Cryochemical reactions

It should be noted that in the initiation of the cryochemical reactions observed, what is important is the very fact of formation of a new crack (or zone cut by such cracks), and not the increase in the specific internal surface of the sample. Indeed, slow heating of a monolithic sample, or of a sample... 

The extensively studied (especially during the recent years) transitions of solids from the metastable amorphous state to the polycrystalline state (see ref. 58 and the references therein) are of autowave character and resemble very much the above regimes of solid-state cryochemical reactions. The action of autodispersion, which facilitates phase transition by allowing it to proceed on the surface of a fracture instead of in the glass volume, cannot be excluded in the case of those processes either. Actually, the two classes of processes are similar in their physical nature both are connected with rearrangement of the solid matrix and are of exothermic character, differing only in the extent of the thermal effect. It should be added that fracturing and autodispersion of the sample are very typical of the autowave destruction of amorphous states and can be seen even by the unaided eye. 

Benderskii, V., Goldanskii, V. and Makarov, D. (1990). The theory of cryochemical reaction rates in the Leggett formalism. Chem. Phys. Lett. 171, 91-96... 

We emphasize that only brittle disruption was capable to ignite the reaction. A fast interaction of the needle with the san )le, involving time scales of order 0.01-0.1 s is necessary to induce the effect. This is reminiscent of what happens in shock waves. If the m hanical loading of the needle is much slower (times scale of the order of 1 ms), the reaction is not ignited. It means that a plastic deformation is not capable to excite the reactions, and, as suggested by theory, only elastic deformations and following brittle disruption is a necessary condition for cold ignition of cryochemical reactions in solids. 

Most of these features of cryochemical reactions are also of great significance for cryotropic gelation processes [8]. Moreover, if the system contains polymeric solutes, the stiU-liquid fraction can exist even at rather low temperatures and such... 

Kiryukhin, D.P., Barelko, V.V., and Barkalov, l.M. (1999) Traveling waves of cryochemical reaction in radiolyzed systems (review). High Energ. Chem.,... 

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