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131.
The effects of different
cationic surfactants (n-undecylammonum chloride, UDACl and dodecyldimethyl
(dodecyloxymethyl) ammonium chloride, DDMDDACl) on fully hydrated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) vesicles have
been studied. In the studied systems the molar ratio (x)
of DPPC/surfactant ranged between x=0.0164–0.82
and from x=0.0352–1.76 for DPPC/DDMDDACl
and DPPC/UDACl, respectively. For both systems, the enthalpy associated with
the phase transition significantly decreases even at the lowest surfactant
concentration. Also the main phase transition temperature is shifted towards
lower temperatures.
The structural parameters of the phases have
been characterised by small angle X-ray scattering (SAXS). The SAXS results
have proved that UDACl at x=0.0352 molar
ratio significantly influences the DPPC lamellar structure, while its total
disappearance was observed for x=0.176.
The presence of DDMDDACl causes a total disappearance of the DPPC lamellar
structure already at the lowest molar ratio (x=0.0352).
Each surfactant in the system with DDPPC leads to a mixed micellar phase formation. 相似文献
132.
聚乙烯片晶辐照破坏的X射线散射研究 总被引:2,自引:0,他引:2
聚乙烯片晶辐照破坏的X射线散射研究王国英,姜炳政(中国科学院长春应用化学研究所长春130022)关键词辐照聚乙烯,广角X射线衍射,小角X射线散射有关聚乙烯辐照破坏和交联问题,Hoseman等[1]从X射线衍射的研究指出,辐照交联和破坏在晶区内部发生;... 相似文献
133.
A. J. Ryan 《Journal of Thermal Analysis and Calorimetry》1993,40(3):887-899
The simultaneous SAXS/WAXD technique is shown to provide an unambiguous method for following structural changes taking place
during the programmed heating of a range of multiphase polymeric materials. Results are given for polyethylene, block copolyurethanes
and block copolyesters containing liquid crystalline hard segments.
UK Thermal methods Group Award Lecture 相似文献
134.
Steve Granick Sanat K. Kumar Eric J. Amis Markus Antonietti Anna C. Balazs Arup K. Chakraborty Gary S. Grest Craig Hawker Paul Janmey Edward J. Kramer Ralph Nuzzo Thomas P. Russell Cyrus R. Safinya 《Journal of Polymer Science.Polymer Physics》2003,41(22):2755-2793
A comprehensive review of ongoing and recommended research directions concerning the structure, dynamics, and interfacial activity of synthetic and naturally occurring macromolecules at the solid–liquid interface is presented. Many new developments stem from the ability to target new size regimes of 1–100 nm. These rapid developments are reviewed critically with respect to chemical synthesis, processing, structural characterization, dynamic processes, and theoretical and computational analysis. The common problems shared by flat and particulate surfaces are emphasized. A broad spectrum of material properties are discussed, from the control of interfacial friction between surfaces in moving contact, to the mechanical strength and durability of the interfaces in hybrid materials, to optical and electronic properties. Future research opportunities are identified that involve (1) the emergence of nanoscale material properties, (2) polymer‐assisted nanostructures, and (3) the crossroads between interfacial science and biological and bioinspired applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2755–2793, 2003 相似文献
135.
Milagrosa Ramirez del Solar Luis Esquivias 《Journal of Sol-Gel Science and Technology》1994,3(1):41-46
A first approach to the ultrastructural evolution during the sintering process of TiO2-SiO2 aerogels has been done on the basis of the gelation kinetics and dried gel previous analysis, in order to tailor the mixed glass sol-gel processing.Small Angle X-Ray Scattering (SAXS) technique was used to study the evolution of the ultrastructure of porous aerogels partially densified at several temperatures. The analysis of the scattering intensity profiles on the basis of the Porod's Two Phase Media Model gives valuable information about pore-solid matrix interface evolution on sintering. 相似文献
136.
