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911.
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Impact of cellulose nanocrystal aspect ratio on crystallization and reinforcement of poly(butylene adipate‐co‐terephthalate) 下载免费PDF全文
Marcos Mariano Christine Chirat Nadia El Kissi Alain Dufresne 《Journal of Polymer Science.Polymer Physics》2016,54(22):2284-2297
Cellulose nanocrystals (CNCs) are appealing nanomaterials for the reinforcement of polymeric materials. It is now well established that high mechanical properties are obtained when preparing the nanocomposite by casting/evaporation methods and using CNC contents above the percolation threshold. This phenomenon results from the formation of a stiff CNC network within the matrix meaning that the properties of the matrix play only a limited role on the mechanical properties of the material when the matrix is in the rubbery state. In subpercolation concentration or when using a different processing technique, the level of understanding is less clear, mainly when the CNC‐induced crystallization of the matrix interferes with the reinforcing mechanism. In this study, we used CNCs with different aspect ratios to prepare nanocomposites by extrusion with polybutyrate adipate terephthalate as matrix. The impact of CNC on the crystallinity of the matrix and mechanical properties of the nanocomposite has been investigated. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2284–2297 相似文献
915.
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917.
Relativistic nonlinear models based on the Hartree and Hartree-Fock approximations, including the σ, ω, π, and ρ mesons, are worked out to explore the behavior of the nuclear charge radii and the binding energies of several isotopic chains.
We find a correlation between the magnitude of the anomalous kink effect (KE) in the Pb isotopic family and the compressibility
modulus (K) of nuclear matter. The KE appears to be sensitive, in particular, to the mechanisms which control the K value.
The influence of the symmetry energy on the Ca isotopic chain is also studied. The behavior of the charge radii of single-particle
states for some special cases and its repercussion on the nuclear charge radius is analyzed. The effect of pairing correlations
on the models improves considerably the quality of the results in both binding energy and KE. 相似文献
918.
The macroscopic pressure difference between two immiscible, incompressible fluid phases flowing through homogeneous porous media is considered. Starting with the quasi-static motions of two compressible fluids, with zero surface tension, it is possible to construct a complete system of equations in which all parameters are clearly defined by physical experiments. The effect of surface tension is then formally included in the definition of the specific process under consideration. Incorporating these effects into the pressure equations and taking the limit as compressibilities go to zero, the independent pressure equations are shown to yield indeterminate forms. However, the difference of the two pressure equations is found to yield a new process-dependent dynamical equation.List of Symbols
J
LeverettJ function
-
K
i
bulk modulus of fluidi (i=1, 2)
-
K
s
bulk modulus of solid
-
K
permeability
-
P
fractional porosity of the wetting phase (in LeverettJ function)
-
p
i
macroscopic pressure of fluidi (i=1, 2)
-
Q
ij
Mobilities (i, j=1, 2) (cf. de la Cruz and Spanos, 1983)
-
V
i
macroscopic velocity vector of fluidi (i=1, 2)
Greek Letters
surface tension
-
i
compliance factor for fluidi (i=1, 2) for incompressible flow defined in equations (29) and (30) (process-dependent)
-
compliance factor for the flow of two incompressible fluid (cf. eqns. (32) and (33) for relation to
i)
-
i
compliance factor for a compressible fluid (i=1, 2) (process-dependent) (cf. de la Cruzet al., 1989, 1993)
-
i
modification to static compliance factor for fluidi (i=1, 2) as a result of quasi-static flow
-
i
fraction of space occupied by fluidi (i=1, 2) measured dynamically
-
i
o
fraction of space occupied by fluidi (i=1, 2) measured statically
-
i
shear viscosity of fluidi (i=1, 2)
-
i
bulk viscosity of fluidi (i=1, 2)
-
i
density of fluidi (i=1, 2) 相似文献
919.
The concept of improving oil recovery through polymer flooding is analysed. It is shown that while the injection of a polymer solution improves reservoir conformance, this beneficial effect ceases as soon as one attempts to push the polymer solution with water. Once water injection begins, the water quickly passes through the polymer creating a path along which all future injected water flows. Thus, the volume of the polymer slug is important to the process and an efficient recovery would require that the vast majority of the reservoir be flooded by polymer. It is also shown that the concept of grading a polymer slug to match the mobilities of the fluids at the leading and trailing edges of a polymer slug does not work in a petroleum reservoir. While this process can supply some additional stability to the slug, it is shown that for the purposes of enhanced oil recovery this additional stability is not great enough to be of any practical use. It is found that in this case the instability has simply been hidden in the interior of the slug and causes the same sort of instability to occur as was the case for the uniform slug. 相似文献
920.
Marcos Couto Mauricio Cabrera Gustavo A. Echeverría Oscar E. Piro Mercedes González Hugo Cerecetto 《Molecular diversity》2014,18(2):285-294
In the course of our studies on 3 $H$ -1,2-dithiole-3-thione synthesis, a serendipitous reactivity with $\alpha $ -haloketones, in the presence of excess of potassium iodide, has been observed. Instead of the expected reaction of the nucleophile in a remote point of the molecule, we have obtained a product resulted from the electrophile character of the thiocarbonyl moiety on the 3-position of the 1,2-dithiole. In order to obtain an efficient protocol in terms of energy efficiency, this methodology was studied under conventional and microwave heating with similar or better results in the latter conditions. Simplicity and great efficiency in this one-step transformation are some of the advantages of this reaction. Moreover, the results can be explained according to the Pearson’s hard and soft acid base theory. 相似文献