A new natural reinforcement for polymer composite materials: … Vuure, AW.pdf · 2019-08-02 · A...

A new natural reinforcement for polymer composite materials: Long Bamboo

fibres

Aart W. van Vuure, Lina Osorio, Eduardo Trujillo, Carlos Fuentes, Jan Ivens, Ignaas Verpoest

Department of Metallurgy and Materials Engineering,

Katholieke Universiteit Leuven

First; what do we call polymer composite materials?

Fibre: reinforcement

Impregnate

Polymer: matrix

COMPOSITE

Consolidate

Light but weak

Light, stiff & strong

Light but stiff & strong!

• Long fibres give better mechanical properties

• Fibres typically Glass and Carbon

2World Bamboo Congress, April 2012

Natural Fibres (and Bio-polymers): why?

3

Environmental reasons:

• Renewable resources

• Thermally recyclable, optionally biodegradable, CO2

neutral

• Natural fibres: Low energy consumption (low CO2 )

So: low “Carbon footprint”

0

20

40

60

80

100

120

140

lignocellulosicfibres

glass fibre carbon fibre

energy ( MJ/kg)

energy ( MJ/kg)mat

mat

World Bamboo Congress, April 2012

4

• Cost: often (potentially) low cost (not silk)

• Less abrasive

• Good specific mechanical properties (low density)

• Potential bio-compatibility for e.g. bio-medical applications

• Natural image, design aspects

• Others, like good acoustic & vibration damping, radar transparency, low CTE

Natural Fibres and Bio-polymers: why?

Specific tensile modulus E/rho (MJ/kg) for various fibres

0

20

40

60

80

100

120

140

Flax fibre Bamboofibre

Glass fibre Carbon fibre

Spec

ific

mod

ulus

(MJ/

kg)

Specific FLEXURAL modulus (E(1/3)/rho in N(1/3)m(7/3)/kg) for various fibres

0

0.5

1

1.5

2

2.5

3

3.5

4

Flax fibre Bamboofibre

Glass fibre Carbon fibreSpec

ific

bend

ing

mod

ulus

(N(1

/3)m

(7/3

)/kg)


Good vibrational damping: Flax/Carbon hybrid bicycle frame

ISO2631:WholeBodyVibration

5

Applications of bio-based composites; on the market

Museeuw/Lineo Flax-Carbonhybrid bike(JEC 2007);Prepregtechnology

Decathlon Artengo 820Flax/Carbon Fibre racket(prepreg Lineo)

Mixed NF – PPCar interiors

WoodPolymerComposites(WPC’s)e.g. deckings


Applications of bio-based composites; prototypes

NPSP front-end train• flax-UP composite• vacuum injection• ~500 kg lighter than steelconstruction!

Toyota 1/X concept car (420 kg!):• Carbon Fibre frame• Roof of kenaf/ramie fibre composite

• heat and sound insulation• lightweight

Motive Kestrel electric vehicle•Launch 2012 in Canada?•Bio-based composite body

Prototype flax/PP (TU Delft)


Natural Fibres, Quantities

Estimated annual production, in millions of tons:

Wood 1750

Steel 1000

Plastics/polymers 200

Composites (polymer) 5-10 mainly glass fibre composites

Glass fibre 2-4 (at 42% in composites)

Carbon fibre 0.050 (= 50,000 tons)

Synthetic fibres 30

Natural fibres 27 (large part cotton)

Flax fibres ~ 1.0

WPC 1.2

Plant fibre in composites 0.040 in automotive applications Europe


Natural Fibres

PLANT / Lignocellulosic

FIBRES

Wood Stem/Bast

FlaxJute

HempKenafRamie

Leaf

SisalAbaca

PineappleBananaFique

HenequenPalm

Seed/Fruit

CottonCoconut

Grass

BambooRice

ANIMAL FIBRES (protein)

SoftwoodHardwood

SilkWool


Main challenges for Bio-based Composites

1)

Fibre

properties:* Understanding structure (morphology) – mechanical property relationships

* Fibre off-axis properties: low transverse and shear properties

** Improve internal interface between elementary fibres

* Moisture sensitivity: Make fibres more hydrophobic? / seal them off (interface)

2) (Fibre) Processing• Extraction, yarn processing, preforming and prepregging

3) Fibre-matrix Interface:• Improving wetting and adhesion (surface energy matching)

4) Environmentally friendly matrices:* Biodegradable or Bio-based


Bio-based Composites; Natural fibre properties; examples

Silk Composites have excellent falling weight impact performance!

