Carbon Nanotubes to Improve
Mechanical Properties of Epoxy
Matrix Composites
Eliza Montgomery
The Pennsylvania State University
Physics and Applications of Nanoscale 1D Systems
Dr. Slava Rotkin – Lehigh University
CNT in Epoxy Matrix
• Replace current carbon fiber and carbon black
reinforcement materials
• Increase mechanical properties
• Enhance electrical and thermal properties*
• Proposed as a damage-sensing component*
*will not be addressed in this presentation
Objectives
• Compare tensile properties of different carbon
reinforcement materials for epoxy-based
composites: single, double, and multi-wall
nanotubes with and without functionalisation to
carbon black
• Address dispersion issues of carbon material in
epoxy related to tensile properties
Methods of Dispersion
in Epoxy Matrix
DWCNT with NH2 functionalisation:
Schematic of calendering process:
• Sonification-poses
problems due to extreme
vibration
• Calandering method
used to achieve
dispersion after stirring
Three-roll calander used for the effective dispersion of carbon
nanotubes in an epoxy matrix (a). The flow conditions in the roller
Dispersedare
into
epoxy via shown (b)
clearance
schematically
Dispersed
into
epoxy via
Carbon
black
dispersed
calandering
sonification
via
calandering.
FH Gojny, MHG Wichnamm, U Kopke, B Fiedler, K Schulte, Composites
Schwarz,
Ebeling,
Furth, Kunststoffverarbeitung.
Science
and Technology
64 (2004) 2363-2371 Vogel Buchverlag 2002.
Why Functionalize?
Dispersion and Surface
• Interfacial
adhesion
between CNT and matrix
Specific
Area (SSA)
of
polymer. CNTs
Functionalized
• Improves
stress
•High
SSA valuesinterfacial
positively relate
to transfer
stress
transfer dueof
to CNT
increased
dispersion
in matrix
interfaces between CNT and matrix
and
• Specifically: CNT is amino-functionalised to
2/gto
•High
SSA
values
negatively
relate
e)
SWNT
SSA
=
1300m
DWNT
c)
w/out and
and
w/ NH
Epoxy/MWCNT
b) w/d)and
a) 2
enable covalent bonding between
CNT
dispersion by
increasing
strong
2/g
w/out= NH
2
f)
Carbon
black
SSA =
SSA
600-800m
epoxy.
attractive forces
~1m2between
/g or less CNTs that
SSA = 200m2/g
lead
to excessive
• Relation
ofagglomeration.
amino-groups to the number of
surface carbon
atoms
•Functionalisation
decreases
the of the CNT is ~ 1/100.
SSA, leading to better dispersion.
FH Gojny, MHG Wichmann, B Fiedler, K Schulte, Composites Science and
Technology 65 (2005) 2300-2313
Mechanical Properties
• Strength
• Stiffness
• Fracture
toughness
•DWNT chosen:
best improving
mechanical
strength overall
FH Gojny, MHG Wichmann, B Fiedler, K Schulte, Composites Science and
Technology 65 (2005) 2300-2313
Highlights for DWCNT
in Epoxy Matrix
• Stress vs. strain = functionalized
performed best
• SEM micrographs of
fracture surfaces
a) w/out and b) w NH2
FH Gojny, MHG Wichmann, B Fiedler, K Schulte, Composites Science and
Technology 65 (2005) 2300-2313
Conclusions
• Dispersion difficult with larger SSA (all
CNTs).
• Functionalism improved dispersion of
CNTs in epoxy matrix for all cases.
• Addition of DWNT with 0.5% filler
increased mechanical properties best:
10% strength, 15% stiffness, and 43%
fracture toughness.
Thank you
Questions?
• Presentation primarily based on works by Gojny et al, 20032005