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Introduction to Biocomposite Materials
Kristiina Oksman
Division of Materials Science
Composite Center Sweden
Luleå University of Technology
Content
• FiDiPro project at Oulu
• Information about LTU, CCSWE & Composites Master program at Luleå,
• Basics on composite materials
− Definitions
− Mechanical properties
− Role of reinforcement and matrix
• Biocomposites
− Why natural materials
− Fiber properties
− Used polymers
− Market trends
− Nanocomposites
FACULTY OF TECHNOLOGY
• FiDiPro professor Kristiina Oksman, Luleå University of Technology and
Composite Center Sweden
• 2 post-doctoral researchers + 2.5 doctoral students
• FiDiPro Research Project 2015 -2019
Development of biocomposites with better performance
Customer-oriented novel technologies for processing biocomposites
Strengthening the research excellence and academy-industry network for
biocomposites in Finland
Improving resource efficiency by using local waste and side-streams of the
wood and cellulose-based industries.
NOVEL HIGH-PERFORMANCE WOOD
AND CELLULOSE BIOCOMPOSITES
FACULTY OF TECHNOLOGY
• Project tasks / Post-Docs and PhD students
− Cross-linked, interpenetrated networks of biocomposites
− Biocomposite processing with fiber treatment
− Fast impregnation process for cellulose nanofiber networks
− Short projects in co-operation with the industrial partners
NOVEL HIGH-PERFORMANCE WOOD
AND CELLULOSE BIOCOMPOSITES
FACULTY OF TECHNOLOGY
• Close collaboration with Luleå University of Technology
• Around 20 Finnish companies involved in the project
• Value chain covered from material manufacturing to composite end-
users and recycling
NOVEL HIGH-PERFORMANCE WOOD AND
CELLULOSE BIOCOMPOSITES
www.ltu.se
19 000 students
1700 employees
www.ccswe.se
Master degree on composites 120 ETC Obligatory courses
Composite Materials
Biocomposites
Composite Design and
Numerical Methods
Organic and Biochemistry
Project course, 30 ECTS
Master thesis, 30 ECTS
Selectable courses
Advanced Materials Characterization
Techniques
Aerospace Materials
Materials Modelling
Materials Selection and Eco Design
Nanostructured Materials and
Nanotechnology
High Temperature Materials
Polymer Science and Engineering II-
Processing and Design
Mechanics of Fibre Composites
Composite
materials
Biocomposites Materials modelling Aerospace materials
Organic chemistry
and biochemistry
Composite
design and…
Polymer science and
engineering II…
Nanostructured
materials….
Year 1 (Example)
Project course 30 ETC Master thesis 30 ETC
Year 2
Some possible partners:
Materials made of two or more materials with
different physical or chemical properties and
when combined will results in a material with characteristics
which are different from the individual components
They consists of a matrix (resin) and reinforcement (fibers)
of different origins
The resin in polymer composites is thermoset or
thermoplastic and reinforcement is usually glass, carbon,
aramid or natural fibers
The properties and performances which offer composite
materials a huge field of applications are: light weight,
good mechanical properties, anti-corrosive, acoustic and
thermal insulation, easy upkeep and maintenance
What are composite materials?
Composite material
Fibers can be continuos or discontinuous
Matrix can be polymer (metallic and ceramic)
Continuous fibers High performance composites
+
=
Fibres Polymer resin Composite
+
=
Overall properties are determined by:
1. The properties of the fibers
2. The properties of the resin
3. The amount of fibers (fiber
volume fraction)
4. Geometry and orientation of
the fibers in the composite
Reinforcements: Types
Continuous
• Unidirectional
• Woven fabric
Discontinuous
• Chopped fibers
• Random mat
0o
0o / 90o
Effect of the fiber and matrix on mechanical
properties
Unidirectional
Tension (0°)
Compression (0°)
Shear
Tension (90°)
Fiber Matrix
X
X X
X
X
Main functions of the fibers and the matrix
Fibers
−To carry the load, in the structural composites 70-90% of
the load is carried by the fibers
−To provide stiffness, strength and thermal stability
−Can also provide electrical conductivity or insulation
Fibre properties
Fiber E-modulus
(GPa)
Strength
(MPa)
Strain
(%)
Length
(mm)
Diam.