Göttlicher J. Pentinghaus H.J. Himmel B. 《Journal of Sol-Gel Science and Technology》1998,13(1-3):85-88
The submicron structures of two natural hydrous forms of silica (geyserites from Iceland, hyalite from Valec CS) have been studied by scanning electron microscopy, small-angle and wide-angle X-ray scattering. All geyserites investigated are particulate with a nonuniform size distribution. These particles are arranged in spherical agglomerates, in chains or in helical patterns. The average diameters of the colloidal particles range between 200 nm and 2 m depending on the texture of the samples. SAXS experiments have revealed the porous nature of the particles with inhomogeneities smaller than 10 nm. Based on the structural pecularities of the geyserites their origin is discussed as the result of forced condensation of silicic acid in an aqueous environment, particle agglomeration and sedimentation. The structural development including the textures is determined by the dynamics of the underlying processes: fast decompression and cooling of the saturated parent solutions and their transport. By contrast, hyalite is characterized by a homogeneous microstructure. 相似文献
137.
Flexible transparent fluorinated nanohybrid with innovative heat‐resistance property—new technology proposal for fabrication of transparent materials using “crystalline” polymer
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Muhammad Abdullah Al Mamun Youichi Soutome Qi Meng Atsuhiro Fujimori 《Journal of Polymer Science.Polymer Physics》2015,53(23):1674-1690
A new technology for the production of transparent material, using a “crystalline” polymer, is proposed in this study. In addition, a heat‐resistant transparent flexible plastic film with a high hydrophobic surface and a thermal decomposition temperature near 400 °C was created. Partially fluorinated crystalline polymer with switchboard‐type lamellae results high transparency as a consequence of the formation of a high‐density amorphous structure based on high‐temperature drawing just below the melting point at 250 °C. Melt‐compounding with montmorillonite modified by the long‐chain quaternary phosphonium with high coverage induces formation of a nanohybrid that retains transparency and also results in an increase in the thermal degradation temperature by over 50 °C. Through this technology, which results in heat‐resistance, transparency, and flexibility, the nano‐micro‐millimeter structures of solid‐state polymers are hierarchically controlled, which enables the creation of new materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1674–1690 相似文献
138.
Crystallization and melting of isotactic polypropylene crystallized from quiescent melt and stress‐induced localized melt
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Ying Lu Yaotao Wang Ran Chen Yongfeng Men 《Journal of Polymer Science.Polymer Physics》2017,55(12):957-963
Temperature dependency of crystalline lamellar thickness during crystallization and subsequent melting in isotactic polypropylene crystallized from both quiescent molten state and stress‐induced localized melt was investigated using small angle X‐ray scattering technique. Both cases yield well‐defined crystallization lines where inverse lamellar thickness is linearly dependent on crystallization temperature with the stretching‐induced crystallization line shifted slightly to smaller thickness direction than the isothermal crystallization one indicating both crystallization processes being mediated a mesomorphic phase. However, crystallites obtained via different routes (quiescent melt or stress‐induced localized melt) show different melting behaviors. The one from isothermal crystallization melted directly without significant changing in lamellar thickness yielding well‐defined melting line whereas stress‐induced crystallites followed a recrystallization line. Such results can be associated with the different extent of stabilization of crystallites obtained through different crystallization routes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 957–963 相似文献
139.
140.
W. Salgueiro A. Somoza I. L. Torriani A. J. Marzocca 《Journal of Polymer Science.Polymer Physics》2007,45(21):2966-2971
To analyze the natural rubber behavior during vulcanization under different cure treatments, an experimental investigation using small angle X‐ray scattering was performed. To achieve this, a set of samples were prepared using sulfur and N‐t‐butyl‐2‐benzothiazole sulfenamide as accelerator and then cured at temperatures between 403 and 463 K reaching their optimum mechanical properties considering rheometer tests. The crosslink density of the samples was evaluated by means of the swelling technique in solvent. In the usual Lorentz corrected representation of the X‐ray scattered intensity, a maximum was observed in the plots corresponding to the cured samples, revealing a highly correlated structure. This maximum shifted toward higher values of the scattering vector when the cure temperature of the samples increased. This behavior is discussed in terms of the crosslinks type present in the vulcanized rubber network at different cure temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2966–2971, 2007 相似文献