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Structure-properties relations and application
of biofibre reinforced composites
Biobased Business Event, Emmen, March 17th 2015
Martien van den Oever, Harriëtte Bos
1 mm
Content
Structure-properties relations of biofibre reinforced composites
● Biofibres (flax as example)
● Natural fibre mat thermoplastics (NMTs)
● Injection moulding compounds
Applications
Recent developments
Wageningen UR - FBR …to explore the potential of nature to improve the quality of life…
Structure-properties relations in biofibres(Flax as example)
Structure of Flax bast fibre: Composite like
Structure of Flax Bast Fibre
Fibril angle: 10° for flax
● Angle ↑ strength ↓
Surface ‘contamination’
● Reduced fibre-matrix interaction, t
Lateral bonds depending on extraction process
Chemical composition of biofibres
Cell Hemi Lignin Pectin Ash Extractives
(%)
Flax 80 9 1.7 2.2 1.5 5
Hemp 82 7 2 3 2
Jute 60 11 15 4 2
Kenaf 55 14 10 4 2
Ramie 77 4 1 4 10
Cotton 91 1 0.4 2 3
Wood 44 21 29 2 2
Straw 38 20 19 1 8 15
…
Flax fibre strength
0
500
1000
1500
2000
0 20 40 60 80 100
Gauge length (mm)
Fib
re s
trength
(M
Pa)
Technical fibre
Elementary fibre; mechanical pre-isolation
Elementary fibre; lab. isolation
Bos, J Mater Sci 37, 2002, 1683-1692
Single plant cell
Fibre bundle
Biofibre-matrix adhesion
Flax-MAPP adhesion reaches theoretical maximum value
Van den Oever, Adv Comp Letters 7 (3), 1998, 81-85
Optimum biofibre-matrix adhesion often requires cleaning of fibre surface
Structure-properties relations in Natural fibre mat thermoplastic (NMT)
Tensile strength of flax-PP NMT
0
20
40
60
80
0 0.1 0.2 0.3 0.4 0.5
Fibre volume fraction [ - ]
Tensile
str
ength
[M
Pa]
GMT Kelly-Tyson model
Lateral fibre strength issue Lower strength due to lower fibre strength
25 mm
Scutched:Hackled:Open: PPSolid: MAPP
6 mm
Tensile modulus of flax-PP NMT
0
2
4
6
8
10
0 0.1 0.2 0.3 0.4 0.5
Fibre volume fraction [ - ]
E-m
odulu
s [
GP
a]
GMTCox-Krenchel model
Similar modulus at 20-30% lower density
Van den Oever, Applied Comp Materials 7, 2000, 387-402
Scutched:Hackled:Open: PPSolid: MAPP
Flexural modulus of flax-PP NMT
0
2
4
6
8
0 0.1 0.2 0.3 0.4 0.5
Fibre volume fraction [ - ]
Fle
xura
l m
odulu
s [
GP
a]
GMT
Lateral fibre strength issue
Scutched:Hackled:Open: PPSolid: MAPP
Charpy unnotched impact of flax-PP NMT
0
10
20
30
40
0 0.1 0.2 0.3 0.4 0.5
Fibre volume fraction [-]
Charp
y im
pact
[kJ
/m2]
GMT
Pull out energy lowerdue to: Fibre diameter larger,
relative fibre pull out surface lower
Fibre strength lower, pull out length lower
Van den Oever, Angew Makromol Chemie 272, 1999, 71-76
Scutched:Hackled: Open: PPSolid: MAPP
Structure-properties relations in Injection moulding compounds
Injection moulding compounds
Extrusion compounding
● Dispersion of biofibres in polymer
● Fibre refining and breaking
● Depends on fibre characteristics
Injection moulding
Granules
Extrusion compounding
Fibre +(bio)plastic
Product
Flexural strength Flax-PP compounds
Flax-MAPP
PP
Bos, Composites Part A 37, 2006, 1591-1604
Glass-MAPP
Lower fibre strength Shorter fibre length
Biofibre reinforced composites: Further Potential
Flax-PP Compounds
Flax-PP NMT
Bos, Composites Part A 37, 2006, 1591-1604
Compounds: Fibre length < lc Large improvement possible NMT: Fibre length > lc Potential used already
Single plant cells