Patent: WO 2007-110758 (with Hermès)


MatricesClassification of matrices:

* Thermoplastic (TP) and thermoset resins (TS)

• Research on renewable matrices is relatively recent, especially for bio-thermosets

Examples of polymers Natural polymers:(renewable)

BIO-BASED

polymers (renewable feedstock, synthesized!):

“Synthetic” petroleum based polymers

Biodegradable Lignin PLAPHA, PHBStarch

PBSPCLPVA

Non-biodegradable Cashew nut shell resin (CSNL)

Furan resinVegetable oil -PUR (polyol)AESOEthanol based PESome nylons (PA-11)

Most well-known polymers:* PP, PE, nylons, etc.* Epoxy, UP


Bio-based Composites; Developing environmentally friendly matrices

Development of renewable gluten based bio-polymers:

• Improvement of toughness & rheology

• Patent on thiol-based modifiers (WO 2004/029135)

• So far 50% improvement in strength and strain to failure (approaching epoxy)

Gluten

ResinBio-based

Polymer or CompositeMaterial

Controlled-releaseNitrogenFertilizer

Wheat

agriculture

Starch

industrialprocessing

recycling

chemical or(bio)catalyticmodification

polymerprocessing

Compost

composting

Thiol-terminated star-branched modifiers:Crosslinking + phase separation?


Fibre processing research; Effect of twist on FLAX UD-composite stiffness (CELC)

-

35 % !!

Back-calculatedfibre stiffness(matrix=epoxy)


Bio-based Composites; Fibre

processing

80‐100%

~50% !

Research in cooperation with CELC

Combined effect of twist and crimp on composite modulus


Bio-based Composites; Paper honeycomb panels

Applications of ‘Torhex’ cardboard honeycombs; sandwich panels with NF composite skins

www.econcore.com


Large Projects at SLC - BioComposites

•Cornet Nature Wins (with Centexbel and ITA Aachen)

Thermoplastic bio‐composites, flax/hemp + PLA

•

Mixed yarns & textiles / non‐wovens

•

Consolidation and thermoforming

•TIS Change2Bio (with VKC and Centexbel)“Renewable polymers – important element to develop the bio‐economy”


Bamboo Fibre Composites

Culm with vascular bundles Technical

fibre(s)

• Bamboo fibres have excellent

mechanical properties

• Specific properties comparable to glass fibre

• Bamboo can grow to 20 m in 6 months

• Can fix 50-60 tons of C/ha.year

• Challenge is to extract technical fibres

Elementary fibres


Bamboo Fibre processing

150

250

350

450

550

650

750

850

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Extraction method

Stre

ngth

(MPa

)

Mechanical(rolling mill machine)

Chemical extraction(in some cases

mechanical process is required)

Steam explosion

Mechanical process(in some cases chemical process is required)

KULeuven process

Loop test

Bamboo Fibre

Extraction

19

Bamboo Fibre properties

Single fibre tensile tests;

Corrected for system compliance

* E(extrapolated) ~ 44 GPa

New developments: * use of Digital Image Correlation (camera extensometer)

* Fibre bundle tests (dry + impregnated)

* Study of off-axis properties

E-modulus as f(1/test length), Single bamboo fibre testing

05

1015202530354045

0.00 0.05 0.10 0.15 0.20 0.251/test length (1/mm)

E-m

odul

us (G

Pa)


Bamboo Fibre morphology (Lina Osorio)

4

3

Bamboo wallLiese, W., 1998Vascular bundleFibre

bundle

Bamboo culm Cross section

Elementary fibres

Vascular bundles have higher concentration towards the outside of the culm


Bamboo Fibre morphology

Most elementary fibres seem to havea simple 2 layer structure

Next: Measurement of off-axis properties (tests on composites)

Primary layer with 90° orientation;from fracture surface

Secondary layer with 0° orientation;After etching away primary layer

5 μm5 μm5 μm


Continuous UD prepreg

Discontinuous UD prepreg

Discontinuity of the fibre

Length of internodes

(± 25 cm)

Node

Internode

Bamboo fibre process development(Eduardo Trujillo)

Problem statement

UD prepreg with discontinuous fibres; continuous process?

UD bamboo fibre-polypropylene tape


Technical fibre ~100 – 200 μm

Elementary fibre ~10 μmWith micro/nano fibrils:

Microstructure Surface

Chemical composition

Topography

Wetting

vapour

liquid

Micro balanc

e

F (μN)

R

Fibre

and matrix

Molecular kinetic theory

Equilibrium contact angle

SEC theories

Owens/Wendt

Dsv

Psvsv

Acid/base

cos1, iiL =)θ+(γ

)(2 ,,, SiLSiL

LWS

LWiL

Adhesion Improvement

Approaches:1. Make a good match

with untreated fibre:

Polyvinylidene fluoride (PVDF)

2. Treat the surface to get a good match:

Chitosan layer, Silanes

Interface Characterization

Streaming Potential

Micromechanical test: Pull-out tests

Flexural test: Transverse

3 point bending test

X-ray photoelectronspectroscopy (XPS)

