CELLULOSE NANOCRYSTALS FOR LIGHTWEIGHT SHEET MOLDING COMPOUNDS COMPOSITES Amir Asadi, Ferdinand Baaij, Robert Moon and Kyriaki Kalaitzidou G.W. Woodruff School of Mechanical Engineering and School of Materials Science and Engineering Georgia Institute of Technology
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CELLULOSE NANOCRYSTALS FOR LIGHTWEIGHT SHEET MOLDING COMPOUNDS COMPOSITES
Amir Asadi, Ferdinand Baaij, Robert Moon and
Kyriaki Kalaitzidou
G.W. Woodruff School of Mechanical Engineering and
SPECIFIC MECHANICAL PROPERTIES(DIVIDED BY DENSITY)
17
25GF/epoxy 25BF/epoxy
Tensile properties Flexural properties
FRACTURE SURFACE MORPHOLOGY
18
25BF/epoxy 25GF/epoxy
100μm
100μm 100μm
100μm
IMPACT STRENGTH
19
CONCLUSIONS
20
BF-reinforced SMC composites do not show advantages in terms of lightweighting.
However, they are a potential cost-efficient and ecofriendly alternative to GF/epoxy composites.
0
30
60
90
120
SpecificStrength
(MPa/g/cm^3)
0
2
4
6
8
SpecificModulus
(GPa/g/cm^3)
WHAT IS CELLULOSE?
21
Moon et al. Chem. Soc. Rev. 2011; 40, 3941-3994.
CELLULOSE NANO-CRYSTALS
22
Length (nm) 138±22 *
Width (nm) 6.4±0.6 *
Density (g/cm3) 1.6 **
Tensile strength (GPa) 7.5 – 7.7 **
Elastic modulus in axial direction (GPa)
110 – 220 **
Elastic modulus in transverse direction (GPa)
10 – 50 **
* Girouard et al., Polymer 2015; 68: 111-121.** Moon et al. Chem. Soc. Rev. 2011; 40: 3941-3994.
LIGHT-WEIGHTING OF SMC COMPOSITES BY ADDING CELLULOSE NANO-CRYSTALS (CNC)
23
Introducing CNC to the matrix
Coating the fibers with CNC Increasing the
Interfacial Shear Strength between fiber surface and
matrix
Increasing the mechanical
properties of the matrix
Ability to reduce fiber content
( and weight) without
compromises in the properties
Or
Increased properties of the composite with no compromises
in the density
Light-weight SMC parts:
Lower density
Or
Smaller thickness
Using the CNC-epoxy matrix, how much fibers can be reduced without compromising the specific properties compared to a composite with neat epoxy?
Micromechanical Model:
𝑬𝑪𝒐𝒎𝒑𝒐𝒔𝒊𝒕𝒆 =𝟑
𝟖𝑬𝟏𝟏 +
𝟓
𝟖𝑬𝟐𝟐
𝐸11 = 𝐸𝑚
1+2𝑙𝑓𝑑𝑓𝜂𝐿𝑣𝑓
(1−𝜂𝐿𝑣𝑓); 𝐸22 = 𝐸𝑚
1+2𝜂𝐿𝑣𝑓
(1−𝜂𝐿𝑣𝑓)
Predict fiber contents for CNC-epoxy composites with same specific modulus ascomposites with neat epoxy and a fiber content of 60% (maximum fiber content)
INTRODUCING CNC TO THE EPOXY MATRIX
24
ρ (g/cm3) E (GPa)
Neat epoxy 1.15 3.0±0.3
1.4CNC-epoxy 1.15 4.4±0.5
2CNC-epoxy 1.15 4.7±0.3
𝜂𝐿 =
𝐸𝑓𝐸𝑚
− 1
𝐸𝑓𝐸𝑚
+ 2𝑙𝑓𝑑𝑓
𝜂𝑇 =
𝐸𝑓𝐸𝑚
− 1
𝐸𝑓𝐸𝑚
+ 2
0
30
60
90
120
150
180
Sp
ecif
ic Im
pa
ct
En
erg
y,
kJ
/m2(g
/cm
