Joshua Mangler , P.R.Hondred , M.S. Kessler

Bio-polymers: characterization for self-healing
application.
Joshua
1
Mangler ,
2
P.R.Hondred ,
M.S.
2
Kessler
1
Dallas Center-Grimes High School Grimes, Iowa
2Dept. Of Materials Science and Engineering, Iowa State University
CBiRC: NSF award EEC-0813570 (PI Shanks)
MOTIVATION
MATERIALS AND METHODS
THERMOGRAVIMETRIC ANALYSIS
DYNAMIC MECHANICAL ANALYSIS CONT’D
Thermal Degradation
Petroleum vs Biorenewables
• Monitors weight change as a function of
temperature or time
• Predicts thermal stability
• Monitors decomposition, oxidation, and
dehydration
Cost
Reactivity
Figure 11: Storage
modulus of different
tung oil triflate
polymers
Sustainability
Environment
Figure 4. Chosen oil – tung oil
Energy
Polymers made from biorenewables are gaining traction as an effective
and plausible alternative to petroleum based products. Continued
research into their properties and applications may yield sustainable
and cost effective alternatives and subsequently reduce society’s
dependency on oil.
Samarium
Triflate
Scandium
Triflate
OBJECTIVE
Ytterbium
Triflate
Our objective is to develop bio-based self healing polymers. The
research focuses on the healing agent and how different triflate
catalysts affect the thermal-mechanical properties of tung-oil based
thermosetting bio-polymers.
The thermal-mechanical properties
investigated were:
Effective cure rate and temperature
Cerium
Triflate
Figure 5. Chosen rare earth
triflates
Chemical Ratio of Samples
Monomer 47% Tung oil
s
32% Styrene
16% Divinylbenzene
Initiator
5% Rare earth triflate
VARIABLE
STORAGE
MODULUS
Testing Conditions
Ramp 20°C/min to 650 °C
Figure 12: Loss
modulus of different
tung oil triflate
polymers
Table 1. Composition of monomers and initiator
Procedure:
Figure 8: (Above) Thermal
degradation of bio-polymer in air
1) Rare earth triflate added to the
monomers and mixed for one minute
with horn sonicator.
2) Sample was placed into hot water
bath sonicator until cured. Times
varied per triflate.
3) Post cured at 150°C for five hours.
VARIABLE GLASS
TRANSITION
TEMPERATURES
Figure 9: (Left) Thermal
degradation of bio-polymer in
nitrogen
Ideal glass transition temperature
Figure 13: Tan
delta of different
tung oil triflate
polymers
Thermal stability
BACKGROUND
DIFFERENTIAL SCANNING CALORIMETRY
Time
Microcrack
• Heat flow compared to standard reference
• Glass transition temperature
PHASE
SEPARATION IN
CERIUM
CATALYZED
BIO-POLYMER
Macrocrack
POLYMERIZATION PROCESS
Figure 1. Polymer crack progression over time
Healing Agent
Glass Transitions of Polymer Cure
Figure 6. Tung oil bio-polymer samples catalyzed by rare earth
triflates. Rare earth triflate catalyst (from left to right), cerium,
scandium, samarium, ytterbium.
Catalyst
Testing Conditions
I sure wish I’d
presented my
theory with a
poster before I
wrote my book.
+
+
CONCLUSION AND FUTURE WORK
Equilibrate at -50°C
Ramp 3°C/min to 200 °C
Styrene
Divinylbenzene
Crack forms
in material
Crack ruptures
microcapsules
Healing agent
polymerizes
Catalyst
Rare Earth
Triflates
Cerium
Scandium
Ytterbium
Samarium
14.7°C
55.4°C
56.4°C
13.8°C
Figure 10: DSC cure of bio-polymers
Table 2: Glass transition temperatures
Future work:
•Effective cure temperature
•Good thermal stability
•Variable glass transition
temperatures
•Phase separation in cerium
triflate catalyzed bio-polymer
•Characterization of thermal
degradation
•Evaluate adhesive properties
•Evaluate crosslink density
•Characterization of phase
separation
DYNAMIC MECHANICAL ANALYSIS
Figure 2. Self-healing concept showing microcapsules and catalyst
Viscoelastic Behaviors of Polymers
• Complex mechanical modulus
• Glass transition temperature
Testing Conditions
Crosslinked Thermoset
Figure 3. Scanning electron microscope images of ruptured microcapsules
Conclusion:
Figure 7. Polymerization process
Equilibrate at -50°C
Ramp 3°C/min to 150 °C
ACKNOWLEDGEMENTS
Thank you to NSF for funding the summer RET program, Dr. Michael Kessler
for providing the opportunity to work within his polymer composite research
group, the members of the group – especially Danny Vennerberg - for their
support and assistance. A special thanks to Peter Hondred for his mentoring,
direction, and guidance.