U.S. Army Research, Development and Engineering Command Transient Thermal Stability of Polymer Nanocomposites Dr. Stephen Bartolucci, Dr. Jeffrey Warrender, Dr. Karen Supan U.S. Army ARDEC Benet Laboratories DOD Multifunctional Materials for Defense 2012
Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE AUG 2012 2. REPORT TYPE 3. DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Transient Thermal Stability of Polymer Nanocomposites 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Research, Development and Engineering Command,Benet Laboratories,Watervliet Arsenal,NY 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR S ACRONYM(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited 11. SPONSOR/MONITOR S REPORT NUMBER(S) 13. SUPPLEMENTARY NOTES Presented at the 2nd Multifunctional Materials for Defense Workshop in conjunction with the 2012 Annual Grantees /Contractors Meeting for AFOSR Program on Mechanics of Multifunctional Materials & Microsystems Held 30 July - 3 August 2012 in Arlington, VA. Sponsored by AFRL, AFOSR, ARO, NRL, ONR, and ARL. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Same as Report (SAR) 18. NUMBER OF PAGES 23 19a. NAME OF RESPONSIBLE PERSON Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18
Motivation Composites Weapon Systems/Components Energy Transduction
Motivation Nanocomposite properties DoD applications Lightweight Inexpensive Processible Good mechanical properties Weapon systems Components Munitions High-frequency high-voltage switching Bridging this gap requires understanding the kinetics of degradation under transient thermal loading
Temperature increase ( o C) Surface temperature (K) Transient Heating 1600 1400 1200 1000 800 600 400 10 7 o C/min ThermoGravimetric Analysis cannon 20 o C/min 2000 1500 1000 500 0 120mm cannon 0 4 8 12 time (ms) 200 0 5E-6 500 1000 1500 time (s) Six orders of magnitude difference in heating rate
Goal of this project Use polypropylene as a model system to investigate degradation kinetics during transient heating
Materials Isotactic Polypropylene + 0-50 wt % nanoclay (modified Montmorillonite, Nanocor masterbatch) (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 nh2o Multiwalled Carbon Nanotubes (Nanocyl masterbatch) 1 wt % carbon black Twin screw extrusion (190C)
Slow Heating Regime Thermogravimetric Analysis Nanospecies improve thermal stability as expected
Laser pulse heating Fiber optic cable Bandpass Filter ~ 1064 nm laser beam Photodetector r t 1064 nm notch filter Collimating lens Sample I ( ) 1 he n n..t =InA--- 1 11 TlcJ. Oscilloscope
Laser pulse heating Photothermal processes Thermal decomposition Laser beam nongaseous products Shock wave gaseous products Ablation plume/plasma Tilted to reduce plume/laser interaction heat
Real-time monitoring of irradiation High Speed Videos Surface T cools Surface T plateau
Thermogravimetric Analysis dc dt A f ( C) e E RT Obtain activation energy
Ch 1 (mv) Temperature Measurements 1. Measure emitted photopower at varying λ 18 16 14 12 10 8 6 4 2 0 0.00 2.00 4.00 6.00 8.00 10.00 Pulse duration (ms) 1100 nm 1150 nm 1200 nm 1310 nm 1350 nm 1450 nm 1550 nm 1600 nm 1650 nm
ln(n*λ^4) Ch 1 (mv) Temperature Measurements 1. Measure emitted photopower at varying λ 18 16 14 12 10 8 6 4 2 0 0.00 2.00 4.00 6.00 8.00 10.00 Pulse duration (ms) 1100 nm 1150 nm 1200 nm 1310 nm 1350 nm 1450 nm 1550 nm 1600 nm 1650 nm 2. Fit to Planck s Law at each time step 64.5 64.0 63.5 63.0 62.5 62.0 61.5 61.0 60.5 60.0 59.5 y = -0.0008x + 70.631 R² = 0.949 8000 9000 10000 11000 12000 13000 14000 hc/kλ
ln(n*λ^4) Temperature (K) Ch 1 (mv) Temperature Measurements 1. Measure emitted photopower at varying λ 18 16 14 12 10 8 6 4 2 0 0.00 2.00 4.00 6.00 8.00 10.00 Pulse duration (ms) 1100 nm 1150 nm 1200 nm 1310 nm 1350 nm 1450 nm 1550 nm 1600 nm 1650 nm 2. Fit to Planck s Law at each time step 64.5 64.0 63.5 63.0 62.5 62.0 61.5 61.0 60.5 60.0 59.5 y = -0.0008x + 70.631 R² = 0.949 8000 9000 10000 11000 12000 13000 14000 hc/kλ 1400 1200 1000 800 600 400 200 3. Calculate temperature 0 0 2 4 6 8 10 time (ms)
Mass Change (µg) Mass change 700 Mass Change vs. Energy at 1.8 kw/cm^2 600 500 400 300 200 100 Polypropylene CB-MWNT-0.5% CB-MWNT-1% CB-MWNT-2% 0 2.0 2.2 2.4 2.6 2.8 3.0 3.2 Energy (J) Vary pulse duration Nano-Clay and Nanotubes decrease mass loss during LPH
Mass loss (mg) Real-time mass measurement Nd:YAG Laser Quartz Crystal with Polymer Film and Laser Spot Time (ms) Sample Quartz crystal Frequency Counter 4.952353 MHz Data recording And calibration program Quartz Crystal Microbalance
mass change (micrograms) Mass change vs. clay content 500 400 300 0 10 20 30 40 50 60 wt% clay The mass change after a 10 ms shot is reduced as clay content increases
counts Si2p Si2s O1s C1s Al2p Al2s FE-SEM 1000x PP-0% PP-5% PP-10% magnification PP-25% PP-50% shot PP-5% unshot 1200 1000 800 600 400 200 0 Energy (ev) Smooth surface: lower threshold fluence, higher ablation rate and increased gaseous decomposition products seen in polymer ablation *Lippert, 2003, Chem. Rev.
Chemical changes We are looking at chemical changes before and after LPH TGA-Mass Spectrometry (LPH-MS goal) Polymer ablated (loss of C-H bonds) Clay/Oxides remain on surface FTIR of clay nanocomposites
Multi-Pulse Behavior PP PP-25wt% nanoclay PP-2wt%MWNT X=(2Dt) 0.5 # α t Becomes a diffusion limited Problem. heat mass
Multi-Pulse Behavior Multi-Pulse Behavior 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 mm 0 50 100 150 PP 200 250 300 µm Maximum depth : 191 µm Area of the hole : 0.539 mm2 Maximum height : 7.48 µm Area outside : 59 µm2 µm 100 80 60 40 20 0-20 -40-60 -80 25% clay 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 mm Maximum depth : 53.9 µm Area of the hole : 48758 µm2 Maximum height : 35.5 µm Area outside : 9557 µm2
Summary Research the behavior of polymer nanocomposites during LPH Temperatures exceed melting point and degradation temp of base polymer Nanoclay and Nanotubes provide degradation resistance Novel TGA-LPH technique being developed
Acknowledgements US Army Benet Labs Dr. Karen Supan NRC Post-doc Student hires Christopher Davis (MIT), Sara Duenas-Wolfson (Cornell) University of Southern Mississippi Prof. Jeffery Wiggins Lawrence La Beaud Dr. Mohammad Hassan