous ZnO-NiO architecture by annealing at 400 °C was used as an electrode that responds to glucose over a wide concentration range (from 0.5 μM to 6.4 mM), with a detection limit as low as 0.5 μM, fast response time (<3 s), and good sensitivity (120.5 μA?·?mM?1?·?cm?2 相似文献