Maria WLADYKA-PRZYBYLAKKrzysztof BUJNOWICZ

Institute of Natural Fibres and Medicinal Plants, Poznań, Poland

NATURAL FIBRES REINFORCED POLYMER COMPOSITES

Introduction

Composite is a material that contains

at least two different components,clearly separated one from another anduniformly filling its volume, produced in

order to create particular properties.

matrix

fiber

Introduction (2)

Lignocellulosic natural fibres are an excellentraw materials for production of wide range ofcomposites for different applications.

The interest in using natural fiber such asdifferent plant fiber as reinforcement inpolymers increased during last years.

flax

sunn hempCrotalia junceaL.

hemp

kenaf

urena

jute

mestaramieroselle(karkadeh)Isora

bast

pineapplebananasrew pineabaca(manila)curaua

sisalhenequen

agaves

cabuja

african palmdata-palm

palm

leaf

cottonkapokcoir

seed

coconut

fruit

hardwoodsoftwood

wood

wheatoatbarleyricebamboobagassereedcornraperyeespartoelephant grasscannary grass

grasses and reeds

Plant fibers - cellulose fibers

Natural Fiber and Fibrous raw materials for reinforcing Composites

They are widely used for different applications as constructions, furnishings and transportation

Building industry –conventional boards, insulatind boards, flame retardant composites

Furniture industry – conventional boards, flame retardant composites, non-wovens

Floor coverings – New Linoleum

Marboleum®

The natural vegetable fibres in different car structure elements of Daimler-Benz

Source: K. Bledzki, 1997

Bumper, Engine shield

Rear shelf

Roof

Sun shields

Upholstery, Door covering (racks), cover, electronic device

Wheel shield

Cellulose-polymer composite

soon in every car !

Natural Fibers Reinforced Polymers

– The interest in natural fiber reinforced polymer composite materials is rapidly growing both in terms of industrial applications and fundamental research.

– They are renewable, cheap, completely or partially recyclable and biodegradable.

– These fibers are incorporated into a matrix material such as thermosetting plastics,

thermoplastics or biopolymers.– The use of lignocellulosic materials in the form

of fibres or particles results not only in a considerable increase in biodegradability of a composite but also changes its properties, including flame retardancy characteristic.

Advantages of Composites Containing Natural Vegetable Fibers

They are environmentally friendly materials at the stage of production, processing and waste.

Environmentally friendly production of natural vegetable fibers - annual renewability and lower energy inputs in production per unit.

Commonly known processing methods.

Properties comparable to those of materials reinforced with glass fiber.

Better elasticity of polymer composites reinforced with natural fibers, especially when modified with crushed fibers, embroidered and 3-D weaved fibers.

They display acoustic insulation and absorb vibrations and large quantities of energy when subjected to destruction.

Lower density of polymer composites reinforced with natural fibers than those reinforced with glass fiber.

The price of polymer composites reinforced with natural fibers is from two to three times lower than that of polymers reinforced with glass fiber.

Natural vegetable fibers can be applied to the reinforcement of the natural polymers such as starch, lignin, hemicellulose and India-rubber and the material obtained in this way is 100% biodegradable.

Reaction to fire of composites based on lignocellulosic fibres is much more beneficial comparing to polymers – significant reduction of heat release rate

Matrixs of natural fibre reinoforced composites

phenolic PFepoxy EPpolyester SPpolyimide PIpolyurethane

PUR

thermosettingplastics

polypropylenepolyamidepolyethylenepolystyrenepolyvinylchloride

thermoplastics

india-rubbermodified

starchpolylactidecellulose

esterstanninpolyhydroxy-butiric acid

rubber&natural polymers

Polymers

These modern composites can be manufactured by classical methodssuch as extrusion and vacuum molding but also by pultrusion.They will be used in new lighter constructions and air transport. Thecomposites will show other features like current conductivity andsurface self cleaning.

Modification Methods

• Physical:– Surface fibrillation– Electric discharge, e.g. corona, cold plasma treatment

• Physico-chemical:– Mercerization, Acetylation

Fiber–OH + NaOH Fiber–O–Na+ + H2O

In Sweden, a continous

process of acetylation has been developed. The pilot plant for wood fibre or particles acetylation of capacity 500 kg/h is jointly owned by A-Cell and GEA Evaporation Technology AB, and located in Kvarntorp.

