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1.
A series of polystyrene/glass beads composites were studied by using dynamic mechanical spectrometry. From experimental data obtained under isothermal conditions, a simulation method of viscoelastic behaviour of amorphous thermoplastics reinforced by glass beads was devised. Such a theoretical approach confirmed the requirement of considering the Poisson's ratio as a complex component over all the temperature range. This could be related to the difference of many powers of ten between the moduli of the two phases. Thus, we suggest in this paper a method to evaluate the complex Poisson's ratio of the matrix. From these results, the influence of filler content on the magnitude of the mechanical relaxation related to the glass transition is taken into account. 相似文献
2.
Didier Perrin Céline Guillermain Anne Bergeret José-Marie Lopez-Cuesta Gilles Tersac 《Journal of Materials Science》2006,41(12):3593-3602
A new process of management of waste of composite materials from Sheet Moulding Compounds (SMC), as reinforcing fillers for
thermoplastic materials, including both mechanical and chemical processes is proposed in this paper. Communited SMC being
composed of coated glass fibres intimately mixed with calcium carbonate powder, their reinforcing power is low. First, the
fibrous part was increased by partial dissolution of calcium carbonate present in the crushed products SMC. Second, a process
of partial solvolysis was developed aiming at strong increasing the interfacial mechanical properties by functionalising of
SMC load incorporated into polypropylene/grafted maleic anhydride polypropylene (PP/PPgma). At this effect, we investigated a treatment with a hot triamine (diethylenetriamine, DETA) in order to create a functionalisation,
after scission of the bond ester of unsaturated polyester, as bridging amino-succinimide.The effect of this recycling way
by partial solvolysis was checked from the mechanical properties of the resulting reinforced PP/PPgma material: Although a lower of Young modulus, better yield stress and especially resilience were observed. 相似文献
3.
B. Phung Ngoc C. Geantet J. A. Dalmon M. Aouine G. Bergeret P. Delichere S. Raffy S. Marlin 《Catalysis Letters》2009,131(1-2):59-69
The quasicrystalline structures of alloys with nominal compositions of Al72Ni13.4Co14.6 and Al72.3Ni7.8Co19.8 were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. For catalytic application, the solids were leached with an alkaline NaOH solution and tested at 373 K with two model reactions under atmospheric pressure: hydrogenation of crotonaldehyde and acetonitrile. The catalytic activities of these leached alloys were compared to that of a Raney nickel reference catalyst. Catalysts prepared from quasicrystals showed high catalytic activities and high selectivities towards butanal (in crotonaldehyde hydrogenation) and ethylamine (in acetonitrile hydrogenation). 相似文献
4.
A. S. Vasenko A. Ozaeta S. Kawabata F. W. J. Hekking F. S. Bergeret 《Journal of Superconductivity and Novel Magnetism》2013,26(5):1951-1956
The Andreev current and the subgap conductance in a superconductor/insulator/ferromagnet (SIF) structure in the presence of a small spin-splitting field show novel interesting features (Ozaeta et al. in Phys. Rev. B 86:060509(R), 2012). For example, the Andreev current at zero temperature can be enhanced by a spin-splitting field h, smaller than the superconducting gap Δ, as has been recently reported by the authors. Also at finite temperatures, the Andreev current has a peak for values of the spin-splitting field close to the superconducting gap, h≈Δ. Finally, the differential subgap conductance at low temperatures shows a peak at the bias voltage eV=h. In this paper, we investigate the Andreev current and the subgap conductance in SFF structures with arbitrary direction of magnetization of the F layers. We show that all the aforementioned features occur now at the value of the “effective field”, which is the field acting on the Cooper pairs in the multi-domain ferromagnetic region, averaged over the decay length of the superconducting condensate into a ferromagnet. We also briefly discuss the heat transport and electron cooling in the considered structures. 相似文献
5.
6.
La2CrO6 (Cr6), LaCrO3 (Cr3), LaCrO3–La2CrO6 (Cr6–Cr3) and LaCrO3–La2O3 (Cr3-L) catalysts were synthesised and investigated with in situ X-ray diffraction (ISXRD) during methane catalytic combustion in order to characterise the solid phases present under reactants and to determine the effect of chromium oxidation state on the catalytic activity. Methane conversion was evaluated over a temperature range of 300–800 °C, using oxygen-to-methane ratio of 4 and GHSV of 8,000 h?1. The TPR provided information about the oxygen depletion temperatures characteristic of lattice oxygen mobility in the samples and ISXRD results evidenced a cooperative effect of Cr3 and Cr6 phases at low temperatures (<725 °C) and of Cr3 and LaCrO4 (Cr4) phases at high temperatures (>750 °C). The relative phase composition determined the oxygen activation capability and hence the corresponding activity for the oxidation of methane. It was observed that while direct and back Cr6 ? Cr4 transition temperatures were unaffected by Cr6 content in the samples, the methane conversion was strongly modified. This suggests that Cr3+/Cr6+ and Cr3+/Cr5+ species involved substantial modification of the surface chemistry which affected the catalytic activity. These results provide the first direct evidence of the presence of Cr4 metastable phase during methane combustion over La–Cr–O catalysts. 相似文献
7.
