Secondary impact sensitivity

It is significant, however, that in most, and probably all, relative rankings of the impact sensitivities of solid expls (see Vol 7, I42-R), PETN ranks as the most sensitive secondary expl (primary expls, such as Lead Azides, Mercuric Fulminate, etc, are more sensitive)... 

In contrast, secondary nitramines have no acidic hydrogen and often exhibit a high chemical stability in combination with acceptable thermal and impact sensitivity. Consequently, secondary nitramines are often the explosives of choice for military use. 

Secondary high explosive Secondary high explosive Impact-sensitive material Blood agent, Extreme poison Binder, Color enhancer Low explosive, Found in many types of pyrotechnics, flash/concussion grenades, flash bangs, and fireworks... 

Primary high explosive, Extremely press ure/impact sensitive Secondary high explosive. Main charge in many military munitions... 

Primary high explosive. Impact sensitive material Secondary high explosive, Used in some forms of dynamite... 

Impact-sensitive material Secondary high explosive... 

The impact sensitivity of some well-known primary, secondary and tertiary explosives is given in the Table 1.3. 

On the other hand, Dudek et al. found that the impact sensitivity (h50% ) of e CL-20 28 cm is comparable to that of [5-HMX (h50% = 30 cm) [124]. Agrawal et al. have not only given impact sensitivity of CL-20 but also the mechanism of initiation on impact leading to its detonation. This is in line with the mechanism of initiation by hot spot formation on impact followed by detonation similar to other secondary explosives [125]. 

It is thus not surprising that, even neglecting differences in apparatus, data that relate the impact sensitivities of explosives are generally not consistent, a comment which applies even to the sensitivity of lead azide relative to that of secondary explosives. For example, there exist data by Kondrikov [30] showing that in a comparatively well-instrumented apparatus lead azide appeared less sensitive to impact than TNT, PETN, and TNB. Tables II and III illustrate the degrees of consistency obtainable with present apparatus. 

ColMSAT and PAC are known to have short DDT distances. The impact sensitivity of PAC determined by GOST-4545-88 (2 kg hammer, impact height 25 cm) is 16 %. The initiation efficiency for RDX is 0.4 g the calculated detonation velocity is 6.98 km s for density 1.82 g cm . This clearly indicates that the complex is a primary explosive (with relatively low initiation efficiency) but with sensitivity to mechanical stimuli comparable to secondary explosives [26]. 

Ethylenedinitramine (EDNA) is a powerful secondary explosive patented by Hale [3]. The two acidic hydrogens of the nitramino group can be relatively easily replaced with metal ions. Every once in a while speculation arises regarding the applicability of EDNA salts for use as primary explosives. The sensitivity of the metallic salts is, however, relatively low. The cupric salt of ethylenedinitramine is less sensitive than both LA and LS. It follows from Table 13.2 that it is comparable to secondary explosives. Ignition of CuEDNA occurs at 196 °C, DSC onset is at 162 °C (10 °C min ) [4]. Cupric, ferrous, lead, and potassium salts of EDNA are more sensitive then RDX but not sensitive enough to qualify for use as primary explosives. Impact sensitivities obtained by Blatt [5] and summarized in Fedoroff, Shefield, and Kaye s [6] are listed in Table 13.3. 

As hydrazine is an endothermic compound that decomposes exothermically, its derivatives and metal complexes are also highly unstable and some of them fall into the category of high energy materials (HEMs). For such HEMs it becomes essential to test their properties by friction and impact sensitivity tests along with standard techniques like TG/DTA or DSC. This allows for differentiation between HEMs that are classified as primary that is, very sensitive materials which easily explode by the application of fire, spark, impact, friction, and so on, and HEMs that are classified as secondary, that is, materials that are relatively insensitive to both mechanical shock and flame but explode with greater violence when set off [38],... 

Explosives are commonly categorized as primary, secondary, or high explosives. Primary or initiator explosives are the most sensitive to heat, friction, impact, shock, and electrostatic energy. These have been studied in considerable detail because of the almost unique capabiUty, even when present in small quantities, to rapidly transform a low energy stimulus into a high intensity shock wave. 