Modification Methods

Grafting copolymerization with:

Polypropylene-maleic anhydride (MAPP)

Vinyl monomer

Acrylonitrile

Methyl methacrylate

Styrene

Chemical Modification Methods

HO

C

C

O

O

C

C

HO

H2

HC

PPCHAIH

O

C C

C CC

H2

H

O

O

+ H2O OH

OH+ O

O

O

C

C

C

CC

H2

H

O

O

O

O

O

O

O

O

O

C C

C

C

CC

C

C

C

C

H H

H2

H

H2

H

cellulosefiber

cellulose

fiber

cellulosefiber

the activation of copolymer by heating

(t=170oC) before fiber treatment

esterification

of cellulose

Treatment with maleated polypropylene

• Silanization with organosilanes

Silane is a chemical compound with chemical formula SiH4.

(R1O)3 – Si – R2 – Xwhere R1O – hydrolyzable alkoxy group, and X- functional organic group

Chemical Modification Methods

TESTING METHOD

Cone calorimeter method - Standard ISO 5660

Conditions of the test:

specimen position: horizontal

heat flux: 35 kW/m2

spark igniter was used

scan: 5 s

The composite materials were tested in anATLAS cone calorimeter to obtain their heatrelease rate (HRR) and smoke evolutioncharacteristic.

What Cone Calorimeter Determines?

After test, the reduce program calculates the following parameters:

Heat Release Rate* (HRR) [kW/m2]Average HRR after 1, 3 and 5 minutes from ignition, and until the end of testPeak HRR (at time)

Total Heat Released (THR) [MJ/m2] Effective Heat of Combustion (HOC) [MJ/kg]

Average HOC during full time of test

Mass Loss Rate* (MLR) [g/m2s]Average MLR, taken for scans after 10% of total mass loss and before 90% of total mass loss has occurred

Specific Extinction Area (SEA) [m2/kg]Average SEA during full time of test

CO and CO2 Production [kg/kg]Average CO and CO2 yield, taken for scans after 10% of total mass loss and before 90% of total mass loss has occurred

* Predicted values of these parameters are displayed during test on the screen

Thermal Stability of Natural Fibers

Heat Realase Rate Heat Flux 35 kW/m2

with spark igniter

0306090

120150

0 100 200 300time [s]

HR

R [

kW

/m2 ]

cotton curaua abacahemp cabuya flax

Heat Realase Rate Heat Flux 35 kW/m2

without spark igniter

0306090

120150

0 100 200 300time [s]

HR

R [

kW

/m2]

cotton curaua abacahemp cabuya flax

in acc.Cone Calorimeter test ISO 5660 at heat flux of 50 kW/m2

Flammability some Polymersin acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2.

0

200

400

600

800

1000

1200

1400

1600

1800

0 30 60 90 120 150 180 210 240

Time [s]

HRR

[kW

/m2 ]

PP

PE

PLA

Flammability of Lignocellulosic- Polymer Composites

Polypropylene – Natural Fibres Composites

Materials

• Isotactic polypropylene (PP) Malen F-401; density 0,9g/cm3; MFI index 2,4-3,2g/10min and tacticity 95%

• Natural fibers – unmodified flax fibers, length 2-4 mm

• Hemp and flax shives unmodified and FR modified 1-2 mm – 30%

Flammability of Lignocellulosic- Polymer CompositesPolypropylene - Flax Fibres Composites comparison with PP

Heat release rate

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 60 120 180 240 300 360 420 480

Time [s]

HRR

[kW

/m2]

PP pure

PP+flax fibres 7.5%

PP+flax fibres 12.5%

PP+ flax fibres 20%

PP+ flax fibres 30%

in acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2.

Mass loss rate [MLR] of Lignocellulosic- Polymer CompositesPolypropylene - Flax Fibres Composites comparison with PP

0

5

10

15

20

25

30

35

0 60 120 180 240 300 360 420 480

Time [s]

MLR

[g/s

*m2]

PP pure

PP+flax fibres 7.5%

PP+flax fibres 12.5%

PP+20% of flax fibres

PP+30% of flax fibres

in acc. Cone Calorimeter test ISO 5660 at heat flux of 35

kW/m2.

Flammability of Lignocellulosic- Polymer CompositesPolypropylene - Flax Fibres Composites comparison with PP

0

10

20

30

40

50

60

70

80

90

100

110

120

Total HR

[MJ/m2]

Ave HOC

[MJ/kg]

Ave MLR

[g/s*m2]

IT [s]

PP pure

PP+flax 7.5%

PP+flax 12.5%

PP+flax 20%

PP+flax 30%

Total HR, Ave HOC, Ave HOC, Ave MLR, ITin acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2

Smoke production as extinction coefficient (EC) of Polypropylene - Flax Fibres Composites comparison with PP

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

5

0 60 120 180 240 300 360 420 480 540 600

Time (s)

EC

(1

/m)

PP pure

PP+flax fibers 7,5%

PP+Flax fibes 12,5%

PP+Flax fibers 20%

PP+ flax fibers 30%

Comparison of heat release rate (HRR) composites based on PP and different plant fibres (content 30% by weight)

