Deformation in the solid state

Asthenosphere The portion of the Earth s mantle below the lithosphere, 10s to 100s of kilometers below the surface, that is actively convecting at rates of centimeters per year and deforming in the solid state. Its temperature is close to the melting point so that it is presumed to be the source region for basalt, the most voluminous product of mantle melting. 

The precise mechanisms by which polyethylene deforms in the solid state are not rigorously understood. Various schemes have been proposed to explain the... 

The IR spectra of 2,3 -bipyridine,i " - ° - i 2,4 -bipyridine, " 3,3 -bipyridine, °° and 3,4 -bipyridine °°- have all been reported. From IR spectral assignments it is suggested that 2,3 - and 3,3 -bipyridines adopt the cisoid conformation. The IR spectrum of 4,4 -bipyridine both in the solid state and in solution has attracted much attention, and the spectrum has been fully interpreted.4,4 -Bipyridine has been included in a study of the use of IR intensities as a quantitative measure of intramolecular interactions. Interestingly, changes in the intensities of IR bands due to aromatic ring deformations and C—H deformations on going from the solid to the molten state have been used to show that the aromatic rings of 2,2 - and 4,4 -bipyridines are not coplanar in the liquid phase. The IR spectra of salts of 4,4 -bipyridine have been discussed. ... 

Decreased mobility of adsorbed chains has been observed and proved in many cases both in the melt and in the solid state [52-54] and changes in composite properties are very often explained by it [52,54]. Overall properties of the interphase, however, are not completely clear. Based on model calculations the formation of a soft interphase is claimed [51], while in most cases the increased stiffness of the composite is explained by the presence of a rigid interphase [55,56]. The contradiction obviously stems from two opposing effects. Imperfection of the crystallites and decreased crystallinity of the interphase should lead to lower modulus and strength and larger deformability. Adhesion and hindered mobility of adsorbed polymer chains, on the other hand, decrease deformability and increase the strength of the interlayer. 

The heptafluoride has been reported not to have a pentagonal bipyramidal arrangement in the solid state,49 although the considerable difficulties involved in the crystal structure determination lead to less accurate results than could be desired.50 In the vapour state electron diffraction results51 show that the pentagonal bipyramidal arrangement is present but the molecule is non-rigid, with deformation from D5h symmetry, and this may account for the solid state structure. 

By necessity, the treatment of solid state kinetics has to be selective in view of the myriad processes which can occur in the solid state. This multitude is mainly due to three facts 1) correlation lengths in crystals are often much larger than in fluids and may comprise the whole crystal, 2) a structure element is characterized by three parameters instead of only by two in a liquid (chemical species, electrical charge, type of crystallographic site), and 3) a crystal can be elastically stressed. The stress state is normally inhomogeneous. If the yield strength is exceeded, then plastic deformation and the formation of dislocations will change the structural state of a crystal. What we aim at in this book is a strict treatment of concepts and basic situations in a quantitative way, so far as it is possible. In contrast, the often extremely complex kinetic situations in solid state chemistry and materials science will be analyzed in a rather qualitative manner, but with clearcut thermodynamic and kinetic concepts. 

The X-ray structure of l-piperidino-2,4-dinitrobenzene was published (95MI801). The piperidine ring exhibits a slightly distorted chair conformation the N-atom is almost in a plane due to the partial C,N double bond, and the aromatic ring shows a slight boat deformation with the o/p-nitro groups twisted out of plane. UV and NMR data indicate that the molecule in solution presents a conformation similar to that in the solid state. In the crystalline anhydrous N-methylpiperidine betaine 86 (cf. Scheme 33) the piperidine ring adopts the usual chair conformation... 

In the solid state deformation, the nonlinear viscoelastic effect is most clearly shown in the yield behavior. The type of stresses applied to a system has little effect on the linear viscoelastic relaxation, but becomes very important as the stress level increases. At high stress levels, the contribution from the external work done on a lattice cell has to be included in the nonlinear viscoelastic analysis. By taking into account the long range cooperative interaction, the external work can,... 

Ab initio calculations predict a structure with C2 symmetry for the free dini-tramide ion, N(N02)2 (Fig. 10.5), while in solution and in the solid state the local symmetry is essentially C3. This can be explained on the basis of weak cation-anion interactions or interactions with the solvent, since the dinitramide ion is very easy to deform because of the very small barrier to rotation of the NN02 moiety (< 13 kj mob1) [63]. 

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