ThiokolPropulsion

The Promise Of Energetic TPEGun Propellants – From Notebook

To Full Scale Verification

The Promise Of Energetic TPEGun Propellants – From Notebook

To Full Scale Verification

Prepared For:

NDIA 37th Annual Gun And Ammunition SymposiumPanama City, Florida

April 15-18, 2002

P. Braithwaite, G. Dixon, M. Rose, and R. Wardle

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Acknowledgements

• Advances in these new propellants are theresults of cooperative efforts with manyorganizations including:• ARL• TACOM-ARDEC• DTRA• NSWC/IH• ONR• GD• SAIC• United Defense

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Outline

• Background

• Typical ETPE propellant ingredients

• Propellant processing

• Propellant characterization

• Gun testing

• Summary and conclusions

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Background

• The potential advantages of TPE gun propellantswere seriously discussed in the early 1980’s

• Performance• Environmental benefits - R3• Superior burning rate control

• No plasticizers are used

• No sensitivity to moisture

• Early feasibility studies were successfullyperformed in coordination with ARL/ONR and others• Identified areas of critical technical needs• Developed initial data to verify attractiveness

• Recent efforts have demonstrated these propellantson a larger scale

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Background (cont.)• Early calculations using ETPE propellant formulations

indicated they had performance advantages whencompared with NC based compositions

Impetus vs Flame Temperature

2000

2500

3000

3500

4000

900 1000 1100 1200 1300 1400

Impetus (J/g)

Flam

e T

empe

ratu

re (K

)NC/NEPropellants

Advanced TPEPropellants

• Burning ratetailorabilitysuggested byearly low pressuretests indicatedthese propellantscould be used inconventional andlayeredgeometries

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Oxetane Thermoplastic Elastomers

Below Tm of Hard BlockHard Block Crystalline Sphereulites

Soft Block Elastomers

Above Tm of Hard BlockHard Block Melts

Blocks phase separated

Flows and Mixes under ShearHard and Soft Blocks Mix

Annealing needed for phase separation

15010050010 4

10 5

10 6

10 7

10 8

10 9

Temperature (C)

Eta

(poi

se)

• Melting materials behavior critical to energetic processing• need narrow transition from hard to processible• m.p. too low and won't survive environment (<65°C)• m.p. too high and energetic solids can't beprocessed safely (>90°C)• dynamic viscosity data show attractiveness ofcrystalline hard block oxetane TPE (green line)

• Novel TPEs allow continuous processing and recycling• production scrap can be well below 1 percent

• TPE nature allows unusual geometries• better energy management maximizes performance

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TPE’s Offer Formulation Flexibility

C CH 2H2CHO O

CH 2N3

CH 2N3

CH 2 C

CH 2N3

CH 2N3

CH 2 O CH 2 C CH 2

CH 2N3

CH 3

O H

BAMO/BAMO-AMMO

x y

C CH 2H2CHO O

CH 2N3

CH 2N3

CH 2 C

CH 2N3

CH 3

CH 2 O

x

BAMO/AMMO

H

y

C CH 2H2CHO O

CH 2OEt

CH 2OEt

CH 2 C

CH 2N3

CH 3

CH 2 O

x

BEMO/AMMO

H

y

C CH 2H2CHO O

CH 2N3

CH 2N3

CH 2 C

CH 2ONO 2

CH 3

CH 2 O

x

BAMO/NMMO

H

y

x y

most energetic

least energetic

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TEX

New Energetic Solids

• Energetic solids provide additional burning rate andenergy tailoring capability

CL-20

• Burning rates at 40 kpsi fromless than 4 in/sec to over 15in/sec

• Impetus levels above 1350 J/g

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Twin Screw Extrusion

• Twin screw extrusion hasbeen found to be the bestway to mix and extrudepilot scale lots of ETPEbased propellants

• No solvents are requiredduring mixing andextrusion

• Multiple formulations havebeen extruded into a widerange of geometries

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Multiple Geometries Have BeenSuccessfully Manufactured

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SEM Evaluation• Careful examination indicates excellent adhesion

between solid ingredients and ETPE

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Gun Testing

• ETPE propellants have been tested inmultiple gun systems• 30 mm

• 35 mm

• 40 mm

• 60 mm

• 120 mm

• 5-inch

• 155 mm

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120 mm Firings

• ETPE propellantshave been tested in120 mm gunsystems usingadvancedgeometries

• Results were great!!!

PA0PA270PB0PB90PB180PB270PC0

Advanced TPE

Propellant

PA0PA270PB0PB90PB180PB270PC0

Current Perforated Propellant

Pre

ssu

reP

ress

ure

Time

Time

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Summary

• ETPE propellants have matured significantly duringthe past several years• Formulation• Processing• Testing and characterization• Quality control• Recycle and reclamation• Grain design

• Multiple gun test firings unequivocallydemonstrated the performance potential of thesepromising new propellants