self-healing materials
TRANSCRIPT
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
• 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
• 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
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
SELF-HEALING COPOLYMERS
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
• Prepared samples
• Damaged samples
• Placed samples in scanning cell
• Scanned samples continuously over several hours
SELF-HEALING COPOLYMERS
• 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)
• 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)
• 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)
• 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)
EVOLUTION OF RESONANCE PEAKS DURING HEALING
Overlapping Resonance Peaks
Nucrel 960 8x8mm Sample
Damaged by Nail
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
QUALITY FACTORS OF RESONANCE PEAKSNucrel 960
8x8mm Sample Damaged by Nail
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
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
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
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
ACKNOWLEDGEMENTS• Rollins College Student-Faculty Collaborative
Scholarship Program • DuPont