AFM

Profilometer

Primary wall: 90°

orientation

Secondary wall: 0°

orientation

Understanding and improving the fibre-matrix interface;a combined physical-chemical-mechanical approach(Carlos Fuentes)

Bamboo fibre surface analysis

0

10

20

30

40

50

60

70

80

0.0 0.2 0.4 0.6 0.8 1.0

C1/C (%)

O/C

O/C vs C1/C

Non‐autoclave treated bamboo

Autoclave treated bamboo

Theoretical Cellulose

Theoretical milled wood Lignin

Protobind 1000 Granit Lignin

Cellulose

Lignin

Measured Lignin

XPS results; courtesy C. DuPont, UCL

Extracted bamboo fibre surface seems to be covered with lignin


Interface studies; Bamboo fibre composites

Bamboo fibre UD composites

R2 = 0.6963

0

5

10

15

20

25

40 45 50 55 60 65 70 75 80

Work of physical adhesion (mJ/m2)

Tran

sver

se 3

PB

str

engt

h (M

Pa)

Matrix: PP and PVDF (+ some treatments)

Results of Surface Energy Component matching; Effect of Physical Adhesion in thermoplastic composites


Addition of chemical adhesion

Transverse 3 point bending strength for UD Bamboo-epoxy

15

20

25

30

35

40

45

0 1 2 3 4 5 6Alkali treatment (%) (20 min)

T3PB

(MPa

)


Work of Adhesion versus Interface strength for coir composites

Chemical bonding dominant Physical adhesion

U = Untreated

T = Alkali treated


Bio-based Composites; Fibre properties

Flax fibre property improvement* Fibre Treatment to Reduce Direct and Indirect Moisture Uptake

* Fibre Treatment to Improve internal fibre strength


Bamboo Fibre Composite performance

COMPOSITE longitudinal flexural tests

Efficiency factor = measured property / theoretical property based on fibre properties

.... ..

Force

..

Efficiency factors in longitudinal flexural test

0

10

20

30

40

50

60

70

80

90

100

Efficiency factor strength Efficiency factor modulus

Effic

ienc

y fa

ctor

(%)

PPPVDFepoxy

+ Transverse 3 PB strength values

15 MPa

15 MPa23 MPa

33 MPa23 MPa

33 MPa

30


Moisture resistance Bamboo fibres Moisture uptake of bamboo fibre at 23oC (from dry

condition)

02468

1012141618

0 20 40 60 80 100

Environmental relative humidity (%)

Moi

stur

e up

take

(wt%

)

Fibre moisture uptake,

Absorption isotherm

Moisture uptake is intermediate to literature data for (solid) lignin and cellulose

Diffusion coefficient [m2/sec]

Bamboo 1.04 x 10-10

Flax 1.25 x 10-8

31

Moisture effects on Bamboo fibres


Thermal degradation Bamboo fibre composites

Single fibres: Degradation starts around 170°C in normal atmosphere

Flexural strength and failure strain for UD bamboo fibre/thermoplastic composites at different processing

temperatures

020406080

100120140160180200220

0 0.5 1 1.5 2 2.5 3

Strain at maximum strength (%)

Stre

ngth

(MPa

)

PP/BF 175°C

PP/BF 185°C

MAPP/BF 170°C

MAPP/BF 180°c

.... ..

Force

..


Concluding (Bamboo Fibre Composites)

• A promising fibre extraction process was developed for Bamboo Fibres• Next processing development is cleaning, stretching, aligning and prepregging• Most elementary fibres have predominantly 0 degree nanofibril orientation, combined

with an outer wrap of 90 degrees• Extracted bamboo fibre seems covered by lignin• Surface energy component matching allows improving physical adhesion; so far good

results with PVDF• There is a clear correlation between interface strength and UD longitudinal strength• Efficiency factors for epoxy reach 95% for modulus and 80% for strength• Moisture uptake is as expected intermediate to solid cellulose and lignin• Fibre strength and modulus are hardly affected by moisture; strain to failure is

affected (plasticisation)


Thanks for your attention!

JEC 2012 Tradeshow in Paris: KU Leuven - SLC booth


CompositesWeek@Leuven16-20 September 2013

The Composite Materials Groupof the Department of Metallurgy and Materials Engineering (MTM) of the

Katholieke

Universiteit

Leuven

(Belgium)cordially invites you to the

Three one-day symposia

on : •nano-engineered composites,

•designing with composites •bio-based composites

+the TEXCOMP 11

conference on textile composites

www.mtm.kuleuven.be/Onderzoek/Composites/Composietenwww.texcomp10.com

http://www.mtm.kuleuven.be/Onderzoek/Composites/Composieten

http://www.texcomp10.com/

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A new natural reinforcement for polymer composite materials: … Vuure, AW.pdf · 2019-08-02 · A...

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