MSE 404 Presentation 12-7
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Transcript MSE 404 Presentation 12-7
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