Two-phase material

Shock-recovery experiments by Gray [10] were conducted to assess directly if the strain-path reversal inherent to the shock contains a traditional microstructurally controlled Bauschinger effect for a shock-loaded two-phase material. Two samples of a polycrystalline Al-4 wt.% Cu alloy were shock loaded to 5.0 GPa and soft recovered in the same shock assembly to assure identical shock-loading conditions. The samples had two microstructural... 

The conventionally covalently cross-linked rubbers and plastics cannot dissolve without chemical change. They will, however, swell in solvents of similar solubility parameter, the degree of swelling decreasing with increase in cross-link density. The solution properties of the thermoelastomers which are two-phase materials are much more complex, depending on whether or not the rubber phase and the resin domains are dissolved by the solvent. 

Following the success in blending rubbery materials into polystyrene, styrene-acrylonitrile and PVC materials to produce tough thermoplastics the concept has been used to produce high-impact PMMA-type moulding compounds. These are two-phase materials in which the glassy phase consists of poly(methyl methacrylate) and the rubbery phase an acrylate polymer, usually poly(butyl acrylate Commercial materials of the type include Diakon MX (ICI), Oroglas... 

What was recognised from the beginning was that colloidal solutions are two-phase materials. 

Indeed, the self-consistent model averages the stresses and strains in either phase of a two-phase material, and it determines them, by solving separate problems, whose superposition yields the final configuration of the model 7). 

There is currently considerable interest in processing polymeric composite materials filled with nanosized rigid particles. This class of material called "nanocomposites" describes two-phase materials where one of the phases has at least one dimension lower than 100 nm [13]. Because the building blocks of nanocomposites are of nanoscale, they have an enormous interface area. Due to this there are a lot of interfaces between two intermixed phases compared to usual microcomposites. In addition to this, the mean distance between the particles is also smaller due to their small size which favors filler-filler interactions [14]. Nanomaterials not only include metallic, bimetallic and metal oxide but also polymeric nanoparticles as well as advanced materials like carbon nanotubes and dendrimers. However considering environmetal hazards, research has been focused on various means which form the basis of green nanotechnology. 

The horizontal portion of the plot in Figure 23.6 represents the equilibrium mass uptake—the amount absorbed at equilibrium whose magnitude is influenced by the solubility parameter 8 (Section 23.4.3.1). In reality, coefficient D quite often varies with concentration, so that the overall plot takes on a sigmoid shape (see Section 23.4.4.3), although a horizontal portion is still usually achieved eventually if it is not, the elastomer is possibly a two-phase material (a blend), with one phase much slower at absorbing the incoming liquid. 

With this imaging system it is possible to study virtually all metals and alloys, many semiconductors and some ceramic materials. The image contrast from alloys and two-phase materials is difficult to predict quantitatively, as the effects of variations in chemistry on local field ion emission characteristics are not fully understood. However, in general, more refractory phases image more brightly in the FIM. Information regarding the structure of solid solutions, ordered alloys, and precipitates in alloys has been obtained by FIM. 

Affected by multiple scattering are, in particular, porous materials with high electron density (e.g., graphite, carbon fibers). The multiple scattering of isotropic two-phase materials is treated by Luzatti [81] based on the Fourier transform theory. Perret and Ruland [31,82] generalize his theory and describe how to quantify the effect. For the simple structural model of Debye and Bueche [17], Ruland and Tompa [83] compute the effect of the inevitable multiple scattering on determined structural parameters of the studied material. 

Figure 8.15. The invariant as a function of the composition of a two-phase material. Between 30 and 70 vol.-% the scattering power is almost constant. The regions 0-30 vol.-% and 70 -100 vol.-% exhibit almost linear relations... 

If we know that in our two-phase material the volume fraction of one fraction is between 30 and 70%, then the term v (1 - v) 0.23 is constant to a first approximation (cf. Fig. 8.15). If in this case during the experiment a considerable change of the invariant is observed, it is probably caused by a variation of the contrast67. If, on the other hand, the contrast is known to be constant and nanostructure is evolving from a homogeneous phase, the initial increase of the scattering power is proportional to the change of the materials composition. 

Koufopoulos T. and Theocaris P.S. (1969). Shrinkage stresses in two-phase materials, J. Composite Muter. 3, 308-320,... 

Blends of PE, of PMMA, andofPVA(O) with HPL of varying molecular weight produce two-phase materials. Blends of HPL with PVA (> 0) exhibit at least partial miscibility. 

Thus different phase behaviors of polyrotaxanes induced different thermal transitions. One-phase or two-phase materials can be obtained simply by proper choice of the components. The easy introduction of highly flexible cyclic components such as crown ethers with low T% surely expands the applications of otherwise brittle polymers into the low temperature range and also improves elasticity. The plasticizing effect of the crown ether is different from that of a normal plasticizer, because the cyclic is permanently connected to the backbone and no migration can occur. 

Liquid crystal forming materials have thus five possible pure phases (fully ordered -crystal, LC-glass, amorphous glass, liquid crystal, and isotropic melt). In addition, there may be four two-phase materials (fully ordered crystal and LC-glass, fully ordered crystal and amorphous glass, fully ordered crystal and isotropic melt, and fully ordered crystal and liquid crystal). The correlations between these phases are shown in Fig. 3. 

A threshold level of interfacial adhesion is also necessary to produce a triaxial tensile state around rubber particles as the result of the cure process. When the two-phase material is cooled from the cure temperature to room temperature, internal stresses around particles are generated due to the difference of thermal expansion coefficients of both phases. If particles cannot debond from the matrix, this stress field magnifies the effect produced upon mechanical loading. 

Another method, applied to evaluate the connectivity of two-phase materials, is based on the Euler-Poincare formula that establishes for a single solid, independently on its complexity, the following rule ... 

For a planar surface between two phases, material can be added to one of the phases at constant area as well as constant temperature and constant pressure. However, if we add material to the small drop at constant temperature and constant pressure on the large phase, the area of the drop must change. Now... 

Ion-beam thinning Universally applicable good for two-phase materials and chemically resistant materials large thin areas reproducible Slow, ion-beam damage and structural alterations often possible... 

Each two-dimensional sample from a three-dimensional system represents the intersection of a test plane with the sample. The relationships described above are useful for predicting mean properties of the three-dimensional image based on measurements from planar samples. To predict more detailed properties, such as the distribution of particle size in a two phase material, more... 

General properties of random two-phase materials analogies bounds, dilute suspensions at order 0 and 2. 

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