Self-accelerating

INFRAREDTECHNOLOGYANDRAMANSPECTHOSCOPY-INFRAREDTECHNOLOGY] (Vol 14) SADT. See Self accelerating decomposition temperature. 

As a consequence of their susceptibility to radical-induced decomposition, neat and concentrated solutions of diacyl peroxides undergo self-accelerating... 

The use of monomers that do not homopolymerize, eg, maleic anhydride and dialkyl maleates, reduces the shock sensitivity of tert-huty peroxyesters and other organic peroxides, presumably by acting as radical scavengers, that prevent self-accelerating, induced decomposition (246). 

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test Explosion propagation with detonation Drop weight test Thermal decomposition test Influence test Self-acceleration temperature Card gap test (under confinement) JANAE Critical diameter Pyrophoricity... 

Since the early days of using PVC separators in stationary batteries, there has been a discussion about the generation of harmful substances caused by elevated temperatures or other catalytic influences, a release of chloride ions could occur which, oxidized to perchlorate ions, form soluble lead salts resulting in enhanced positive grid corrosion. Since this effect proceeds by self-acceleration, the surrounding conditions such as temperature and the proneness of alloys to corrosion as well as the quality of the PVC have to be taken carefully into account. 

Thus, the process of PAN transformation under the effect of IR radiation proceeds with considerable self-acceleration. The irradiation of uniaxially oriented PAN films gives a polymer with a distinct anisotropy of optical properties, dichroism in the visible spectral region in particular. Figure 8 presents dichroism curves [D =/(X)] at various angles (ip) between the polarization plane and the orientation axis. The same figure shows the dependence D =f(uniaxially oriented film. 

Performic acid solns are unstable and undergo a self-accelerating exothermic decompn at ambient temp (Ref 2). An 80% soln expld at 80— 85° (Ref 1). A small sample of the pure vacuum distd material cooled to below —10° expld violently when the flask was moved (Ref 5). Although the acid has occasionally been distd, it... 

Self-acceleration temperature Card gap test (under confinement) lANAF... 

Succinonitrile that is kept at a temperature of 80°C for forty six hours caused a violent decomposition, after being heated to 195°C to eliminate some compound solidified in a pipe. Differential thermal analysis showed that the reaction was self-accelerated with a period of induction of thirty three hours at 200°C and an hour and a half at 280 C. No heat was given off during the period of induction. Once started, the decomposition is very fast and there is no inhibitor. The cyanide ion shortens the period of induction. 

An 850 kg batch of a slightly doped form of azodicarbonamide exploded violently, with a TNT equivalence of 3.3 kg, 5 minutes after sampling at the end of drying. The probable initial temperature was 65°C, the lowest self accelerating decomposition temperature 90°C, and such decomposition is not explosive. Full explosibility tests, including detonability, had shown no hazard. Further study demonstrated that slightly contained azodicarboxamide, thermally initiated at the bottom of a column or conical vessel could explode even at the 5 kg scale. The above TNT equivalence corresponds to decomposition of 4% of the available charge. The cause of the presumptive hot spot is unknown. 

See other induction period incidents, self-accelerating reactions Acid anhydrides... 

Of the factors associated with the high reactivity of cyanuric chloride (high exother-micity, rapid hydrolysis in presence of water-containing solvents, acid catalysed reactions, liberation of up to 3 mol hydrogen chloride/mol of chloride, formation of methyl chloride gas with methanol, formation of carbon dioxide from bicarbonates), several were involved in many of the incidents recorded [1] (and given below). The acid catalysed self acceleration and high exothermicity are rated highest [2]. It is also a mildly endothermic compound (AH°f (s) +91.6 kJ/mol, 0.49 kJ/g). 

An attempt to chlorinate xylene with the dichlorohy dantoin caused a violent explosion [1], The haloimide undergoes immediate self accelerating decomposition in presence of solvents. Safe conditions (including lower temperatures and progressive addition of reagent to match its consumption) can be developed for its use [2],... 

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