Fluoro-organofunctional silicon compounds. Synthesis of acetoxy,carbethoxy and hydroxy derivatives

The synthesis of fluoro-organosilicon compounds containing acetoxy, carbethoxy, or hydroxy groups in the organic portion of the molecule is described.     

Dual reciprocal states in finite elasticity

For certain equilibrium states of an elastic body dual states (in the sense of Hill [1] and Ogden [2]) can be constructed, roughly speaking by interchanging the roles of stress and deformation. Furthermore, for each of the original and dual states, a reciprocal state (in the sense of Adkins [3] and Shield [4]) can be found by interchanging initial and final coordinates. Although the resulting reciprocal states are not dually related, a closed chain of eight dual and reciprocal states can be constructed. In the case of plane strain simple formulae relating the strain-energy functions for all eight states can be written down.     

Cooling of melts: kinetic stabilization and polymorphic transitions in the KInSnSe 4 system

Through a flame-melting/rapid-cooling process, metastable forms of solid state compounds can be discovered. We describe here an example where both slow and rapid crystallizations of a stoichiometric "KInSnSe(4)" melt give rise to kinetic forms of KInSnSe(4). These forms (alpha- and beta-) convert to the thermodynamically stable gamma-form upon heating below the melting point.     

The Characterization of Molecular Alkali‐Metal Azides.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.     

A Note on Residual Stress, Lattice Orientation and Dislocation Density in Crystalline Solids

The theory of residually stressed crystals is discussed in the context of the finite deformation theory of elastic?Cplastic solids. Here residual stress is assumed to be due to the prior plastic flow of a single crystal. On the basis of recent experiments, as well as the structure of the underlying theory, we advance the view that the lattice orientation field should be regarded as data. This stands in contrast to the classical theory in which dislocation density is assigned.     

On the overall moduli of non-linear elastic composite materials

From the work of R. Hill on constitutive macro-variables it is known that for an inhomogeneous elastic solid under finite strain an overall elastic constitutive law may be defined. In particular, the volume average of the strain energy of the solid is a function only of the volume-averaged deformation gradient. In view of the importance of this result it is re-derived in this paper as a prelude to a discussion of composite materials. A composite material consisting of a dilute suspension of initially spherical inclusions embedded in a matrix of different material is considered. For second-order isotropic elasticity theory an expression for the overall bulk modulus of the composite material is obtained in terms of the moduli of the constituents. When the inclusions are vacuous a known result for the bulk modulus of porous materials is recovered. In certain situations the strengthening/ weakening effects of the inclusions are less pronounced in the second-order theory than in the linear theory.     

On tensile instabilities and ellipticity loss in fiber-reinforced incompressible non-linearly elastic solids

Loss of ellipticity and associated failure in fiber-reinforced non-linearly elastic solids is examined for uniaxial plane deformations. We consider separately fiber reinforcement that either endows the material with additional stiffness only in the fiber direction or introduces additional stiffness under shear deformations. In the first case it is shown that loss of ellipticity under tensile loading in the fiber direction corresponds to a turning point of the nominal stress and requires concavity of the Cauchy stress–stretch curve. For the second example loss of ellipticity occurs after the nominal stress maximum and prior to a turning point of the Cauchy stress.     

Two-dimensional wave propagation in a rotating elastic solid with voids

Two-dimensional wave propagation is studied in an isothermal linear isotropic elastic material with voids rotating with constant angular velocity based on a theory of elastic material with voids developed by Ie?an (1986) in the thermoelastic context. It is found that there exist three coupled plane waves propagating with distinct phase speeds. The presence of voids and the rotation of the medium are responsible for this coupling. In the absence of voids, the classical longitudinal and transverse waves are found to be coupled through the rotation of the medium. At very large frequency or when the angular rotation is very small relative to the wave frequency the waves are decoupled and propagate with distinct phase speeds. These are (i) a longitudinal wave, (ii) a transverse wave and (iii) a longitudinal wave corresponding to the change in void volume fraction. The first two correspond to the waves of classical elasticity, while the third is new and arises from the presence of the voids. The results are illustrated graphically.