(m)
Density
(g/cm3)
Glass 72 2000-3400 1.8-3.2 Cont. 10 2.56
Ramie 128 500-1000 1.2-4 60-250 10-80 1.4-1.5
Flax 45-100 600-1100 1.5-2.4 13-70 10-30 1.37
Sisal 19-32 490-760 2.2-2.9 1-8 10-40 1.45
Hemp 25-35 400-700 1.1-2 5-55 10-50 1.4-1.5
Jute 13-55 400-550 1.5-1.8 2-5 10-30 1.5
Kenaf 60 1100 - 2-6 10-20 1.5
Wood 30-40 400-800 - 3-5 20-40 1.54
Main functions of the fibers and the matrix
Matrix
−Bind the fibers together
−Transfers the load to the fibers
−Provide rigidity and shape for the product
−Separate the fibers, individual fibers can act separately
(stopping or slowing the crack propagation
−Surface finish quality
−Protect the reinforcing fibers against chemical attack or
mechanical damage
−Failure mode is strongly affected of the type matrix and
compatibility
−Provide ductility and impact properties
Most common thermoset resins in composites
Resins Advantages Disadvantages
Phenol/
Melamine/
Urea/
formaldehydes
•High environmental resistance
•Higher mechanical properties
than UPE
•Good adhesion with wood
•Low cost
•Phenolis are dark
•Formaldehyde emissions
•Brittle
•Water uptake
Polyesters (UPE) •Easy to use
•Low cost 20-40 SEK/kg
•Only moderate mech.
prop.
•High styrene emissions
•High cure shrinkage
•Limited working time
Epoxy •High mechanical and thermal
properties
•High water resistance
•Price 50-250 SEK/kg
Most common thermoplastic resins
Resin Advantages Disadvantages
Polypropylene
(PP)
•Easy to use
•Low cost 1.1 Euro/kg
•Environmental friendly
•Can be recycled and reformed
•Low processing cost
•High water resistance
•Only moderate mech.
prop.
•Low Creep
•Sensitive for low
temperature
•No adhesion
Polyethylene (PE) •Low cost 1 Euro/kg
•Good impact properties
•Good low temp properties
•Can be recycled
•High water resistance
•No adhesion
Poly vinyl chroride
(PVC)
•Good adhesion with wood •Not enviromental friendly
Trends: natural materials in composites
• Man made fibres are replaced with natural fibres
(car industry)
• Thermoset binders are replaced with more
environmentally friendly materials such as
thermoplastics (in WPC)
• Polymers which are biobased are also increasing
• Fibre reinforcements are decreasing in size
(nanomaterials)
Traditional wood compositesParticle board
• Wood particles
• Coarse particles in the middle and
fine particles at the surface
• Adhesive content 5-15%
• Furnitures, doors, building
− Low moisture stability
− High weight
• Used in furnitures, building
products (sheets)
Medium Density Fiber Board (MDF)
• Wood fibres
• Adhesive content
about 20%
• Interiour applications
Oriented Strand Board (OSB)
• Structural engineering
panel/board
• Long wood strands/chips
• Each layer is aligned
• Unique properties which
allows it to be used in many
different applications (roof,
floor etc)
• Adhesive: phenolic resin
approx. 10%
Wood thermoplastic composites
K. Oksman and M. Sain, Wood Polymer Composites, Woodhead Publishing Limited, 2008.
• Enviromental friendly materials
• Restproducts / wood and plastics
• Can be formed as plastics
• Wood content 50-80 wt%
• Better moisture stability than wood
• Research
−Develope next generation wood
composites
−New processing technologies
−Improve mechanical and long
term properties
• Building products, furnitures, etc
WPC Products
Biocomposites/Natural fiber composites
• Agrofibers /Plant fibers as reinforcements
− Flax
− Sisal
− Jute
− Hemp
− Kenaf
• Thermosets resins
− Polyesters, epoxy
• Thermoplastic resins
− Polypropylene
• Biopolymers
Why natural fibers in
thermoplastics?
