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Influence of filler properties on the mechanical failure of a polymer nanocomposite A. Kutvonen , G. Rossi , T. Ala-Nissilä Multiscale Statistical Physics Group at COMP/Aalto. Polymer nanocomposites have a wide range of applications varying from car tyres to advanced coating technologies - PowerPoint PPT Presentation
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Influence of filler properties on the mechanical failure of a polymer nanocomposite
A. Kutvonen , G. Rossi , T. Ala-NissiläMultiscale Statistical Physics Group at COMP/Aalto
Polymer nanocomposites have a wide range of applications varying from car tyres to advanced coating technologies
How do parameters such as loading, filler material and topology influence the nanocomposite mechanical properties?
Nanocomposite behaviour during tensile deformation?
Molecular dynamics simulations
V(r) -> F(r) -> move ->V(r)
Bead-spring model for polymers+ Lennard Jones (LJ) – potentials
Periodic boundary conditions
Fillers with different topologies, masses and sizes
MODEL & METHODS
ε bf=4εnb ε ff=ε nb5
εnbkBT
=0.7
how much system resist strain
System equilibrated in NVT ensemble above glass transition temperature
Walls are moved with constant velocity
METHODS & STRESS – STRAIN CURVES
Strain
Str
ess
Elastic response Yield point Cavitation Big cavity
Stress-Strain curve-Indicates how system resists strain
RESULTS 1/3WHERE DOES THE
STRENGTH COME FROM?
All neighbours
Bead-bead neighbours
Filler-filler neighbours
Strain
Str
ess
9
Bead-filler neighbours
All neighbours
Num
ber
Fra
ctio
nF
ract
ion
Fra
ctio
n Before yield point the density of system is decreasing
Number of contacts reduces
Fraction bead-filler neighbours is increasing
RESULTS 2/3
Fixed volume loading Size comparison
Smaller fillers increase yield stress for cavitation
Is it because smaller fillers in total have a larger surface area?
No, even with constant surface area the smallest win
Smaller ones have better mobility
RESULTS 3/3 & WORK IN PROGRESS
Same number of fillers and same mass
vs.
Triangles might have more rigid behaviour
Study of the effects of: Mass of the filler Loading Stick and sheet shaped fillers Branching
IN PROGRESS:
Thank you for your attention!
MD SIMULATION PROTOCOL
Decompress and find equilibrium volume in microcanonical ensemble
Randomize initial positions and compress
Equilibration by annealing
Pull walls with constant velocity and gather data