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The Matrix Material (the + matrix_material)

Distribution by Scientific Domains

Polymers and Materials Science	37%

Selected Abstracts

Low-Temperature Plasticity of Naturally Deformed Calcite Rocks

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2002
LIU Junlai
Abstract Optical, cathodoluminescence and transmission electron microscope (TEM) analyses were conducted on four groups of calcite fault rocks, a cataclastic limestone, cataclastic coarse-grained marbles from two fault zones, and a fractured mylonite. These fault rocks show similar microstructural characteristics and give clues to similar processes of rock deformation. They are characterized by the structural contrast between macroscopic cataclastic (brittle) and microscopic mylonitic (ductile) microstructures. Intragranular deformation microstructures (i.e. deformation twins, kink bands and microfractures) are well preserved in the deformed grains in clasts or in primary rocks. The matrix materials are of extremely fine grains with diffusive features. Dislocation microstructures for co-existing brittle deformation and crystalline plasticity were revealed using TEM. Tangled dislocations are often preserved at the cores of highly deformed clasts, while dislocation walls form in the transitions to the fine-grained matrix materials and free dislocations, dislocation loops and dislocation dipoles are observed both in the deformed clasts and in the fine-grained matrix materials. Dynamic recrystallization grains from subgrain rotation recrystallization and subsequent grain boundary migration constitute the major parts of the matrix materials. Statistical measurements of densities of free dislocations, grain sizes of subgrains and dynamically recrystallized grains suggest an unsteady state of the rock deformation. Microstructural and cathodoluminescence analyses prove that fluid activity is one of the major parts of faulting processes. Low-temperature plasticity, and thereby induced co-existence of macroscopic brittle and microscopic ductile microstructures are attributed to hydrolytic weakening due to the involvement of fluid phases in deformation and subsequent variation of rock rheology. During hydrolytic weakening, fluid phases, e.g. water, enhance the rate of dislocation slip and climb, and increase the rate of recovery of strain-hardened rocks, which accommodates fracturing. [source]

Applying SEM-Based X-ray Microtomography to Observe Self-Healing in Solvent Encapsulated Thermoplastic Materials,

ADVANCED ENGINEERING MATERIALS, Issue 3 2010
Steven D. Mookhoek
In this work X-ray microtomography was used to observe fracture and healing processes in a liquid-based self-healing thermoplastic material. The method was able to produce data of sufficient resolution (<10,,m) to observe ,60,,m microcapsules containing solvent within a polymeric material and in particular their behavior around a crack zone after fracture and healing. The reconstructed data showed the distribution of filled and several empty microcapsules within the matrix material. Additional color segmentation and 3D rendering of the data unambiguously demonstrated a large concentration of ruptured microcapsules near the fracture surfaces, covering ,75,,m span on both sides of the crack. A close investigation of the crack area confirmed the presence of healed and non-healed regions. Further analysis of the segmented data allowed a quantitative determination of the release of the encapsulated solvent. [source]

Dynamic numerical simulations of void growth and coalescence with stress triaxiality maintained constant,Application to ductile solids with secondary voids

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2008
L. Siad
Abstract Dynamic explicit finite element analysis is used to investigate void growth and plastic collapse of an axisymmetric unit cell model with a primary spherical void imbedded in a porous matrix material. The Gurson,Tvergaard,Needleman homogenized model is used to describe the plastic behaviour of the matrix material. The simulations are performed under large strain conditions for varying secondary void volume fractions and quasi-static loading controlled by constant stress triaxiality. The proposed accomplishment of constant stress triaxiality associated with dynamic explicit computations provides a method allowing to trace the collapse of the unit cell from the onset of coalescence to practically its final failure. Consistent with experimental and theoretical results available in the literature, the obtained results substantiate the sensitivity of coalescence to the presence of secondary voids. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Pitting corrosion on 316L pipes in terephthalic acid (TA) dryer

