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961.
We have simulated the two- and three-dimensional Ising models at their respective critical points with a conventional Monte Carlo algorithm. From the power spectrum of the magnetization autocorrelations we have determined the dynamic critical exponents and obtained the valuesz = 2.16–2.19 andz = 2.05, in agreement with the results quoted in the literature. We have also studied the power spectrum for the Kardar-Parisi-Zhang and Sun-Guo-Grant equations describing interface dynamics. Arguments similar to what was recently used to conclude thatz = 4 - for model B in critical dynamics were applied to the Sun-Guo-Grant growth model and the known exact values for the roughening and dynamic exponents were obtained. From an analysis of the corresponding power spectrum in self-organized critical sand models one obtains a recently proposed hyperscaling relation. 相似文献
962.
M. B. Urquiola E. D. Sudol V. L. Dimonie M. S. El-Aasser 《Journal of polymer science. Part A, Polymer chemistry》1993,31(6):1403-1415
A mathematical model was developed to aid in the further understanding of the growth of latex particles in the emulsion polymerization of vinyl acctate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40). The model incorporates the main features of the system observed experimentally: copolymerization in the aqueous phase, at the particle surface, and chain transfer to TREM LF-40. The reactions at the particle/water interface and, more specifically, the chain transfer to TREM LF-40 leading to a decrease in the average number of radicals per particle, was found to be the most significant mechanism for explaining the difference in kinetic results found for TREM LF-40 and its nonpolymerizable counterpart. The copolymerization of vinyl acetate with TREM LF-40 was also shown to slow the overall polymerization rate. However, the copolymerization alone was not sufficient to account for the decreased polymerization rates observed experimentally. A combination of copolymerization and chain transfer to TREM LF-40 was found to provide a good fit of the experimental results. © 1993 John Wiley & Sons, Inc. 相似文献
963.
《Surface and interface analysis : SIA》2004,36(7):649-653
Nanoindentation experiments were done on Si3N4/Ni/Si3N4 specimens bonded at different temperatures. Tests were carried out in both the ceramic adherent and the metal filler. Results from nanoindentation experiments done across the interlayer verify that a solution of Si atoms in the Ni interlayer did not modify the mechanical properties of the metal (elastic modulus and hardness). The increase in bonding temperature produced an increase in hardness in the metal interlayer but did not affect its elastic modulus. This hardening of the Ni interlayer was related to the decrease in the shear strength of these joints. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
964.
Drábik M. Gáliková L. Varshney K. G. Quraishi M. A. 《Journal of Thermal Analysis and Calorimetry》2004,76(1):91-96
The applicability of MDF synthesis procedure, the coincidence of the interfacial cross-linking and the moisture resistance
of MDF-related mixes based on two industrial Portland cements (CEM I, CEM II) and poly-P are reported. The knowledge of the
moisture resistance of synthesized material is of paramount importance; two independent experimental methods confirmed that
the moisture resistance of MDF cements based on CEM I (or CEM II) with 5% of poly-P achieves sufficient levels at 50% RH and
at ambient values of RH. The results of thermal analysis are directly related to the former knowledge on the appearance and
role of cross-links in the interfacial zone of MDF cements.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
965.
966.
N. Vila Romeu J. Miñones E. Iribarnegaray O. Conde M. Casas 《Colloid and polymer science》1997,275(6):580-586
The properties of mono layers of poly[(D,L-lactic acid)-co-(glycolic acid)] (PLA/GA) are strongly conditioned by the nature of the solvent from which they are spread. In this work,
we studied the properties of PLA/GA films deposited on water from acetonitrile (a poor spreading solvent) and chloroform (a
good one), observing marked differences with regard to the influence of the pH, temperature and ionic strength of the subphase.
These differences were attributed to the structure of PLA/GA at the air/water interface, being pre-determined by its structure
in the bulk spreading solvent (closely coiled in acetonitrile, unfolded in chloroform). Viscosity measurements on acetonitrile
and chloroform solutions of PLA/GA, and the calculation of the corresponding intermolecular expansion factor, α, confirmed
that PLA/GA was better solvated by chloroform than by acetonitrile, in which intramolecular interactions between polymer segments,
and thus coiling, will therefore have predominated over polymer–solvent interactions.
Received: 14 October 1996 Accepted: 7 January 1997 相似文献
967.
968.
969.
We have used the cell dynamic simulations (CDS) method to study the evolution of asymmetric and symmetric diblock copolymers under electric fields. For symmetric diblock copolymers, long-range-ordered lamellar phases form readily under electric fields. For asymmetric diblock copolymers, sphere-to-cylinder phase transitions occur rapidly when strong electric fields are applied, but it takes longer for the system to form hexagonal cylinder structures. The results of these simulations suggest that the sphere phase is stable under weak electric fields, but a threshold electric intensity exists for the sphere-to-cylinder phase transition. In addition, we also studied the kinetic pathways of the transition of the lamellar phase to the hexagonal cylinder phase of the asymmetric diblock copolymers under electric fields. Hexagonal cylinder structures form when the lamellar phase is subjected to a sudden temperature jump. The scattering functions suggest that the hexagonal cylinder structures are very regular and possess very few flaws. 相似文献
970.
中性载体ETH1616推动质子在油/水界面的转移 总被引:1,自引:0,他引:1
本文用循环伏安法和循环电流扫描计时电位法研究了中性载体ETH1616(N,N-bjs-heptylethyldiamide)推动质子在油/水界面的转移过程,探讨了有关转移过程的机理,测定了相应的扩散系数和配合物的稳定常数。 相似文献