MSE 404 Presentation 12-7

Report
Erin Morris
Mining Engineering
Outline
 What I do
 Why I’m here
 Basics of Explosives
 Definitions
 Classifications
 Initiation & Sensitivity
 Insensitive Munitions
 Polymers in Explosives
 Binders
 Plasticizers
 Special Uses
What I do
 Master’s in Mining Engineering
 Emphasis in Explosives
What is a Mining Engineer
Doing Here?
• Explosives Engineering is a combination of
many other sciences and engineering
technologies: (Cooper)
 Chemistry
 Materials
 Thermodynamics
 Electricity and Electronics
 Fluid Dynamics
 Meteorology
 Aerodynamics
 Biology
 Mechanics
 Physiology
The Basics
 Explosive:
 “A substance which can be initiated by friction, impact,
shock, spark, flame, heating or simple application of an
energy pulse; and undergoes a rapid chemical reaction
evolving a large amount of heat and exerting a high
pressure on its surroundings.” (Agrawal and Hodgson)
 An explosion will either produce a shock wave, throw
fragments, or both
www.youtube.com/watch?v=2imofil5GbM&feature=related
Definitions
 Deflagration vs. Detonation
 Deflagration is a thermal decomposition (burning)
 Detonation is thermal decomposition completed at
shock velocities (burning + shock)
 Brisance:
 Speed at which reaction occurs
 Shattering potential of an explosive
 Depends on explosive composition and degree of
confinement of the blast
Classifications
 Low Explosives
 Slow reaction with a gradual, extended shock wave and
low fragment velocities
 Low brisance; releases a large amount of energy, but
long duration allows energy to dissipate
 Expansion of the gases used to move
projectiles (Propellants)
Classifications
 High Explosives
 Violent reaction with a short duration, high pressure
shock wave and large fragment velocities
 High brisance; used solely for destructive power
High Explosives
Trinitrotoluene
(TNT)
Cyclo-1,3,5-trimethylene2,4,6-trinitramine
(RDX)
Pentaerythritol tetranitrate
(PETN)
Initiation & Sensitivity
 Primary Explosives
 Very sensitive to heat, impact, friction or static
electricity; easily detonated
 Used in blasting caps to trigger larger secondary charges
 Secondary Explosives
 Less sensitive; requires more energy (primary explosive)
to be detonated
 Used in large quantities, more powerful than primary
explosives
Insensitive Munitions
 Two goals in design of future explosives
 Increase performance
 Decrease hazards during transport and storage
 Many ways to accomplish this
 New designs
 Packaging and mitigation devices
 Make explosives less sensitive to accidental initiation
Polymers in Explosives
 Functions:
 Binders
 Plasticizers
 Products:
 Rocket Propellants
 Plastic-Bonded Explosives (PBXs)
 Putties, Rubberized & Extrudable Explosives
 Can be inert or energetic
Binders
 Some consider dynamite as the first use of binders in
explosives
 Alfred Nobel absorbed nitroglycerin into a porous
medium (diatomaceous earth) to reduce its sensitivity
and allow for safe handling
 Modern dynamites use a variety of absorbents and
additives
PBXs
 Today cross-linked polymers are used to provide a
matrix to bind explosives to other components
 Plastic-Bonded Explosives (PBXs)
 Polymeric binder coats and suspends the crystals of a
powdered explosive
 Mixture cured to create a tough elastomer which can
absorb and dissipate energy from friction and shock
 Combined with plasticizers, allows PBXs to be pressed
and machined
Common PBXs
Binders in PBXs
Plasticizers
 Plasticizers are mixed with finely powdered explosives
to create putties
 Putties can be molded into almost any shape by hand,
and retains its shape unsupported after molding
 The most common putty explosive in the United States
is Composition C-4
Composition C-4
“Special” Uses
 Rubberized Explosives
 Mix of RDX or PETN with plasticizers and rubber-type
polymers that can be rolled into thin sheets
 Sheets can be cut to shape, bent, and glued to surfaces
DOE LX-02-1 Composition
“Special” Uses
 Extrudable Explosives
 RDX or PETN mixed with Sylgard 182 silicone rubber
and curing agent, forms a thick viscous material that can
be extruded
 After extrusion, temperature can be raised to polymerize
and cure the Sylgard
 Another version from North American Explosives is
packaged in small tubes to fit a standard caulking gun
Key Point to Remember
 Name the 2 functions of polymers used in explosives
and describe how they work in plastic-bonded
explosives (PBXs).
 Binder
 Plasticizer
 In plastic-bonded explosives (PBXs), a binder coats and
suspends the crystals of a powdered explosive. This
mixture is cured to create a tough elastomer which can
absorb and dissipate energy from friction and shock.
References
 Agrawal, J.P., and Hodgson, R.D. 2007. Organic
Chemistry of Explosives. John Wiley & Sons, Ltd.
Chichester, West Sussex, England.
 Baird, J. 2010. Class notes, unknown author.
 Cooper, P. W. 1996. Explosives Engineering. WileyVCH Inc. New York, NY, USA.
 Provatas, A. 2000. “Energetic Polymers and Plasticisers
for Explosive Formulations – A Review of Recent
Advances.” DSTO, Aeronautical and Maritime
Research Laboratory. Melbourne, Victoria, Australia.
 www.youtube.com/watch?v=2imofil5GbM&feature=related

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