Download - Self-Healing Materials
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INVESTIGATION OF SELF-HEALING COPOLYMERS UTILIZING TIME
DEPENDENT RESONANT SPECTROSCOPYNicholas R. Bowers, Physics Major
Kenneth A. Pestka II, Assistant Professor Joseph N. Kistner, Physics Major
Rollins College !
Stephen J. Kalista Jr. Union College
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• Idea. Explore self-healing behavior of copolymers by analyzing changes in their acoustic properties over time
• Goal. Determine healing timeframe for different copolymers to identify factors that may influence the healing process
PURPOSE OF INVESTIGATION
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• Triggered by sufficient energy transfer
• Three proposed phases of healing
• Instantaneous elastic molten state
• Welding and sealing
• Solid polymer interdiffusion and realignment
• Compositional variation, damage amount and mechanism, and sample age and deterioration may all influence the healing action of these polymers
[1] S. J. Kalista, T. C. Ward, “Thermal characteristics of the self-healing response in poly (ethylene-co-methacrylic acid) copolymers”, Journal of the Royal Society Interface. (2006).
Adapted from [1].
SELF-HEALING BEHAVIOR OF COPOLYMERS
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SELF-HEALING COPOLYMERS
• Poly (ethylene-co-methacrylic acid) copolymers (EMAA copolymers)
• Four different materials developed by DuPont which differ in molecular weight, ionic content, and material age
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SELF-HEALING COPOLYMERS
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SELF-HEALING COPOLYMERS
Nucrel (Non-ionic) Suryln (Ionic)
Greater Molecular Weight
Lesser Molecular Weight
60% of Acid Groups Neutralized by Na
30% of Acid Groups Neutralized by Na
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• Prepared samples
• Damaged samples
• Placed samples in scanning cell
• Scanned samples continuously over several hours
SELF-HEALING COPOLYMERS
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• Resonance spectrum depends on microscopic structure and sample geometry
• Microscopic structure evolves throughout the healing process
• Expect changes in the resonance spectrum during healing process
• Analyze trends in the time evolution of the spectrum to quantify healing mechanism
ACOUSTIC AND ULTRASONIC TIME DEPENDENT RESONANT
SPECTROSCOPY (TDRS)
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• Resonance spectrum depends on microscopic structure and sample geometry
• Microscopic structure evolves throughout the healing process
• Expect changes in the resonance spectrum during healing process
• Analyze trends in the time evolution of the spectrum to quantify healing mechanism
ACOUSTIC AND ULTRASONIC TIME DEPENDENT RESONANT
SPECTROSCOPY (TDRS)
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• Resonance spectrum depends on microscopic structure and sample geometry
• Microscopic structure evolves throughout the healing process
• Expect changes in the resonance spectrum during healing process
• Analyze trends in the time evolution of the spectrum to quantify healing mechanism
ACOUSTIC AND ULTRASONIC TIME DEPENDENT RESONANT
SPECTROSCOPY (TDRS)
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• Resonance spectrum depends on microscopic structure and sample geometry
• Microscopic structure evolves throughout the healing process
• Expect changes in the resonance spectrum during healing process
• Analyze trends in the time evolution of the spectrum to quantify healing mechanism
ACOUSTIC AND ULTRASONIC TIME DEPENDENT RESONANT
SPECTROSCOPY (TDRS)
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EVOLUTION OF RESONANCE PEAKS DURING HEALING
Overlapping Resonance Peaks
Nucrel 960 8x8mm Sample
Damaged by Nail
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0.000#
0.020#
0.040#
0.060#
0.080#
0.100#
0.120#
0.140#
0.160#
545# 550# 555# 560# 565# 570# 575# 580# 585# 590# 595#
Energy#(R
ela6
ve)#
Frequency#(kHz)#
#t=0h# #t=0.35h# #t=10.3h#
EVOLUTION OF RESONANCE PEAKS DURING HEALING
Nucrel 960 8x8mm Sample
Damaged by Nail
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QUALITY FACTORS OF RESONANCE PEAKSNucrel 960
8x8mm Sample Damaged by Nail
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0"
50"
100"
150"
200"
250"
300"
0" 1" 2" 3" 4" 5" 6" 7" 8" 9"
Quality"Factors"
Time"(Hours)"
"563kHz" "572kHz" "580kHz"
EVOLUTION OF QUALITY FACTORS DURING HEALING
Nucrel 960 8x8mm Sample
Damaged by Nail
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0"
50"
100"
150"
200"
250"
300"
0" 1" 2" 3" 4" 5" 6" 7" 8" 9"
Quality"Factors"
Time"(Hours)"
"563kHz" "572kHz" "580kHz"
EVOLUTION OF QUALITY FACTORS DURING HEALING
Nucrel 960 8x8mm Sample
Damaged by Nail
Phase 3
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0.0# 0.5# 1.0# 1.5# 2.0# 2.5# 3.0# 3.5# 4.0# 4.5# 5.0# 5.5# 6.0# 6.5# 7.0# 7.5# 8.0# 8.5# 9.0# 9.5# 10.0#
Phase#2#
Phase#3#
Time#(Hours)#
925# 960# 8920# 8940#
PRELIMINARY HEALING TIMEFRAMES
Greater Molecular WeightLesser Molecular Weight
Higher Ion ContentLower Ion Content
925
960
8920
8940
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PRELIMINARY RESULTS AND SUMMARY
• Preliminary results
• Establish healing timeframe estimates for four EMAA copolymers
• Confirm TDRS is a useful tool for determining healing timeframe
• Are consistent with the three-phase healing model
• Correlation between material composition and healing timeframe
• Correlations between healing timeframes and sample age, size, and damage amount are being explored
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ACKNOWLEDGEMENTS• Rollins College Student-Faculty Collaborative
Scholarship Program • DuPont