poster comptetion-phbv ns
TRANSCRIPT
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Toughening Bioplastic Materials with Nanosprings for Improved Strength Qualities
Bryce Dinger
Renewable Materials Program, University of Idaho, Moscow ID 83844-1132
• Issues with Conventional Plastic
Environmental pollution both terrestrial and marine
• How to Overcome These Issues
Substitute non-degradable petrochemical based polymers
with bioplastics (biodegradable and/or bioderived plastics)
• Bioplastics
Good biodegradability qualities
Generate fuel by anaerobic digestion
Divert waste from landfills
Can contribute to healthier rural economies
Can be made from a variety of renewable resources
Introduction
Bioplastics and Nanosprings
3-hydroxybutyrate-co-3-
hydroxyvalerate (PHBV)
Problems with PHBV
1. Formation of large
spherulites
2. Low nucleation densities
3. Low toughness (brittle)
Tensile Tests
Spherulite MorphologyImages taken from hot-stage polarized light optical microscopy
DSC Curves
Conclusions
• It was found that nanosprings resulted in
higher nucleation densities allowing more
sites for crystal spherulites.
• Through tensile tests it was found that the
PHBV + 1% NS composites required more
energy to break (tougher) than PHBV
controls, whilst having a decreased average
tensile stress and modulus of elasticity.
• The spherulites morphology of PHBV + 1% NS
composites showed smaller, densely packed
spherulites increasing its strength properties
making it less likely for cracks to propagate.
Acknowledgments
• University of Idaho OUR program for financial
support
• Dr. Armando McDonald (Renewable Materials
Program) as a faculty mentor
• Dr. David Mcilroy (Physics Department) for
supplying the nanosprings
• Ms. Shupin Luo (visiting scholar from Beijing
Forestry University) for her technical help
PHBV
Sample Preparation via Compound &
Injection Molding
RESIN MATRIXNanosprings
Propagating crack
Crack stopped propagating
Silica-
Nanosprings
Carbon Cycle of PHBV
Plant derived raw material
Bacteria
Fermentation
PHA polymer
(granules)
Biodegradation
Photosynthesis
RECYCLED
• Biocomposites preparation:
Compound using a Dynisco lab
mixing extruder/molder (LMM)
Nanosprings (NS): 0.01 wt%
Processing temperature: 175 C
Processing time: 7 min
Sample injection molded into dog-
bone specimens
PHBV PHBV + 1% NS
PHBV + 1% NS PHBV
• PHBV pictured here show
large fractured spherulites
averaging 0.56 mm in
width.
• PHBV + 1% NS showed high
nucleation densities and much
smaller spherulites with an
average width of 0.16 mm.
• PHBV showed slightly higher average maximum tensile stress than PHBV +
1% NS. PHBV also had a significantly larger Modulus of Elasticity than
PHBV + 1% NS.• The PHBV + 1% NS showed a
higher average energy at
break. This is consistent with
the microscopy because the
denser nucleation sites allowed
for better coupling and a less
brittle sample than the control
(PHBV).
• Differential scanning calorimetry (DCS) tests showed that
addition of 1% NS reduced PHBV crystallinity from 64% to
59%. This was consistent with the microscopy findings since
the NS created a greater amount of nucleation sites and
thus formed smaller spherulites with lower crystalynity.
PHBV Heat Flow Diagram PHBV NS Heat Flow Diagram
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PHBV NS
Carbon fibers
Carbon fibers
nanospringRESIN MATRIX
Interlayer
RESIN MATRIXNanosprings
Propagating crack
Crack stopped propagating
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