IHDIV, NSWC's Rheological Capabilities Suzanne E. Prickett Bill Newton IHDIV NSWC PDCS TSE User's Group Meeting October 30 th, 2002

Rheology The Study of Flow and Deformation of Materials Yield Stress Viscoplasticisity Shear Rate Wall Slip Activation Energy Hershel Bulkley Constitutive Equation –(  w =  o + m o  w n ) Necessary for Die Design and Modeling

IHDIV NSWC Rheological Capabilities Capillary Dies Used in Conjunction with the 2" Vertical Press (~7 years) Slit Die Rheometer Used with 40 mm Twin Screw Extruder (redesigned last year) Torque Rheometer (~5 years) Small Scale Capillary Rheometer (~1 year – not yet approved for use with energetics)

Capillary Dies w/2" Press Dies and Press Jacketed for Temperature Control (ambient to 270ºF) Automated Data Acquisition System Dies Instrumented with Dynisco Temperature/Pressure Transducer at Capillary Entrance Need ~ 4 – 10 Pounds of Material to Fully Characterize Rheological Behavior Characterized ~ 10 Types of Energetic Materials as a Function of Temperature, Solvent Level, Formulation Variations, and Processing Technique Currently Characterizing AA-2 for ESTCP Nitrocellulose Based Propellant Manufacturing Waste Minimization Processing

Capillary Dies w/2" Press 2/40 3/40 4/40 5/40 6/40 5/25 9/12* 8/12* 7/12 6/12 5/12 *On Order x/y:x = die diameter (mm) y = length to diameter ratio To determine wall slip To determine end effects

Capillary Dies w/2" Press Solvent Based Materials Lova (EX-99) PAX-2A Shredder Propellant LI-10 (EX-98) Double Base AA-2 AA-6 TPE Based Materials GEM Gun Propellant GEM Rocket Propellant TPEMACS Gun Propellant –polyBAMO/AMMO –Hytrel® Extruded Composite Materials Characterized Include:

On-Line Adjustable Gap Die Used in Conjunction with 40 mm TSE Distance, (cm) Fixed gap width (W) Known volumetric flow rate (Q) Change gap height (H) Measure pressure, P(z) Determine apparent shear rate ( ) pressure gradient ( ) shear stress (  w ) shear sensitivity index (n) Change throughput, Q, to determine wall slip

Slit Die Used in Conjunction with 40 mm TSE Determine Rheological Behavior of Materials Processed on the TSE –Energetics containing solvents (e.g., Lova) must be tested on-line or batch processed and tested in a capillary die Solvent loss Are material properties the same (batch vs. continuous?) –Energetics based on TPEs can be processed on the TSE and then tested in a capillary die Are material properties the same (batch vs. continuous?) Do rheological properties change due to heating & cooling?

Slit Die Used in Conjunction with 40 mm TSE Characterized Lova and Airbag Simulant as a Function of Temperature and %Solvent with the On-Line Slit Die Pressure (P) vs Distance (z) Lova, 6.8 kg/hr, 13 wt% solvent, 49  C

Haake Torque Rheometer Old Machine – 2+ generations from latest model To date, mostly used as a small scale compounder (~ 60 cm 3 ) Variety of formulations –GEM Rocket Propellant –Lova –Thermobarics –ESEM IM Propellant –Nanoaluminum Formulation –Red Phosphorous Flares

Haake Torque Rheometer Monitor Torque vs. Time Binder Melt Solids Incorporation

Haake Torque Rheometer Procuring New Haake Torque Rheometer –November/December '02 Delivery Date –Includes New Design Features –Up-to-Date Data Acquisition System –Includes Optional Clear Front Plate for Flow Visualization

Lab Scale Capillary Rheometer 3/10 2/10 1/10 2/5 2/15 1/20 0.5/20 x/y:x = die diameter (mm) y = length to diameter ratio To determine wall slip To determine end effects Procured/Installed a Goettfert Lab Scale Triple Bore Capillary Rheometer Material Can Be Extruded through 3 Capillary Dies Simultaneously Requires ~100 grams for Preliminary Characterization – Use when only small amounts of material are available Dies:

Using to investigate the effect of nanoparticles on formulation viscosity Lab Scale Capillary Rheometer

Rheological IHDIV NSWC Continuing to Expand Rheological Capabilities –Procuring Additional Capillary Dies for the 2" Press to Determine the Wall Slip Behavior of Highly Viscous Material (e.g., double base) –Procuring a New Haake Torque Rheometer Higher Resolution of Torque Improved Safety Features –Improved the Design of the On-Line Slit Die –Obtaining Permission to Process Energetic Materials in the Lab Scale Capillary Rheometer