Explosive Properties

1. Explosive Properties Explosives 189 Dr. Van Romero 26 Jan 2012

2. Proximity Fuse

4. Some Definitions • Explosion – rapid expansion of matter into a volume much greater than the original volume

5. Some Definitions • Explosion – rapid expansion of matter into a volume much greater than the original volume • Burn & Detonate – Both involve oxidation • Burn – relatively slow • Detonate – burning at a supersonic rate producing a pressure Wave

6. Some Definitions • Explosion – rapid expansion of matter into a volume much greater than the original volume • Burn & Detonate – Both involve oxidation • Burn – relatively slow • Detonate – burning at a supersonic rate producing a pressure Wave • Deflagration – Burning to detonation (DDT)

7. Some Definitions • Explosion – rapid expansion of matter into a volume much greater than the original volume • Burn & Detonate – Both involve oxidation • Burn – relatively slow • Detonate – burning at a supersonic rate producing a pressure Wave • Deflagration – Burning to detonation (DDT) • Shock wave – High pressure wave that travels faster then the speed of sound

8. Explosives Vs. Propellants • The difference between an explosive and a propellant is functional as apposed to fundamental.

9. Explosives Vs. Propellants • The difference between an explosive and a propellant is functional as apposed to fundamental. • Explosives are intended to function by detonation from shock initiation(High Explosives)

10. Explosives Vs. Propellants • Propellants are initiated by burning and then burn at a steady rate determined by the devise, i.e. gun (Low Explosives) • Single molecule explosives are categorized by the required initiation strength

11. Primary Explosives • Primary Explosives – Transit from surface burning to detonation within a very small distance. • Lead Azide (PbN6 )

12. Secondary Explosives • Secondary Explosives – Can burn to detonation, but only in relatively largequantities. Secondary explosives are usually initiated from the shock from a primary explosive (cap sensitive) •  TNT

13. Tertiary Explosives • Tertiary Explosives – Extremely difficult to initiate. It takes a significant shock (i.e. secondary explosive) to initiate. Tertiary explosives are often classified as non-explosives. • Ammonium Nitrate (NH4NO3)

14. Exothermic and Endothermic Reactions • Chemical reaction • Reactants  Products. • Internal energy of reactants ≠ internal energy of products. • Internal energy: contained in bonds between atoms. • Reactants contain more energy than products—energy is released as heat. • EXOTHERMIC Reaction.

15. Exothermic and Endothermic Reactions • Products contain more internal energy than reactants • ENDOTHERMIC Reaction • Energy must be added for the reaction to occur. • Burning and detonation are

16. Exothermic and Endothermic Reactions • Products contain more internal energy than reactants • ENDOTHERMIC Reaction • Energy must be added for the reaction to occur. • Burning and detonation are Exothermic

17. Oxidation: Combustion • Fuel + Oxidizer Products (propellant)

18. Oxidation: Combustion • Fuel + Oxidizer Products (propellant) • CH4 + 2 O2 CO2 + 2 H20 Methane Oxygen Carbon Dioxide Water

19. Oxidation: Combustion • Fuel + Oxidizer Products (propellant) • CH4 + 2 O2 CO2 + 2 H20 • Oxidation (combustion) of methane • 1 methane molecule : 2 oxygen molecules (4 oxygen atoms). Methane Oxygen Carbon Dioxide Water

20. Oxidation: Decomposition • Oxidizer + Fuel  decomposition to products (Explosive)

21. Oxidation: Decomposition • Oxidizer + Fuel  decomposition to products (Explosive) • Example: Nitroglycol • O2N—O—CH2—CH2—O—NO2 Fuel (Hydrocarbon)+ Oxidizer (Nitrate Esters)

22. Oxidation: Decomposition • Oxidizer + Fuel  decomposition to products (Explosive) • Example: Nitroglycol • O2N—O—CH2—CH2—O—NO2 • Undergoes Decomposition to: 2 CO2 + 2 H2O + N2 Fuel (Hydrocarbon)+ Oxidizer (Nitrate Esters) Carbon Dioxide Water Nitrogen

23. CHNO Explosives • Many explosives and propellants are composed of: • Carbon • Hydrogen • Nitrogen • Oxygen • General Formula: CcHhNnOo • c, h, n, o are # of carbon, hydrogen, nitrogen and oxygen atoms. • For Nitroglycol: C2H4N2O6

24. CHNO Explosive Decomposition • CcHhNnOoc C + h H + n N + o O • Imagine an explosive detonating. • Reactant CHNO molecule is completely broken down into individual component atoms.