Fibre bundles
IM compounds: Limit cycle time
Van den Oever, Applied Polym Sci 110, 2008, 1009-1018
0
20
40
60
80
100
120
0 5 10 15
Cycle time (min)
No
rma
lize
d p
rop
ert
ies (
%)
Strength
Stiffness
Impact
50 wt.% Jute-PP
IM compounds: Increased UV stability
0
20
40
60
80
100
120
0 10 20 30 40 50 60
UV Irradiation (days)
No
rma
lize
d p
rop
ert
ies (
%)
Strength
Stiffness
Impact
Strength PP
Stiffness PP
Charpy PP
50 wt.% Jute-PP
PP
Van den Oever, Applied Polym Sci 110, 2008, 1009-1018
Applications of biofibre reinforced composites
‘Wood’ Polymer Composites (WPCs)
260 kton (67% Decking) in EU in 2012
Nova Institut, WPC/NFC Market Study 2014-03
Natural fibre mat composite panels
90 kton in EU in 2012
Nova Institut, WPC/NFC Market Study 2014-03
Injection moulding compounds
15 kton in EU in 2012
Nova Institut, WPC/NFC Market Study 2014-03
Injection Moulding also works in India
One concern only: You justneed to know how they work
Design products
Courtesy of JEC Composites
Developments
Nano fibres
Cellulose fibres with diameter < 100 nm
Wide range of sources: paper pulp, waste streams
Nano fibres: Expected benefits
Strength
Modulus
High temperature performance
Transparent materials
Barrier properties/slow release
Specific surface area
Suspension stabilisation
Resistance to moisture
Nano fibres: Refining from biofibres
Fibre refining
Flax
Paper pulp
Fibre dimensions 30-150 nm
Nano fibres: Extraction from waste streams
100 mm
1 mm
Streams rich in cellulose
Cellulose fibre extraction
Extraction yield needs to be increased
Nano fibres reinforced composites
Nano cellulose highly hydrophilic
Processable in water dispersable polymer
Translucent materials
Good strength and stiffness
Obstacles for wider use
● Fibres tend to agglomerate after being formed
● Fibres form H-bonds when being dried
● Processing in melt processable polymers requires further development
Durable soft wood
Modification of soft wood by resins from biomass
NATURAL RESINS
processed from plant waste
• Sugar canes
• Corn cobs
• Wood
HIGH QUALITY WOOD
1. Increased lifetime
2. Increased mechanical
properties
3. Consistent quality &
supply
4. Environmentally friendly
LOW VALUE WOOD
• Easily biodegradable
• Mostly soft (European Species)
• Moisture sensitive
• Inconsistent quality
ImpregnationCuring & Drying
Alternative fibre sources
Coconut husk
Opening Milling
Coconut
Binderless board from coconut husk
● No additional glue
Technology similar for other sources
Hardboard, Very strong
Pressing
Literature
Biocomposieten 2012, http://www.dpivaluecentre.nl/inspiratie/projects/boekje-biocomposieten/
Catalogus biobased bouwmaterialen, http://www.groenegrondstoffen.nl/downloads/Boekjes/15Catalogusbiobasedbouwmaterialen.pdf
Kennisbank biobased bouwmaterialen, www.biobasedbouwen.nl
Binderless boards from coconut husk, www.ecocoboard.net
Thank you for
your attention
Questions:
www.fbr.wur.nl
Biofibre-polymer composite processing
Fibre refining
Fibre pretreatment
Chemical modification
Extrusion compounding
Batch compounding
Injection moulding
Compression moulding
Biofibre-polymer composite analysis
Melt Flow Index (MFI)
Capillary / Disc viscosimetry
Tensile / Flexural testing (Climate chamber)
Charpy / Izod / Falling dart impact testing
Heat Deflection Temperature (HDT)
DSC
DTMA
SEM / TEM
(Solid state) NMR
UV irradiation
Chemical Composition