0

150

300

450

600

750

900

1050

1200

1350

1500

0 60 120 180 240 300 360 420 480 540 600

Time [s]

HR

R [

kW

/m

2]

PP

PP + Flax

PP + Hemp

PP + Jute

PP + Coconut

in acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2

Comparison of heat release rate (HRR) composites based on PP and different and FR protected Flax and Hemp Shives

in acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2

0

200

400

600

800

1000

1200

1400

1600

0 200 400 600 800 100

Time [s]

HR

R [

kW

/m2

]

PP

PP-Hemp 30%

PP-FRHemp30%

0

200

400

600

800

1000

1200

1400

1600

0 100 200 300 400 500 600 700

Time [s]

HR

R [

kW

/m2

]

PP

PP-Flax 30%

PP-FR Flax30%

Comparison of IT, Total HR, Ave HOC, Ave MLR, composites based on PP and different and FR protected

Flax and Hemp Shives

0

50

100

150

200

250

IT [s] Total HR

[MJ/m2]

Aver HOC

[MJ/kg]

Ave MLR

[g/ms2]

PP

PP-flax 30%

PP-FR flax 30%

0

50

100

150

200

250

IT [s] Total HR

[MJ/m2]

Aver HOC

[MJ/kg]

Ave MLR

[g/ms2]

PP

PP-hemp 30%

PP-FR hemp 30%

in acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2

Flammability of

Polyethylene - Flax Fibres Composites

Materials:

• Polyethylene (low density Malen E GGNX 23DO22) PKN Orlen in Plock, Poland

• Short flax fibers (2-3m) 10%, 15 % by weight

Flame Retardancy of Polyethylene - Flax Fibres Composites comparison with PE

0

400

800

1200

1600

2000

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Time [s]

HR

R [

kW

/m2]

PE

PE+10%Flax

PE+15% Flax

Heat release ratein acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2

Comparison of IT, Total HR, Ave HOC Polyethylene -Flax Fibres Composites with PE

172

146 131

0

20

40

60

80

100

120

140

160

180

THR

[MJ/

m2]

PE PE+10% Flax PE+15% Flax

44,9 41,1 40,7

38

39

40

41

42

43

44

45

HOC

[MJ/k

g]

PE PE+10% Flax PE+15%Flax

11239 36

0

20

40

60

80

100

120

Tim

e to

ign

itio

n [

s]

PE PE+10%Flax PE+15%Flax

Total heat released THR Effective heat of combustion (HOC)

Time to ignition

Flame Retardancy of Poly(lactic acid) PLA – Flax, Hemp Fibres Composites comparison with PLA

Materials

• PLA Hycail HM 1010

• Unmodified flax and hemp fibers, length 1-3 mm, 10% by weight

• Flax and hemp fibers after mercerization process, length 1-3 mm, 10% by weight

• Acetylated flax fibers, length 1-3 mm, 10% by weight

Comparison of heat release rate (HRR) from composites based on PLA Resin with hemp fiber

and chemical modyfication hemp fiber

0

100

200

300

400

500

600

0 40 80 120 160 200 240 280

Time [s]

Hea

t R

ele

ase

d R

ate

[k

W/m

2]

PLA

PLA+Hemp

PLA+Hemp Mercer

PLA+Hemp Acetyl

in acc. Cone Calorimeter test ISO 5660 at heat flux of 35 kW/m2

Comparison of heat release rate (HRR) from composites based on PLA Resin with flax fiber and

acetylation flax fiber

0

100

200

300

400

500

600

0 40 80 120 160 200 240 280

Time [s]

Hea

t R

ele

ase

Ra

te [

Kw

/m

2]

PLA

PLA+Flax

PLA+Flax Acetyl

Conclusions

1. Nowadays a lot of attention is paid toenvironmentally-friendly materials. Thisresulted in growing interest in naturallignocellulosic materials and compositesbased on them.

2. Lignocellulosic Composites are much moresafety during fire than man-made polymersbecause of lack of dangerous melting and

less toxic gases and smoke production.

3. Interesting results were obtained while studyingpure PP, PE and that with an admixture of flax, hemp, fibres and shives.

Heat release rate HRR and mass loss rate MLR curves show that thermal decomposition and combustion of the mentioned samples occur in a different way.

The addition of fibres, specially in amount above20% resulted in an increase in flameretardancy of composite compared to PP, PE

alone.

Institute of Natural Fibres and Medicinal Plants

Wojska Polskiego 71 b

PL 60 630 Poznan

Tel: (+ 48 61) 822 48 15

Fax: (+ 48 61) 841 78 30

http://inf.poznan.pl

Thank you for your attention !