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2009
Y. Gong
Abstract Grade 316L is a type of austenitic stainless steel with ultra-low carbon content and it exhibits superior corrosion resistance. However, pitting is always observed in 316L steel when it is exposed to media containing halide ions. In the present study, we found that in the presence of acetate acid (HAc) containing chloride or bromide ions, pitting occurred on the surface of the rotary steam pipes with the matrix material of 316L steel in terephthalic acid (TA) dryer. In order to identify the causes of the failure, metallographic structures and chemical compositions of the matrix material were inspected by an optical microscope (OM) and a photoelectric direct reading spectrometer. Beside these, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) as well as ion chromatography (IC) were used to analyze the micromorphologies of the corrosion pits and the chemical compositions of the corrosion deposits within them. Analysis of the results revealed the sources of halide ions and the factors accelerating the corrosion rate. Beside these, detailed mechanisms of pitting were discussed and six out of all the seven theoretical morphologies of pitting features were obtained in practice. [source]

In situ reinforcement of poly(butylene terephthalate) and butyl rubber by liquid crystalline polymer

POLYMER COMPOSITES, Issue 5 2009
S. Kumar
Ternary in situ butyl rubber (IIR)/poly(butylene terephthalate) (PBT) and liquid crystalline polymer (LCP) blends were prepared by compression molding. The LCP used was a versatile Vectra A950, and the matrix material was IIR/PBT 50/50 by weight. Morphological, thermal, and mechanical properties of blends were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry, and thermogravimetric analysis (TGA). Microscopy study (SEM) showed that formation of fibers is increasing with the increasing amount of LCP A950. Microscopic examination of the fractured surface confirmed the presence of a polymer coating on LCP fibrils. This can be attributed to some interactions including both chemical and physical one. The increased compatibility in polymer blends, consisting of IIR/PBT, by the presence of LCP A950 may be explained by the adsorption phenomena of the polymer chains onto the LCP fibrils. SEM and AFM images provided the evidence of the interaction between IIR/PBT and the LCP. Dynamic mechanical analyses (DMA) and TGA measurements showed that the composites possessed a remarkably higher modulus and heat stability than the unfilled system. Storage modulus for the ternary blend containing 50 wt% of LCP exhibits about 94% increment compared with binary blend of IIR/PBT. From the above results, it is suggested that the LCP A950 can act as reinforcement agent in the blends. Moreover, the fine dispersion of LCP was observed with no extensional forces applied during mixing, indicating the importance of interfacial adhesion for the fibril formation. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

Synthesis and Optical Properties of Europium-Complex-Doped Inorganic/Organic Hybrid Materials Built from Oxo,Hydroxo Organotin Nano Building Blocks

CHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2010
Wei-Qiang Fan Dr.
Abstract Hybrid materials doped with novel europium complexes were synthesized using PMMA- co -Sn12Clusters (copolymers from oxohydroxo-organotin dimethacrylate and methylmethacrylate) as the matrix material. Two types of hybrid materials were obtained: the physically doped product, PMMA- co -Sn12Cluster/Eu(TTA)3phen, and the grafted product, PMMA- co -Sn12Cluster- co -[EuAA(TTA)2phen] (TTA=2-thenoyltrifluoroacetone, phen=phenanthroline and AA=acrylic acid). The hybrid materials exhibited characteristic luminescence of the Eu3+ ions, and also showed relative especial optical properties compared with samples just using PMMA as the matrix material. The PMMA- co -Sn12Cluster matrix exhibited a high physical doping quantity of [Eu(TTA)3phen], which can be attributed to the special structure of this kind of hybrid material. GPC (gel-permeation chromatography), TGA (thermogravimetric analysis), SEM, 1H,NMR, ICP (inductively coupled plasma), 119Sn,NMR, FTIR, and diffuse reflectance techniques were employed to characterize the structures and properties of these hybrid materials. [source]

Thermal expansion co-efficient of nanotube,metal composites

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009
Sheikh M. Uddin
Abstract Thermal expansion exhibits considerable challenges developing residual stresses at the interfaces of different materials treated at high temperature. Electrical devices containing materials with different thermal expansion behaviour very often suffer this problem. Thermal expansion co-efficient (TEC) of different metals can be tuned by using carbon nanotube (CNT). Metal matrix composites (MMCs) using CNT are fabricated by hot-press sintering method and TEC of the composites are investigated throughout a wide range of temperature (,155 to 275,°C). Reduction of TEC of the composite materials was observed up to 20% compared to that of pure metals. The effect of CNTs in the matrix materials and the mechanism behind the improvement are explained from the microscopic investigation of the composites. [source]