3)-1 (c) GF/epoxy
BF/epoxy
Fiber content (wt %)
50 60 65 70
0
4
8
12
16
0
50
100
150
0.0
0.5
1.0
1.5
0
1
2
Speicific tensile properties (g/cm3)-1
GF/epoxy BF/epoxy
W
ork
of
fra
ctu
re
(M
J/m
3)
Mo
du
lus (
GP
a)
Str
en
gth
(M
Pa)
Str
ain
at
Bre
ak
(%
)
(a)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
0
10
20
30
0
100
200
300
0
1
2
0
1
2
3
Tensile properties
GF/epoxy BF/epoxy
W
ork
of
fractu
re
(M
J/m
3)
Mo
du
lus
(G
Pa
)S
tre
ng
th (
MP
a)
Str
ain
at
Bre
ak
(%
)
(a)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
DETERMINATION OF MAXIMUM FIBER CONTENT
25
0
10
20
30
0
100
200
300
0
1
2
0
1
2
3
Tensile properties
GF/epoxy BF/epoxy
W
ork
of
fra
ctu
re
(M
J/m
3)
Mo
du
lus (
GP
a)
Str
en
gth
(M
Pa)
Str
ain
at
Bre
ak
(%
)
(a)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
0
10
20
30
0
100
200
300
0
1
2
0
1
2
3
Tensile properties
GF/epoxy BF/epoxy
W
ork
of
fractu
re
(M
J/m
3)
Mo
du
lus
(G
Pa
)S
tre
ng
th (
MP
a)
Str
ain
at
Bre
ak
(%
)
(a)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
0
5
10
15
20
25
0
100
200
300
400
0
1
2
3
0
2
4
6
Flexural properties
GF/epoxy BF/epoxy
W
ork
of
fractu
re
(M
J/m
3)
Mo
du
lus (
GP
a)
Str
en
gth
(M
Pa)
Str
ain
at
Bre
ak
(%
)
(b)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
0
10
20
30
0
100
200
300
0
1
2
0
1
2
3
Tensile properties
GF/epoxy BF/epoxy
W
ork
of
fractu
re
(M
J/m
3)
Mo
du
lus
(G
Pa
)S
tre
ng
th (
MP
a)
Str
ain
at
Bre
ak
(%
)
(a)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
0
50
100
150
200
250
300(c) GF/epoxy
BF/epoxy
Fiber content (wt %)
Imp
act
En
erg
y (10
3J
/m2)
50 60 65 70
0
5
10
15
0
50
100
150
200
0
1
2
0
1
2
3
4
Speicific flexural properties (g/cm3)-1
GF/epoxy BF/epoxy
W
ork
of
fractu
re
(M
J/m
3)
Mo
du
lus (
GP
a)
Str
en
gth
(M
Pa)
Str
ain
at
Bre
ak
(%
)
(b)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
0
10
20
30
0
100
200
300
0
1
2
0
1
2
3
Tensile properties
GF/epoxy BF/epoxy
W
ork
of
fractu
re
(M
J/m
3)
Mo
du
lus
(G
Pa
)S
tre
ng
th (
MP
a)
Str
ain
at
Bre
ak
(%
)
(a)
Fiber content (wt %)
CNC content (wt %)
50 60 65 70
Almost no performance improvement above 60 wt% fiber content
Found 60 wt% as maximum fiber content with a good fiber wetting
LIGHT-WEIGHT COMPOSITES WITH CNC
26
Etheor (GPa) ρ (g/cm3) Especific,theor
60GF/epoxy 14.38 1.71 8.40
48GF/0.9CNC-epoxy* 13.23 1.56 8.48
44GF/1.1CNC-epoxy** 12.73 1.51 8.41
60BF/epoxy 14.99 1.76 8.48
48BF/0.9CNC-epoxy* 13.41 1.58 8.47
44BF/1.1CNC-epoxy* 13.17 1.54 8.52
* 1.4 wt% CNC in the epoxy** 2 wt% CNC in the epoxy
DENSITY AND VOID CONTENTS OF THE LIGHT-WEIGHT SMC COMPOSITES