The impact of an ion beam on the electrode surface can result in the transfer of the kinetic energy of the ions to the surface atoms and their release into the vacuum as a wide range of species—atoms, molecules, ions, atomic aggregates (clusters), and molecular fragments. This is the effect of ion sputtering. The SIMS secondary ion mass spectrometry) method deals with the mass spectrometry of sputtered ions. The SIMS method has high analytical sensitivity and, in contrast to other methods of surface analysis, permits a study of isotopes. In materials science, the SIMS method is the third most often used method of surface analysis (after AES and XPS) it has so far been used only rarely in electrochemistry. 

By employing a laser for the photoionization (not to be confused with laser desorption/ ionization, where a laser is irradiating a surface, see Section 2.1.21) both sensitivity and selectivity are considerably enhanced. In 1970 the first mass spectrometric analysis of laser photoionized molecular species, namely H2, was performed [54]. Two years later selective two-step photoionization was used to ionize mbidium [55]. Multiphoton ionization mass spectrometry (MPI-MS) was demonstrated in the late 1970s [56—58]. The combination of tunable lasers and MS into a multidimensional analysis tool proved to be a very useful way to investigate excitation and dissociation processes, as well as to obtain mass spectrometric data [59-62]. Because of the pulsed nature of most MPI sources TOF analyzers are preferred, but in combination with continuous wave lasers quadrupole analyzers have been utilized [63]. MPI is performed on species already in the gas phase. The analyte delivery system depends on the application and can be, for example, a GC interface, thermal evaporation from a surface, secondary neutrals from a particle impact event (see Section 2.1.18), or molecular beams that are introduced through a spray interface. There is a multitude of different source geometries. 

Lead azide (PbN6) is a colorless to white crystalline explosive. It is widely used in detonators because of its high capacity for initiating secondary explosives to detonation. However, since lead azide is not particularly susceptible to initiation by impact, it is not used alone in initiator components. It is used in combination with lead styphnate and aluminum for military detonators, and is used often in a mixture with tetrazene. It is compatible with most explosives and priming mixture ingredients. Contact with copper must be avoided because it leads to formation of extremely sensitive copper azide. 

Pentaerythritol tetranitrate (PETN) is a colorless crystalline solid that is very sensitive to initiation by a primary explosive. It is a powerful secondary explosive that has a great shattering effect. It is used in commercial blasting caps, detonation cords, and boosters. PETN is not used in its pure form because it is too sensitive to friction and impact. It is usually mixed with plasticized nitrocellulose or with synthetic rubbers to form PBXs. The most common form of explosive composition containing PETN is Pentolite, a mixture of 20 to 50% PETN and TNT. PETN can be incorporated into gelatinous industrial explosives. The military has in most cases replaced PETN with RDX because RDX is more thermally stable and has a longer shelf life. PETN is insoluble in water, sparingly soluble in alcohol, ether, and benzene, and soluble in acetone and methyl acetate. 

The first move in this direction was to improve the weatherability of impact-resistant polystyrene. Because polybutadiene, the most widely used rubber in impact-resistant polystyrene, is unsaturated, it is sensitive to photooxidation, and impact-resistant polystyrene is therefore not suitable for outdoor applications. A saturated rubber might be able to help here. In the ABS sector this has been successfully tried out with acrylate rubber (77) and EPDM (78, 79), and the latter has also been used in impact-resistant polystyrene (80, 81) This development has elicited satisfactory responses only in certain areas and more work still has to be done. For instance, attempts have been made to improve resistance to weathering by using silicone rubber (82 ). This approach is effective, but economic factors still stand in its way. Further impetus may also be expected from stabilizer research. Hindered secondary amines (83), to which considerable attention has recently been paid, are a first step in this direction. 

The chemical properties of primary and secondary nitramines are important in relation to their use as explosives. Primary nitramines contain acidic hydrogen in the form of —N//NO2 and, consequently, in the presence of moisture, primary nitramines corrode metals and form metal salts, some of which are primary explosives. This is one reason why powerful explosives like methyinitramine (1) have not found practical use. Ethylenedinitramine (EDNA) (2) suffers from similar problems but its high brisance (VOD 8240 m/s, d = 1.66 g/cm ) and low sensitivity to impact have seen it used for some applications. 

Laval and Vignane reported the synthesis of the nitrotriazole (124) from the reaction of 3-nitro-1,2,4-triazole with 3,5-diamino-l-chloro-2,4,6-trinitrobenzene. The nitrotriazole (124) is a useful secondary high explosive, exhibiting high performance and a low sensitivity to impact. 

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