Impact and Friction

Montan Wax (Lignite wax). White, hard earth wax crude product, dark brown, mp 80—90°. Obtained by countercurrent extrn of lignite. Sol in CCI4, benz chlf insol in w. It is combustible nontoxic. Has been used extensively in Ger for coating particles of expls such as PETN RDX, in order to reduce their sensitivity to impact and friction Ref CondChemDict (1971), 595-R... 

Norris Powder. A low-freezing mining expl invented in 1901 by an American, Norris. It was much less sensitive to impact and friction than contemporary Dynamites. It contained NG 70, mononitrobenzene 15, and Huile empyroma-tique 15%. The latter ingredient consisted of ail oily substance obtained on distn of wood tar. 

Their impact and friction sensitivity data appear to be monotonic functions of corrected OB, but the relation between corrected OB and Trauzl Block data appears to be complex... 

Impact and Friction Initiation of PETN have been extensively studied. This general subject is summarized in Bowden Yoffe (Refs 13 19), Afanas ev Bobolev (Ref 85a), and Vol 7, 135—55, which contains a rather complete description of impact initiation with many refs to the impact and friction initiation of PETN. There is general agreement that impact and friction initiation proceed via a hot spot mechanism (see Vol 7, HI 70—75). There is, however, considerable doubt and controversy about the mechanisms of hot spot formation... 

If an expl is intended for use in primers, then its brisance and power may be lower than for groups (1), (2) and (3), but it should possess low sensitivity to impact and friction and should produce a hot flame in order to ignite a charge of proplnt or a deiay train... 

A similar explanation had already been given for the initiation of explosives by impact and friction. These phenomena have been extensively studied, particularly by Bowden and his school. Their work demonstrated two particularly important modes of initiation ... 

RDX may be used alone in pressed charges, although for this purpose tetryl is a more general choice. For shell and bomb fillings it is too sensitive alone to initiation by impact and friction and is either desensitised with wax, or else used like PETN in admixture with TNT. RDX may also be compounded with mineral jelly and similar materials to give a useful plastic explosive. 

Torpedo friction test. A test of sensitiveness to impact and friction (see p. 70). 

Highly explosive, sensitive to heat, impact and friction (e.g. of a spatula when removing solid from a flask). 

Negyesi, G., Process Safety Progress, 1996,15(1), 42 This compound shows signs of impact and friction sensitivity. 

Hafner, K. etal., Org. Synth., 1964, 44, 102 The crystalline solid is an impact- and friction-sensitive explosive and must be handled with precautions. These include use of solvent-moist material and storage in a corked rather than glass-stoppered vessel. 

Presence of 5% of copper(II) chloride caused explosion to occur at 170°C [1]. Of the series of additives copper chromite, copper chloride, nickel oxide, iron oxide, magnesium oxide, the earlier members have the greatest effect in increasing the sensitivity of the perchlorate to heat, impact and friction. 

The endothermic nitride is susceptible to explosive decomposition on friction, shock or heating above 100°C [1], Explosion is violent if initiated by a detonator [2], Sensitivity toward heat and shock increases with purity. Preparative precautions have been detailed [3], and further improvements in safety procedures and handling described [4], An improved plasma pyrolysis procedure to produce poly (sulfur nitride) films has been described [5], Light crushing of a small sample of impure material (m.p. below 160°C, supposedly of relatively low sensitivity) prior to purification by sublimation led to a violent explosion [6] and a restatement of the need [4] for adequate precautions. Explosive sensitivity tests have shown it to be more sensitive to impact and friction than is lead azide, used in detonators. Spark-sensitivity is, however, relatively low [7],... 

Test results ( , ) for several candidate materiaIs (Table III) are reported which span the range of energetic capacity. Those values which exceed the threshold are highly susoect and have been known to result in serious fires in the past. Mix No. 1, (M49A1, Trip Flare Mixture) is a "safe" mixture that is insensitive to electrical spark, impact, and friction. It does not have a fast bum rate on the Vee Block tester and it has a low pressure-rate-of-rise. 

A substance or mixture is potentially capable of deflagration if it has a AHd greater than 250 cal/g (-1000 J/g), a "yes" in Box 8. Deflagration tests (Box 7) then should be carried out as well as tests for sensitivity to impact and friction. 

The thermochemical evaluation of the reactants is the place to start, as discussed in Chapter 2. If the potential energy release is 250 cal/g of substance (1000 J/g) or more, it is necessary to determine initiation properties, such as a sensitivity to impact and friction. Thermochemical evaluation of reaction... 

Mercury fulminate (C2N202Hg) is one of the most important primary explosives. It is usually found in the form of a gray powder, is sensitive to impact and friction, and is easily detonated by sparks and flames. It is desensitized by the addition of water, but is very sensitive to sunlight. It reacts with metals in moist environments. It is created by treating a solution of mercuric nitrate with alcohol in nitric acid. Its most important explosive property is that it easily detonates after initiation.10... 

Addition of liquid air to ether in a dish caused a violent explosion after a short delay. Previous demonstrations had been uneventful, though it was known that such mixtures were impact- and friction-sensitive. 

Oxidative nitration avoids the isolation of em-nitronitronate salts, which are often unstable explosives with a high sensitivity to impact and friction. 

The sensitivity of an explosive to impact and friction is a key factor in deciding whether it finds practical use. Most developed countries have an ongoing program to gradually replace current explosives and propellants with insensitive materials, a process which will greatly reduce the risk of accidental detonation. At present these programs are still in their early phases. 

Similarly, 5-picrylamino-l,2,3,4-tetrazole (PAT) (116) " " and 5,5 -styphnylamino-1,2,3,4-tetrazole (SAT) (117) " have been synthesized by condensing picryl chloride and styphnyl chloride with 5-amino-l,2,3,4-tetrazole in methanol respectively. A comparison of thermal and explosive properties of newly synthesized PAT (calculated VOD 8126 m/s) and SAT (calculated VOD 8602 m/s) reveals that PAT is more thermally stable than SAT but more sensitive to impact and friction. " ... 

The energetic nature of the N-NO2 group means that At-nitro-based explosives are some of the most powerful explosives available and these have largely superseded aromatic C-nitro compounds for military applications. Many nitramines exhibit high brisance and high chemical stability in combination with a favourable low sensitivity to impact and friction compared to nitrate ester explosives of similar power. 

The reaction is complete in several hours and, in liquid NHs, it is greatly accelerated by NaNHs (186,187). From the ammonium perchloryl amide, which could not be isolated in pure form, the corresponding Ag+, Cs", and K" " salts and K2NCIO3 and CS2NCIO3 have been obtained. These salts, especially when dry, are impact- and friction-sensitive. 

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