Catalytic hydrodechlorination of hexachlorobenzene on carbon supported Pd-Ni bimetallic catalysts 总被引:4,自引:0,他引:4
V. Simagina V. Likholobov G. Bergeret M. T. Gimenez A. Renouprez 《Applied catalysis. B, Environmental》2003,40(4):293-304
The study of the catalytic activity of carbon supported Pd-Ni catalysts for the hydrodechlorination of hexachlorobenzene was carried out in the liquid phase. The degree of dechlorination was found proportional to the surface Pd concentration, which is enhanced by the segregation of this element at the surface of the bimetallic particles.
It is also shown that isolated Pd atoms located at the surface of Ni rich bimetallic particles are more active than those lying in larger ensembles.
Finally bimetallic Pd-Ni catalysts containing only between 20 and 50 Pd atom%, although less active than pure Pd, lead to 75% of useful compounds, i.e. benzene, mono and dichlorobenzene. 相似文献
8.
J Raymond N Kalach M Bergeret JP Barbet PH Benhamou D Gendrel C Dupont 《Canadian Metallurgical Quarterly》1996,15(5):415-417
A serological test for the diagnosis of Helicobacter pylori infection (Cobas Core Roche, IgG, 2nd Generation; Roche, France) was compared with the examination of biopsy samples (culture and histology) obtained after endoscopy in 115 children to assess its value. In 94 children (42 positive and 52 negative), results were concordant. In 10 children a positive serological test was associated with an absence of Helicobacter pylori, while in 11 others a negative serological test was associated with a positive culture. Sensitivity of the test was 79.2% and specificity 83.9%. A relationship between IgG titers and age (r = 0.31, p < 0.05) was found. Serological tests could be useful for the diagnosis of Helicobacter pylori infection, but a negative test result does not rule out infection, particularly in children under 10 years of age. 相似文献
9.
The majority of minerals present in natural rubber are associated with the macrogel: An ICP‐MS and SEM/EDX investigation 下载免费PDF全文
Sébastien Rolere Christine Char Jean Marie Taulemesse Anne Bergeret Jérôme Sainte‐Beuve Frédéric Bonfils 《应用聚合物科学杂志》2016,133(9)
The mineral composition of the insoluble (macrogel) and soluble fractions of two natural rubber (NR) samples made from the latex of two different clones (RRIM600 from Thailand and GT1 from Côte d'Ivoire) was determined using inductively coupled plasma mass spectrometry (ICP‐MS). The ICP‐MS results showed that mineral elements were concentrated in the macrogel. The major mineral elements found in macrogel were phosphorus, magnesium, potassium, and sulfur. Some mineral elements were mostly concentrated in micron‐sized mineral aggregates, visible at the surface of the samples using scanning electron microscopy coupled with an energy dispersive X‐ray microanalyzer (SEM/EDX). The nature of these mineral aggregates was found to be highly variable. Their inhomogeneous distribution in the macrogel indicates that these aggregates do not have a major influence on macrogel structure. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43062. 相似文献
10.
Molecular mobility of both the polystyrene homopolymer and a series of styrene-co-meth-acrylic acid copolymers with various amounts of methacrylic acid is analyzed in the tem-perature range from 100 to 450 K, by high-resolution dynamic mechanical spectrometry, IR, and differential scanning calorimetry. Isochronal spectrometry exhibits for polystyrene homopolymer two relaxations, the β and α relaxations, with increasing temperature. Styrene-co-methacrylic acid copolymers exhibit three mechanical relaxations, the γ, β, and α re-laxations, from 100 to 450 K. These relaxations could be related to the progressive occurring of motions of the side groups and of the backbone chains when increasing the temperature. This could be due to the progressive breakdown of hydrogen bonds, which could show a somewhat wide range of magnitude. Furthermore, The decreasing of the magnitude of the α relaxation with increasing methacrylic acid content could suggest the presence of a stable network of chemical cross-links induced by the presence of anydride so that molecular mobility could be partially inhibited above Tg. The remaining of a fluctuation network of hydrogen bonds (labile contacts) above Tg could also emphasize the decrease in molecular mobility. © 1993 John Wiley & Sons, Inc. 相似文献