25. CHNO Explosive Decomposition • CcHhNnOoc C + h H + n N + o O • Imagine an explosive detonating. • Reactant CHNO molecule is completely broken down into individual component atoms. • For Nitroglycol: • 2N  N2 • 2H + O  H20 • C + O  CO • CO + O  CO2

26. OveroxidationvsUnderoxidation • In the case of nitroglycol • O2N—O—CH2—CH2—O—NO2 2 CO2 + 2 H2O + N2 • Exactly enough oxygen to burn all carbon to CO2 • Some have more than enough oxygen to burn all the carbon into CO2 • OVEROXIDIZED OR FUEL LEAN • Most explosives do not have enough oxygen to burn all the carbon to CO2 • UNDEROXIDIZED OR FUEL RICH

27. Simple Product Hierarchy for CHNO Explosives • First, all nitrogen forms N2

28. Simple Product Hierarchy for CHNO Explosives • First, all nitrogen forms N2 • Then, all the hydrogen is burned to H2O

29. Simple Product Hierarchy for CHNO Explosives • First, all nitrogen forms N2 • Then, all the hydrogen is burned to H2O • Any oxygen left after H20 formation burns carbon to CO.

30. Simple Product Hierarchy for CHNO Explosives • First, all nitrogen forms N2 • Then, all the hydrogen is burned to H2O • Any oxygen left after H20 formation burns carbon to CO. • Any oxygen left after CO formation burns CO to CO2

31. Simple Product Hierarchy for CHNO Explosives • First, all nitrogen forms N2 • Then, all the hydrogen is burned to H2O • Any oxygen left after H20 formation burns carbon to CO. • Any oxygen left after CO formation burns CO to CO2 • Any oxygen left after CO2 formation forms O2

32. Simple Product Hierarchy for CHNO Explosives • First, all nitrogen forms N2 • Then, all the hydrogen is burned to H2O • Any oxygen left after H20 formation burns carbon to CO. • Any oxygen left after CO formation burns CO to CO2 • Any oxygen left after CO2 formation forms O2 • Traces of NOx (mixed oxides of nitrogen) are always formed.

33. Decomposition of Nitroglycerine • C3H5N3O9  3C + 5H + 3N + 9O • 3N  1.5 N2 • 5H + 2.5O  2.5 H2O (6.5 O remaining) • 3C + 3O 3 CO (3.5 O remaining) • 3 CO 3O  3 CO2 (0.5 O remaining) • 8.5 of 9 oxygen atoms consumed • 0.5 O  0.25 O2

34. Decomposition of Nitroglycerine • C3H5N3O9  3C + 5H + 3N + 9O • 3N  1.5 N2 • 5H + 2.5O  2.5 H2O (6.5 O remaining) • 3C + 3O 3 CO (3.5 O remaining) • 3 CO + 3O  3 CO2 (0.5 O remaining) • 8.5 of 9 oxygen atoms consumed • 0.5 O  0.25 O2 • Overall Reaction: • C3H5N3O9 1.5 N2 + 2.5 H2O + 3 CO2 + 0.25 O2 • Oxygen Remaining = Nitroglycerine is • OVEROXIDIZED

35. Decomposition of RDX H2 • C3H6N6O6 3C + 6H +6N +6O • 6N  3N2 • 6H + 3O  3H2O (3 O remaining) • 3C + 3O  3CO (All O is consumed) • No CO2 formed. H2 H2

36. Decomposition of RDX H2 • C3H6N6O6 3C + 6H +6N +6O • 6N  3N2 • 6H + 3O  3H2O (3 O remaining) • 3C + 3O  3CO (All O is consumed) • No CO2 formed. • Overall Reaction: • C3H6N6O6 3 N2 + 3 H2O + 3 CO • Not enough oxygen to completely burn all of the fuel • UNDEROXIDIZED H2 H2

37. Oxygen Balance • OB (%) • 1600/MWexp[oxygen-(2 carbon+ hydrogen/2)] • Oxygen balance for Nitroglycol C2H4N2O6 • c = 2, h = 4, n = 2, o = 6 • Mwexp=12.01 (2) + 1.008 (4) + 14.008 (2) + 16.000 ( 6) = 152.068 g/mol • OB = = 0% 1600 4 6 – 2 (2) – 152.068 2 Perfectly Balanced

38. Oxygen Balance • Oxygen balance for Nitroglycerine C3H5N3O9 • C = 3, h = 5, n = 3, o = 9 • Mwexp=12.01 (3) + 1.008 (5) + 14.008 (3) + 16.000 ( 9) = 227.094 g/mol • OB = = 3.52% 1600 5 9 – 2 ( 3) – 227.094 2 Slightly overoxidized

39. Oxygen Balance • Oxygen balance for RDX: C3H6N6O6 • C = 3, h = 6, n = 6, o = 6 • Mwexp=12.01 (3) + 1.008 (6) + 14.008 (6) + 16.000 ( 6) = 222.126 g/mol • OB = = -21.61% 1600 6 6 – 2 ( 3) – 222.126 2 Underoxidized

40. Homework • Calculate the oxygen balance for: • TNT • Picric Acid