Hotspots formation mechanisms

The formation of hotspots depends upon the energy input and the physical properties of the explosive composition. The diameter of the hotspots is in the region of 0.1-10 fim and their duration is about HTMO-3 s with temperatures greater than 900 °C. There have been various theories put forward to describe the mechanisms for the formation of hotspots, some of which are described below. 

Much of the work done in recent years on polymer mechanochemistry has made use of the high elongational strain rates observed around collapsing cavitation bubbles in sonicated solutions, as outlined in the section on mechanoluminescence [27]. In addition to the distinctive features of sonochemically-induced mechanical reactivity described above, further attention needs to be paid to the sonication conditions in the case of mechanochemical catalysis, because catalyst lifetime and turnover number are reduced by sonochemical byproducts. Implosion of cavitation bubbles is essentially an adiabatic process which leads to formation of local hotspots within the bubble in which temperature and pressure increases drastically. The content of cavitation bubbles pyrolyses under these extreme conditions and results in formation of reactive species, such as radicals and persistent secondary byproducts acidic byproducts may also form from the degradation of the substrates [75]. Chemical impurities deactivate the reactive catalyst partially if not completely. Recent studies in our group have shown that heat capacity of gas... 

D. Tabor (Cambridge University) Could the speaker comment on the mechanism by which polymer formation occurs Does it arise from known processes such as the exposure of fresh surface, local hotspots high local pressures, etc., or must one invoke a new process and coin another Greek word like Tribochemistry to cover our i gnoraace. 

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