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Interface Interaction (interface + interaction)

Distribution by Scientific Domains

Polymers and Materials Science	40%

Selected Abstracts

In situ deformation of thin films on substrates

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2009
Marc Legros
Abstract Metallic thin-film plasticity has been widely studied by using the difference between the coefficients of thermal expansion of the film and the underlying substrate to induce stress. This approach is commonly known as the wafer curvature technique, based on the Stoney equation, which has shown that thinner films have higher yield stresses. The linear increase of the film strength as a function of the reciprocal film thickness, down to a couple hundred nanometers, has been rationalized in terms of threading and interfacial dislocations. Polycrystalline films also show this kind of dependence when the grain size is larger than or comparable to the film thickness. In situ TEM performed on plan-view or cross-section specimens faithfully reproduces the stress state and the small strain levels seen by the metallic film during wafer curvature experiments and simultaneously follows the change in its microstructure. Although plan-view experiments are restricted to thinner films, cross-sectional samples where the film is reduced to a strip (or nanowire) on its substrate are a more versatile configuration. In situ thermal cycling experiments revealed that the dislocation/interface interaction could be either attractive or repulsive depending on the interfacial structure. Incoherent interfaces clearly act as dislocation sinks, resulting in a dislocation density drop during thermal cycles. In dislocation-depleted films (initially thin or annealed), grain boundaries can compensate for the absence of dislocations by either shearing the film similarly to threading dislocations or through fast diffusion processes. Conversely, dislocations are confined inside the film by image forces in the cases of epitaxial interfaces on hard substrates. To increase the amount of strain seen by a film, and to decouple the effects of stress and temperature, compliant substrates can also be used as support for the metallic film. The composite can be stretched at a given temperature using heating/cooling straining holders. Other in situ TEM methods that served to reveal scaling effects are also reviewed. Finally, an alternate method, based on a novel bending holder that can stretch metallic films on rigid substrates, is presented. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source]

Novel high-dielectric-permittivity poly(vinylidene fluoride)/polypropylene blend composites: The influence of the poly(vinylidene fluoride) concentration and compatibilizer

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007
Zhi-Min Dang
Abstract Novel high-dielectric-permittivity poly(vinylidene fluoride) (PVDF)/polypropylene (PP) blend composites were prepared via a blending technology, and their dielectric properties were studied over wide ranges of temperatures and frequencies. To improve the interface bonding between PVDF and PP, a suitable compatibilizer, polypropylene- graft -maleic anhydride (PP- g -MAH), was employed. The results showed that the concentration of PVDF in the composites dominated the changes in the dielectric properties and that the use of PP- g -MAH could improve the interface interaction between PVDF and PP, resulting in an increase in the dielectric permittivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Effect of high-energy vibro-milling of filler on the mechanical properties of filled high-density polyethylene

POLYMER COMPOSITES, Issue 3 2003
Shaoyun Guo
The effect of high-energy mechanical milling of CaCO3 (calcium carbonate) and STC (a mixture of sericite, tridymite and cristobalite) on mechanical properties, rheological and dynamical mechanical behavior of high-density polyethylene (HDPE)/CaCO3 and HDPE/STC was studied through SEM (scanning electron microscope), DMTA (dynastic mechanical test analysis), mechanical and melt rheological properties tests. The experimental results show that addition of fillers treated by coupling agent and vibromilling to HDPE makes the impact strength of HDPE greatly increased. The impact strength of HDPE/treated CaCO3 (60/40) and HDPE/treated STC (60/40) is ca. 4 and 3 times respectively as high as that of HDPE. The SEM micrographs of impact fractured surfaces of treated fillers filled HDPE show extensive plastic deformation of HDPE matrix, indicating that the plastic deformation of matrix induced by the treated fillers is the main contribution for absorbing a great amount of impact energy. This is the reason why the impact strength of HDPE greatly increases with addition of coupling agent and vibromilling treated fillers. The intensity of , relaxation peak of HDPE in HDPE/treated CaCO3 on tan, vs. temperature curve increases and the peak shifts to higher temperature due to its stronger interface interaction as compared with that of HDPE/untreated CaCO3. [source]

Contributions of hydrophobic domain interface interactions to the folding and stability of human ,D-crystallin

PROTEIN SCIENCE, Issue 3 2005
Shannon L. Flaugh
Abstract Human ,D-crystallin (H,D-Crys) is a monomeric eye lens protein composed of two highly homologous ,-sheet domains. The domains interact through interdomain side chain contacts forming two structurally distinct regions, a central hydrophobic cluster and peripheral residues. The hydrophobic cluster contains Met43, Phe56, and Ile81 from the N-terminal domain (N-td) and Val132, Leu145, and Val170 from the C-terminal domain (C-td). Equilibrium unfolding/refolding of wild-type H,D-Crys in guanidine hydrochloride (GuHCl) was best fit to a three-state model with transition midpoints of 2.2 and 2.8 M GuHCl. The two transitions likely corresponded to sequential unfolding/refolding of the N-td and the C-td. Previous kinetic experiments revealed that the C-td refolds more rapidly than the N-td. We constructed alanine substitutions of the hydrophobic interface residues to analyze their roles in folding and stability. After purification from E. coli, all mutant proteins adopted a native-like structure similar to wild type. The mutants F56A, I81A, V132A, and L145A had a destabilized N-td, causing greater population of the single folded domain intermediate. Compared to wild type, these mutants also had reduced rates for productive refolding of the N-td but not the C-td. These data suggest a refolding pathway where the domain interface residues of the refolded C-td act as a nucleating center for refolding of the N-td. Specificity of domain interface interactions is likely important for preventing incorrect associations in the high protein concentrations of the lens nucleus. [source]