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纳米白炭黑对NBR性能的影响 总被引:1,自引:0,他引:1
试验研究表面改性剂品种及其用量、纳米白炭黑粒径及其用量以及纳米白炭黑/炭黑并用比对NBR硫化胶物理性能的影响。结果表明,表面改性剂对纳米白炭黑填充NBR硫化胶物理性能的影响程度大小顺序为硅烷偶联剂KH-550、钛酸酯偶联剂NDZ-201、表面活性剂ABS。用0.6份硅烷偶联剂KH~550对纳米白炭黑进行改性后,当纳米白炭黑粒径为5~15nm(用量为30份);纳米白炭黑用量为50份(粒径为15~25nm);纳米白炭黑/炭黑并用比为15/35(纳米白炭黑粒径为15~25nm)时,NBR硫化胶的综合物理性能最佳。 相似文献
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将硅烷偶联剂KH-550改性以及硅烷偶联剂KH-550和K-MEPTS共同改性的白炭黑与氧化石墨烯(GO)复配补强天然橡胶(NR),研究填料与橡胶基体的界面结合方式对胶料性能的影响。结果表明:由硅烷偶联剂KH-550和K-MEPTS共同改性的白炭黑与GO静电组装制得的改性白炭黑-2/GO填充NR得到的胶料具有低的Panye效应和高的结合胶含量,这表明改性白炭黑-2/GO在橡胶基体中的分散性好且与橡胶基体通过共价连接结合紧密;改性白炭黑-2/GO/NR硫化胶滞后损失小,具有低的压缩疲劳温升和高的拉伸强度。 相似文献
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Chan Joong Kim Suk-Joong L. Kang Dong-Yeon Won 《Journal of the American Ceramic Society》1992,75(3):570-574
Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed. 相似文献
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BxCyNz nanoscale materials, hybrids of h-BN and graphite, have been recently synthesised using various techniques. Here, we present the latest advances in the synthesis and characterisation of B-C-N nanotubes and nanofibres. In particular, we focus on layered BC2N, BN, BC and CNx systems, reviewing their production methods as well as their structural and electronic properties. These materials may find important applications in the fabrication of nanotransistors, robust nanocomposites, conducting polymers, storage components and field emission sources. 相似文献
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The crystal structure of lanthanum-modified lead magnesium niobates having composition (Pb1− x La x ) (Mg(1+ x )/3 -Nb(2− x )/3 )O3 with X = 0 to 1 was investigated by X-ray powder diffraction. It was found that the fundamental reflections from perovskite structure remain in the whole range of composition. The superlattice reflections from the A(B'1/2 -B"1/2 )O3 ordered structure are also well preserved for La content greater than 50 at.%; however, a series of extra peaks of mixing indices appears, with intensities gradually enhanced with the increase of La content. For the complete substitution of Pb by La, a splitting of some reflections can be observed in the diffraction pattern. The results indicate that the crystal structure evolves continuously with the La content, from disordered cubic perovskite of space group Pm 3 m for X = 0, to ordered cubic perovskite of space group Fm 3 m for X = 0.5, distorted cubic perovskite of space group Pa 3 for 0.5 < X < 0.9, and finally to a rhombohedral perovskite, possibly belonging to the space group R 3 , for X ≥ 0.9. In the evolution of structure, a linear reduction of the lattice constant of the perovskite cell from 4.048 to 3.964 Å was observed. 相似文献
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A new ampholytic homopolypeptide, , which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO4 and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu2+ and Ca2+, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu2+ complex near 240 nm. Dependence of the peak intensity on pH at various q values () indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu2+ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu2+ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu2+-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation. 相似文献
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Sergey Kucheiko Dong-Hun Yeo Ji-Won Choi Seok-Jin Yoon Hyun-Jai Kim 《Journal of the American Ceramic Society》2002,85(5):1327-1329
The microwave dielectric properties of CaTi1− x (Al1/2 Nb1/2 ) x O3 solid solutions (0.3 ≤ x ≤ 0.7) have been investigated. The sintered samples had perovskite structures similar to CaTiO3 . The substitution of Ti4+ by Al3+ /Nb5+ improved the quality factor Q of the sintered specimens. A small addition of Li3 NbO4 (about 1 wt%) was found to be very effective for lowering sintering temperature of ceramics from 1450–1500° to 1300°C. The composition with x = 0.5 sintered at 1300°C for 5 h revealed excellent dielectric properties, namely, a dielectric constant (ɛr ) of 48, a Q × f value of 32 100 GHz, and a temperature coefficient of the resonant frequency (τf ) of −2 ppm/K. Li3 NbO4 as a sintering additive had no harmful influence on τf of ceramics. 相似文献
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The structure and temperature dependence of complex lead perovskite dielectrics were investigated for the system (1 − x )Pb(Yb1/2 Ta1/2 )O3 – x Pb(Lu1/2 Nb1/2 )O3 . Superlattice reflections for the compositions 0.8 < x < 1.0 were observed by X-ray diffractometry, and the temperature-composition dielectric-state diagram was determined. In the present study, the disordered middle composition, with 0.2 < x < 0.8, showed a diffuse paraelectric–ferroelectric phase transition, whereas the ordered end compositions, with 0 ≤ x < 0.2 and 0.8 < x ≤ 1.0, revealed successive sharp paraelectric–antiferroelectric and weak antiferroelectric–ferroelectric phase transitions. The dielectric state was confirmed by examining the variation of polarization ( P ) with electric field ( E ). 相似文献