Joshua Mangler1, P.R.Hondred2, M.S. Kessler2 1 Dallas Center-Grimes High School Grimes, Iowa

2Dept. Of Materials Science and Engineering, Iowa State University

Bio-polymers: characterization for self-healing

application.

MOTIVATION

OBJECTIVE

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

Ideal glass transition temperature

Thermal stability

MATERIALS AND METHODS

BACKGROUND

POLYMERIZATION PROCESS

THERMOGRAVIMETRIC ANALYSIS

DIFFERENTIAL SCANNING CALORIMETRY

CONCLUSION AND FUTURE WORK

Petroleum vs Biorenewables

Cost

Sustainability

Environment

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.

Macrocrack Microcrack

Time

Figure 1. Polymer crack progression over time

I sure wish I’d

presented my

theory with a

poster before I

wrote my book.

Healing Agent Catalyst

Crack forms

in material Crack ruptures

microcapsules

Healing agent

polymerizes

Figure 2. Self-healing concept showing microcapsules and catalyst

Figure 3. Scanning electron microscope images of ruptured microcapsules

+ +

Catalyst

Rare Earth

Triflates

Styrene

Divinylbenzene

Crosslinked Thermoset

Figure 7. Polymerization process

Figure 4. Chosen oil – tung oil

Figure 5. Chosen rare earth

triflates

Samarium

Triflate

Scandium

Triflate

Ytterbium

Triflate

Cerium

Triflate

Procedure: 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.

Chemical Ratio of Samples

Monomer

s

47% Tung oil

32% Styrene

16% Divinylbenzene

Initiator 5% Rare earth triflate

Table 1. Composition of monomers and initiator

Viscoelastic Behaviors of Polymers • Complex mechanical modulus

• Glass transition temperature

Testing Conditions Equilibrate at -50°C

Ramp 3°C/min to 150 °C

Figure 11: Storage

modulus of different

tung oil triflate

polymers

Figure 13: Tan

delta of different

tung oil triflate

polymers

Figure 12: Loss

modulus of different

tung oil triflate

polymers

Cerium Scandium Ytterbium Samarium

14.7°C 55.4°C 56.4°C 13.8°C

Testing Conditions Equilibrate at -50°C

Ramp 3°C/min to 200 °C

Glass Transitions of Polymer Cure • Heat flow compared to standard reference

• Glass transition temperature

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.

Reactivity

Figure 10: DSC cure of bio-polymers

Testing Conditions Ramp 20°C/min to 650 °C

Conclusion: •Effective cure temperature

•Good thermal stability

•Variable glass transition

temperatures

•Phase separation in cerium

triflate catalyzed bio-polymer

Future work: •Characterization of thermal

degradation

•Evaluate adhesive properties

•Evaluate crosslink density

•Characterization of phase

separation

DYNAMIC MECHANICAL ANALYSIS

DYNAMIC MECHANICAL ANALYSIS CONT’D

Table 2: Glass transition temperatures

Figure 8: (Above) Thermal

degradation of bio-polymer in air

Figure 9: (Left) Thermal

degradation of bio-polymer in

nitrogen

VARIABLE

STORAGE

MODULUS

VARIABLE GLASS

TRANSITION

TEMPERATURES

PHASE

SEPARATION IN

CERIUM

CATALYZED

BIO-POLYMER

Thermal Degradation • Monitors weight change as a function of

temperature or time

• Predicts thermal stability

• Monitors decomposition, oxidation, and

dehydration

CBiRC: NSF award EEC-0813570 (PI Shanks)

Figure 6. Tung oil bio-polymer samples catalyzed by rare earth

triflates. Rare earth triflate catalyst (from left to right), cerium,

scandium, samarium, ytterbium.