• Improve mechanical properties
• Reduce price
• Ecological reasons
• Reduce weight
• Improve heat distortion resistance
• Reduce shrinkage
• Decrease the cycle time
• Change appearance
• Produce biodegradability
UPM Biofore
IKEA
Source: nova-Institut 2010 & 2011, AMI 2011, AVK 2010, Ellis, P. 2010
Bio-Composites in the EU 2010 (in tonnes)Estimated
Quantities in the
EU 2010
Forecast EU 2020
(under favourable
political framework)
Compression moulding 190,000 370,000
Natural fibres (flax, hemp, kenaf, jute, sisal, abaca, coir): (>95%
automotive)
40,000 120,000
Cotton fibres: automotive, mainly lorries 100,000 100,000
Wood fibres (WPC): mainly automotive 50,000 150,000
Extrusion and injection moulding 172,000 550,000
- Wood Plastic Composites (WPC): construction, furniture,
automotive, consumer goods
167,000
(incl. Norway &
Switzerland)
450,000
(incl. Norway &
Switzerland)
- Natural Fibres Reinforced Plastics: construction, furniture,
automotive, consumer goods)
5,000 100,000
Bio-Composites in total 362,000
(= 14%)
920,000
(= 29%)
Composites in total (glass, carbon, natural fibres &
wood)2.5 Million 3.2 Million
Source: nova-Institut 2010 & 2011
WPC production in the world 2010 (million tonnes)
World 2.5-3.0
Europe 0.22
North America 1.5
China 0.55
Materials
• PP, PE, PS, PVC, PLA
• WP, WF, CF, NF
Compounding (Extrusion)
• Direct extrusion of profiles
• Pellet (granulate)
− Injection molding
− Profile extrusion
• Sheet (or sausage)
− Compression molding
Compression molding / Thermoforming
• Nonwoven mat of fibers
Thermoplastic biocomposites
Compounding (melt mixing) extrusion
High temperature
Feeding
Shear
Co-rotationg twin screw extruder
Basic Lay-out and Main Components
of the ZSK MEGAcompounder
Operating Principle
Motor Gear Box Die HeadProcess Section
With Drive Powers from 10 kW up to 12 MW for Rates between 5 kg/h and 75 t/h
Modular Design
for Screw Elements and Kneading blocks
Pelletizing systems: Strand pelletizing
ExtruderStrand die
Waterbath
Air knife Pelletizer
ExtruderStrand die
Waterbath
Air knife Pelletizer
Profile extrusion
TimberTech Ldt. Ohio, USAwww.timbertech.com
• Timbertech composite lumber products helps create a more sustainable world
• TimberTech is low maintenance, safe, durable, and can even increase the value of your home
• Decking material is made of recycled wood and virgin polymers, 50/50.
• Located USA, Australia, Scandinavia, UK, Spain, France, …..
