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Particle Content (particle + content)

Distribution by Scientific Domains

Polymers and Materials Science	71%

Selected Abstracts

Crust strength: a wind tunnel study of the effect of impact by saltating particles on cohesive soil surfaces

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2001
M. A. Rice
Abstract A wind tunnel study examined the effect of distributions of saltating particles on sediment surfaces which were characterized by distributions of their tensile strength. The sediments consisted of varying proportions of large sand-sized particles with a fine particle cement. The energies of the impacting particles and the surface strengths were compared with the mass of material lost from the surface. It is important to consider distributions of parameters rather than mean values only, since abrasion and erosion may occur from surfaces not predicted from average strength and saltation velocities. At the impact velocities used in this study (mean velocity 4·4 m s,1, with standard deviation of 0·51), surfaces containing less than 12 per cent fine material were easily eroded, but insignificant erosion occurred when the fine particle content exceeded 60 per cent. Small amounts of cementing material were easily ruptured, allowing the large sand grains to be moved (largely in creep) by the bombarding particles. A significant amount of energy was lost to the bed. As the percentage of fine material increased, the surface became more difficult to break up and less energy was lost to the bed. The probability that erosion will occur for known energy distributions of impacting particles and surface strength can be calculated and the mass loss increases exponentially with a decrease in the percentage of fine cementing particles. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A Facile Route to ZnS,Polymer Nanocomposite Optical Materials with High Nanophase Content via ,-Ray Irradiation Initiated Bulk Polymerization,

ADVANCED MATERIALS, Issue 9 2006
C. Lü
Transparent ZnS/polymer bulk nanocomposites with high particle contents are prepared via ,-ray irradiation initiated polymerization. This strategy involves the design and tailoring of the surface of the nanoparticles and choice of the monomer as well as the selection of the polymerization route. The figure shows a TEM image of a bulk nanocomposite containing mercaptoethanol-capped ZnS with a particle content of 20,wt,%. [source]

A reactive polymer for toughening epoxy resin

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
Hsu-Chiang Kuan
Abstract Epoxy resins are hardly toughened by low weight content of tougheners. In this study, 5 wt % polyurea was adopted to significantly toughen piperidine-cured epoxy, as fracture toughness improved from 0.78 to 1.98 MPa m1/2. We focused on the reactions and morphology evolution of epoxy/polyurea mixture. The polyurea molecular weight was reduced by the exchange reactions of polyurea with epoxy during mixing, as evidenced by gel permeation chromatograph and Fourier transform infrared spectroscopy. As a result, epoxy molecules were chemically bonded with polyurea, improving particle content and interface thickness. Transmission electron microscope observation shows that (a) polyurea in situ formed nanoparticles in matrix which subsequently aggregate into micron-sized particles of thick interface with matrix; and (b) the particles became less stainable with increasing the mixing time, because the reactions promoted high levels of crosslink density of the particles which were thus more resistant to the diffusion of staining chemicals. Longer mixing time improved, obviously, the fracture toughness of epoxy/polyurea composite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Simultaneously improved toughness and dielectric properties of epoxy/core-shell particle blends

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008
Weitao Wan
Abstract Epoxy/core-shell particle blends were prepared using a diglycidylether of bisphenol A epoxy and acrylics-type core-shell particles. The impact strength of the blends was tested, and the result showed that the epoxy was greatly toughened with optimum core-shell particle content. Meanwhile, the dielectric properties of both epoxy and its blends were investigated using a broadband dielectric analyzer. It was found that the dielectric constant of the epoxy blends with lower core-shell particle content were less than that of the epoxy in the investigated frequency range, while the dielectric loss was less than that of the neat epoxy over a low frequency range, even for the epoxy blends with the optimum core-shell particle content. The dielectric breakdown strength of the epoxy blends at room and cryogenic temperature were also investigated. To identify the primary relationship of the above properties and structure of the epoxy blends, the microstructure of the core-shell particle and the morphology of the samples were observed by transmission electron microscopy and scanning electron microscopy. It was considered that these epoxy/core-shell particle blends with improved toughness and desirable dielectric properties could have a potential application in the insulation of electronic packaging system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source]

Mechanism of interactions of eggshell microparticles with epoxy resins

POLYMER ENGINEERING & SCIENCE, Issue 7 2009
Genzhong Ji
Large surface-area microparticles of natural chicken eggshell were prepared and characterized to illustrate how such particles can improve the toughness of epoxy resins. A small amount of organic compounds, in particular proteins, were found to be present in the microparticles and beneficial to the enhancement of the mechanical properties of the epoxy resins. Scanning electron microscopic analysis of the rough fracture surfaces show that there are full of plastic deformation, voids, cavities, and debonding phenomena in the microparticle-filled composites. Positron annihilation study indicates that the lifetime of ,3 o-Ps varies and the corresponding intensity of I3 becomes weak with the increase of eggshell particle content, which indicates that there is a good interaction between the epoxy resin and the filling particles. This gives rise to significant improvement in the toughness of the filled resin. The impact strength of the epoxy resin composite reaches 16.7 kJ/m2 compared with 9.7 kJ/m2 of neat epoxy resin when the epoxy resin composite is filled with only 5 mass% eggshell particles. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

Radion-induced gravitational wave oscillations and their phenomenology

ANNALEN DER PHYSIK, Issue 6 2003
A.O. Barvinsky
Abstract We discuss the theory and phenomenology of the interplay between the massless graviton and its massive Kaluza-Klein modes in the Randall-Sundrum two-brane model. The equations of motion of the transverse traceless degrees of freedom are derived by means of a Green function approach as well as from an effective nonlocal action. The second procedure clarifies the extraction of the particle content from the nonlocal action and the issue of its diagonalization. The situation discussed is generic for the treatment of two-brane models if the on-brane fields are used as the dynamical degrees of freedom. The mixing of the effective graviton modes of the localized action can be interpreted as radion-induced gravitational-wave oscillations, a classical analogy to meson and neutrino oscillations. We show that these oscillations arising in M-theory-motivated braneworld setups could lead to effects detectable by gravitational-wave interferometers. The implications of this effect for models with ultra-light gravitons are discussed. [source]