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81.
New nanocomposite materials based on polyurethane intercalated into organoclay layers have been synthesized via in situ polymerization. The syntheses of polyurethane–organoclay hybrid films were carried out by swelling the organoclay [12‐aminododecanoic acid montmorillonite] into different kinds of diols followed by addition of diisocyanate then casting in a film. The homogeneous dispersion of MMT in the polymer matrix is evidenced by scanning electron microscope and x‐ray diffraction, which showed the disappearance of the peak characteristic to d001 spacing. It was found that the presence of organoclay has improved the thermal, solvent resistance and mechanical properties. Also, the tensile strength is increased with increasing the organoclay contents to 20% by the ratio 182% related to the PU with 0% organoclay. On the contrary, the elongation has decreased with increasing the organoclay contents. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
82.
B. Orel U. Opara Krašovec U. Lavrenčič Štangar P. Judeinstein 《Journal of Sol-Gel Science and Technology》1998,11(1):87-104
This paper reports on the development of all sol-gel EC devices, having the configuration WO3/ormolyte/SnO2:Mo, WO3/ormolyte/SnO2:Sb and WO3/ormolyte/SnO2:Sb:Mo, where all three internal layers, including the ionically conductive inorganic-organic hybrid (ormolyte), are prepared via the sol-gel route. The electrochemical and optical properties of EC devices are presented and their cycling stability and reversibility of their optical modulation assessed. The transmission modulation of the devices depends on the thickness of the active electrochromic, counter-electrode and ormolyte layer. The electrochemical and optical properties of individual films and the structural properties of the ormolyte are described and correlated with the stability of the all sol-gel EC devices. 相似文献
83.
Elena?Fabbri Paola?Fabbri Massimo?MessoriEmail author Monica?Montecchi Francesco?Pilati Stefano?Nannarone Luca?Pasquali Maurizio?Toselli Claudio?Tonelli 《Journal of Sol-Gel Science and Technology》2005,34(2):155-163
,-Triethoxysilane terminated perfluoropolyether-polycaprolactone block copolymers, TXCL(x)Si, were synthesised, characterised and subsequently reacted with tetraethoxysilane to prepare transparent organic-inorganic hybrid materials by using the sol–gel process. Surface characterization was carried out through contact angle measurements. All the materials investigated (independently on both the reaction time of the sol–gel reaction before coating application and the bulk organic-inorganic ratio) showed a strong hydrophobic character when compared with non-fluorinated and fully inorganic control materials. The highest water contact angles were obtained when TXCL(x)Si oligomer used for the preparation of the hybrid contained short hydrogenated polycaprolactone segments. In all cases, the surface tension values indicated that the very surface at the air-coating interface showed almost completely perfluoropolyether segments. 相似文献
84.
Ahmet Nebioglu 《European Polymer Journal》2007,43(8):3325-3336
Polyester acrylate inorganic/organic hybrids were prepared using a sol-gel precursor, coupling agent, and reactive diluent. The hybrids were cured via a UV-free radical initiator. Design of experiments (DOE) was utilized to investigate reaction kinetics and complex variable interactions. The effects of the silicate groups on the free radical photo-curing reaction kinetics were investigated utilizing a time-resolved Fourier transform infrared (FT-IR) spectroscopy and a differential scanning calorimeter equipped with a photocalorimetric accessory (photo-DSC). Microgel and inorganic network formation during the UV-initiated free radical crosslinking reactions was suggested to describe the complex gel-point behavior. It was proposed that the formation of the inorganic silicate groups retarded the organic crosslinking reactions. The UV-cured inorganic/organic hybrid films exhibited more homogeneous film morphology compared to the organic counterparts. In the hybrid films, a core-shell like inorganic/organic particle morphology was observed. The UV-crosslinked organic phase forms the core, whereas, the inorganic silicate forms the surrounding shell. 相似文献
85.
Bruno A. Latella Michel Ignat Christophe J. Barbé David J. Cassidy John R. Bartlett 《Journal of Sol-Gel Science and Technology》2003,26(1-3):765-770
The mechanical properties of organically modified silicate coatings on stainless steel substrates were investigated, using nano-indentation and simultaneous in situ microtensile testing/optical microscopy. The load-displacement response and fracture behaviour is examined to ascertain the effects of different organic groups on the film properties and adhesion characteristics. The relationship between the morphology and mechanical properties of the films is discussed, and it is demonstrated that the mechanical response of the coatings is significantly influenced by the nature of the organic group attached to the ormocer precursor. 相似文献
86.
Kenneth G. Sharp Michael J. Michalczyk 《Journal of Sol-Gel Science and Technology》1997,8(1-3):541-546
New molecular precursors to inorganic/organic hybrid network materials have been designed and synthesized. The molecules comprise multiple trialkoxysilane-terminated arms linked to an organic core. When hydrolyzed, these materials form network structures whose network elements are interconnected with flexible crosslinks. Clear, compliant glasses and thick films have been generated from a number of these precursors. They are significantly tougher and less brittle than purely inorganic glasses or conventional purely organic thermosetting materials such as epoxy resins. The gels typically lose all surface-connected porosity during drying. Gelation rates for pure star gel precursors can be extremely high; the stars can also greatly enhance condensation rates for conventional sol-gel systems based on tetraalkoxysilanes. 相似文献
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In previous work (Krasnogor, . In: Studies on the Theory and Design Space of Memetic Algorithms. Ph.D. thesis, University of the West of England, Bristol,
UK, 2002; Krasnogor and Smith, IEEE Trans Evol Algorithms 9(6):474–488, 2005) we develop a syntax-only classification of evolutionary algorithms, in particular so-called memetic algorithms (MAs). When
“syntactic sugar” is added to our model, we are able to investigate the polynomial local search (PLS) complexity of memetic
algorithms. In this paper we show the PLS-completeness of whole classes of problems that occur when memetic algorithms are
applied to the travelling salesman problem using a range of mutation, crossover and local search operators. Our PLS-completeness
results shed light on the worst case behaviour that can be expected of a memetic algorithm under these circumstances. Moreover,
we point out in this paper that memetic algorithms for graph partitioning and maximum network flow (both with important practical
applications) also give rise to PLS-complete problems.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献