UPM Kymmene, Finlandhttp://www.upmprofi.com/Pages/default.aspx
• UPM Profideck made of residue from
labels
• Made in Finland, Germany, USA
http://www.globalhemp.com
Eric Pollitt
Production steps of natural fiber composites
for automotives
Pictures: Daimler
Automotive applications Daimler
Compression moulding (Daimler)
• Vacuum Infusion (VI)
• Resin Transfer Molding (RTM)
• Structural-Reaction Injection
Molding (S-RIM)
• Long fibres (even orientated)
• Low processing temperatures
• Good adhesion with thermoset
resins
• Better properties compared to
thermoplastics
• More expensive compared to
thermoplastics
Liquid composite molding
Vaccuum Infusion (VI)
• Dry fibres are placed in a mold
• The fibres are covered with a flexible bag and consolidatedusing vacuum
• The thermoset resin is infused
(UPE, epoxy, vinyl esters)
• Curing
• Fibre content will depend onthe fibremat structure
• Long processing time
• Large parts: automotives, boats
• Small to medium size series
Biocomposite snow board made of flax,
cashew and coke bottles
University of Sheffield's Advanced
Manufacturing Research Center (AMRC)
Bio based nanocomposites
Toyota
Renewable nanofibers or crystals as
reinforcements or additives in polymers
Interesting properties
−High mechanical properties
−High thermal stability
−Large surface area
−Bio-compatible
−Light weight
−Optically transparent
−High water binding capability
Future products: vehicles, medical,
cosmetic, textile, sport, electronic,
packaging applications
Green racing
Cellu Comp, Carrot Stix™
www.cellucomp.com
Hierarchical structure of wood
• Soft wood fiber, diam 20-30 m, length 2-5 mm
• Nanofibers, diam <100 nm, length > m
• Crystallites, width < 5 nm, length < 300 nm
• Mechanical properties increases with decreased size
• Softwood = E-modulus about 12 GPa and strength 100 MPa
• Wood nanocrystals = E-modulus about 140 GPa and strength 10000 MPa
Examples of bionanofibers and nanocrystals
Cellulose nanofibersCellulose nanocrystals Bacterial cellulose Collagen nanofibrils
Cellulose crystals/whiskers originate from wood, plants or crops,
width ~ 5 nm, length >200 nm depending on the source
Cellulose fibers originate from wood, plants, crops or bacteria
width around 100 nm, length up to µm scale
Collagen fibrils orginate from animal sources, width 50-500 nm
length up to mm scale
Preparation of bionanocomposites with good
mechanical properties
Fiber laminate
• Nanofiber network (sheets) are impregnated with a polymer resin
• High nanofiber content
• Long processing time (several days)
• Difficult to impregnate the dense network
• Liquid resin with low viscosity
• High mechanical properties can be reached
• High transparency
• Restricted to flat shape
Hiroyki Yano, Kyoto, Japan
Impregnation of cellulose nanofiber network
Dried network
from acetone
Dried network
from water
Nanocomposite laminate properties
Jonoobi et al. submitted to Composites part A
Materials E-Modulus
(GPa)
Strength
(MPa)
Max strain
(%)
CNF network 1.4 + 0.2 23 + 1.3 2.6 + 0.3
CAB 1.4 + 3.0 29 + 0.5 3.6 + 0.4
CNF/CAB 6.5 + 0.7 71 + 1.0 3.9 + 0.3
Melt compounding
Feeding of nanocrystals/fibers in to the extruder is a challenge
Dry feeding
Masterbach with high
nanocellulose content
Diluted during extrusion
Liquid feeding
Fibers/crystals are
dispersed in a liquid
Removal liquid
Degradation the polymer
Freeze drying and granulation
+
Nanocellulose fibers and crystals, thermplastic matrix
Content is low < 10%
Industrial process
Possible to injection mould
Different shapes are possible
Motor
Feeding
Heating and Mixing
Nanocellulose and composites
• Transportation (car, boat, train)
• Advanced composite materials
• Films & coatings
• Packaging products
• Spun fibers and textiles
• Additives for paint, glue & lacquer
• Optical components ex. computer
screen
• Electronic uses ex. batteries
• Bone and ligament replacement
• Hydrogels & aerogels
• Construction materials
• Additives in food and cosmetics
• Separations membranes
More information
Internet; WPC, biocomposites,
bionanocomposites etc.
Books:
• Wood polymer composites, Processing
properties and applications; K Oksman
and M Sain 2008
• Cellulose nanocomposites Processing,
properties and applications, K Oksman
and M Sain, 2006
• Engineering Biopolymers 2007
• Handbook of Green Materials, Oksman et
al. 2014
• Articles
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