22
Content
• Who is IVW?
• Standard Applications for Natural Fiber
Composites
• Main Challenge – Mechanical Performance
• BioBuild Materials
• Manufacturing Methods
• Results
• Summary
33
Who is IVW?
Established: 1990
Budget: 35 % State, 65 % External
Internal Research Projects
New Ideas, Exploratory Work,
Fundamentals (DFG, RLP)
Governmental Research Projects
Funded Research Work
(BMBF, BMWI, EU,…)
Industrial Projects & Cooperation
New Developments in
Technology and Application,
Industry Funded Research,
Service Contracts
Cooperation-
contract with TU
Role in the BioBuild Project
Competence Field Materials Science:
Treatment of natural fibers yielding water- and
fire-resistant “green” coatings on the fibers’
surface by using bio-derived super-
hydrophobic phenalkamines and water glass
Competence Field Manufacturing Science:
Processing of biocomposite panels and
profiles in a continuous compression molding
process by using pre-impregnated textiles
developed in a previous WP
44
Standard Applications for
Natural Fiber Composites
• Since decades common use in the automotive industry for semi-
structural components
• Door panels
• Backrests
• Roof stiffenings
• New application fields
• Sports
• Furniture
• Ship building
• Usage of „Green Composites“
Mercedes E-Class Mercedes C-Class
Source: Global Hemp
Sourc
e: w
arw
ick.a
c.u
k
55
Fibers
Fiber web
Carding line Cross lapping
Mat compaction
Needling
NF-mats
• Fibers are almost randomly distributed in the non-woven
• 95 % of all natural fiber composites are manufactured by
compression molding, 5 % injection and others
• Fiber weight content in NFC not comparable to GFC
• 40 - 50 wt.-% for thermoplastic matrices
• 50 - 70 wt.-% for thermoset matrices
Standard Manufacturing Process
66
Main Challenge –
Mechanical Performance
Influence of fiber orientation in reinforcing textiles
Fiber weight fraction [%]
Stiffness
Strength
Uni-directional
natural fiber textile
Bi-directional
natural fiber textile
Multi-directional
natural fiber textile
77
Influence of density on E-Modulus
Main Challenge –
Mechanical Performance
0
1000
2000
3000
4000
5000
6000
0,75 0,8 0,85 0,9 0,95 1 1,05
Density [g/cm³]
E-M
odulu
s [
MP
a]
Low compression
low density
high porosity
High compression
high density
low porosity
Same natural fiber material
Standard
NF/PP material
for automotive
applications
88
BioBuild Materials
• Increasing the mechanical performance by using aligned fibers
• Use of furan resin as an agricultural waste product from the sugar
industry
• Use of leftovers from the cork stoppers manufacturing
cork composites
Fla
xJu
te
Bast fiber bundles Natural fiber textile
Co
rk
co
mp
osite
Co
rko
ak
99
Impregnation of Textiles
• Impregnation of textiles with furan resin
Production of prepregs
• Excess resin is squeezed out in the sqeeze rollers
• Subsequent press process in order to produce finished parts
Naturfaservlies
Matrix
FoulardImprägniertes
Vlies
Trockner Produktionsrichtung
Naturfaservlies
Matrix
FoulardImprägniertes
Vlies
Trockner Produktionsrichtung
NF textile
Furan resin
Foulard
Dryer
Prepreg
1010
Compression Molding
• Natural fibers are
pressure sensitive (max. 60 bar)
temperature sensitive (degradation at 200 °C)
• Natural fiber composites always contain porosity
decreasing density and mechan. performance
• Furan resin cures by a
polycondensation reaction
steam occurs
MatrixMatrix porosity
Lumen
Impregnation
porosity
Interface
porosityFiber
1111
Compression Molding
Optimization of compression molding process in order to increase
the density and reduce porosity content in the composite
repeated opening of the mold to
release the steam
Isochoric pressing with distance plates
for defining the end volume
higher density
of composites
1212
Continuous Compression Molding
• Production of almost endless panels, sandwiches, and profiles
using the CCMM
• Works on the basis of a semi-continuous process with alternating
press and transport stages
Unwinding stations
Press assembly
Material feed unit
Flax/furan
prepregCork roll Endless Profile
1313
Other Processing Methods
Vacuum infusion
• Resin mixing, cutting of
textiles, infusion, sectioning
and cutting
• Resin cures at RT (48 h)
Pultrusion
• Fiber reinforcement is
saturated with a resin and
pulled through a heated die
• Requirements for the resin are
high pot life, low viscosity, high
reactivity, and low amount of
volatiles
1414
Results - Natural Fiber Composites
• Tensile modulus of flax/jute-
furan composites much higher
than of standard NF materials
• Lower natural fiber weight
content
• Mechanical performance of NF
composites depends on density
Improving the mechanical performance of natural fiber
composites by using aligned fibers and optimizing the
manufacturing process (increasing the density)
Standard NF/PP Standard NF/DP Flax / furan Jute / furan0
2000
4000
6000
8000
10000
approx.
50 % NF36 % NF47 % NF
approx.
65 % NF
Tensile Properties
Yo
un
g's
Mo
du
lus [M
Pa
]
ρ = 0.8 – 0.85 g/cm³ ρ = 1.3 g/cm³
Flax/jute furan composite
1515
Results - Cork Sandwiches
• Combination of high performance NF composites with cork core
Improving the effective bending stiffness
Increase of Charpy impact resistance
• Correlation of performance to cork thickness
5 mm cork
(dried)5 mm cork
6 mm cork
10 mm cork
No cork0
1000
2000
3000
4000
Eff
ective
be
nd
ing
stiff
ne
ss [
kN
mm
²]
1 - 5 m
m
2 - 5m
m
3 - 5m
m
4 - 5 m
m
5 - 6 m
m
6 - 6 m
m
7 - 10 m
m
8 - 10 m
m
R - 0 m
m0
2
4
6
8
10
12
14
16
dried
no
cork
10 mm cork6 mm cork
Ch
arp
y I
mp
act
Re
sis
tan
ce
[kJ/m
²]
5 mm cork
dried
Flax furan cork composite
1616
Summary
• Standard applications of natural fibers in Europe in the automotive
industry for semi-structural components
• For the application as structural parts mechanical performance must
be increased
• Increase of mechanical properties due to aligned fibers (textiles) and
optimization of the manufacturing process (high density)
• Increase of bending behavior and Charpy impact resistance due to
the use of cork composite as sandwich core material
1717
Thank you for your attention
Acknowledgement
The research leading to these results has received funding from the
European Community’s Seventh Framework Programme
(FP7/2007 - 2013), under grant agreement Nº 285689.
Contact:
Dipl.-Ing. Jovana Džalto
Institut für Verbundwerkstoffe GmbH
67663 Kaiserslautern, Germany
Tel.: +49 (0)631 2017-437
E-Mail: [email protected]