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