Intercalation/Exfoliation and Performance of Clay-Poly(lactic acid) Nanocomposites

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Intercalation/Exfoliation and Performance of Clay-Poly(lactic acid) Nanocomposites

Ton That, Minh Tan; Denault, Johanne; Patenaude, Éric; Leelapornpisit, Weawkamol.

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Intercalation/Exfoliation and Performance of

Clay-Poly(lactic acid) Nanocomposites

M-T. Ton-That , W.Leelapornpisit, J.Denault

Bioplastics 2006

Montreal, Quebec, Canada

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Presentation outline

 Introduction

 Objectives

 Melt compounding; effect of clay chemistry and PLA structure  Characterization  X-ray  SEM  TEM  Mechanical properties  Tensile tests  Impact  HDT  Conclusions  Future works

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Green Processing of Strong, Lightweight Polymer

Foams from Renewable Resources

Value: 1.7 M$ Duration: 3 years

NRC Partners: IMI and ICPET

Sponsor: Climate Change Technology and Innovation (PERD/OERD)

Foam manufacturing from bio-based (PLA, PHA…)

polymer nanocomposites

In Summary

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Our Responsibilites

Respond to our needs for materials in the 21

st

_century

 Environmental issues and economic concerns due to limited oil supply

 To cope with limitation of resources supply

 Synthetic polymers are highly durable materials (200-500 yrs) mostly used in short-term applications

 Non-biodegradable plastic represent 11% of the municipal solid waste in USA (data 2001).

 Incineration of synthetic plastic produces CO₂ contributing to global warming

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Why Biopolymer ?

Biopolymers are now available at large scale and reasonable

cost.

 PLA example

 In US, NatureWorks has a 300 million pound PLA plant

with a cost of 1U$/pound.

 NatureWorks is able to supply large-scale company like

Coca-Cola, Dunlop Pacific, etc.

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Biopolymer Advantages

 Made from renewable ressources

(sustainable)

 Biodegradable and recyclabe

after service

 PLA advantages

 High clarity and gloss  High stiffness

 Easy to process on standard equipment

 Good film forming properties

 Properties similar to Polystyrene  Good taste and aroma barrier  Cost competitive to PET

From R. Auras et al, Macromol. Biosci., 4, 835 (2004)

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PLA Applications

 Medical field

 Drud delivery systems  Healing products

 Surgical implant devices

 Packaging materials

 Food containers  Agriculture  Waste bags

 Non-woven structure

 Filtration  Hygiene products  Protective clothings

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Biopolymer Applications

Henry Ford in 1937

Dream of Henry Ford in 1930

 ‘’Growing a car like a crop’’

 Use soy-based polymer for knobs and body panels

 Water absorption problem causes excessive body panels warpage

 Was replace by synthetic polymer after the World War II because

of economy and durability

 Now such durability becomes

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PLA: Synthesis and

Structure

93%+ L-LA = Semi-Crystalline PLA 50-93% L-LA = Amorphous PLA NatureWorks Manufacturing Process:

D-LA Content (wt%) 0 2 4 6 8 Me ;ltin g T emp era tu re (°C ) 135 140 145 150 155 160 165 170 175 C ry sta llin ity (% ) 0 10 20 30 40

From R. Auras et al, Macromol. Biosci., 4, 835 (2004) and G. Schmack et al., JAPS, 91, 800 (2004)

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Challenges with PLA

 Acceptance in the market place

 PLA must be competitive on a cost-performance basis

 Property limitations

 High density 1.25 g/cc  Low Tg (50°C) and HDT

 Low crystallinity and slow crystallization  Brittleness

 Heat resistance lower than PET  High moisture absorption

 Limited barrier to moisture and gases (O₂and CO₂)

 Nanotechnology and foam process can upgrade PLA

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Objectives

 Develop formulations of Poly(lactic acid)

Nanocomposites by melt compounding technologies

 Optimize processing

 Control the micro-nanostructure

 intercalation vs exfoliation

 Maximize performance

 Minimize cost

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PLA Nanocomposites

Materials and Processing

Nanoclays

Cloisite Na+ (Southern Clay Products) Cloisite 20A (Southern Clay Products) Cloisite 30B (Southern Clay Products) Nanomer I30E (NanoCor)

Conditions

Haake conical counter-rotating TSE N= 100 rpm T_melt = 190-230°C t = 5-20min Polymer PLA 2002D, (NatureWorks) T_m=148°C  5-7% D-LA (amorphous)

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PLA Nanocomposites

Structure -XRD

Cloisite 30B

MT2EtOH: methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium 2 0 2 4 6 8 10 12 Int ensit y (k cps ) 0 1 2 3 4 Neat PLA 2% Cloisite 30B 2% Nanomer I30E 2% Cloisite 30A Cloisite 30B provides a better intercalation and exfoliation (asymmetric peak) because of the

hydroxyl group in the intercalant

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PLA Nanocomposites

Structure - SEM

Cloisite 30B

MT2EtOH: methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium

Cloisite 30B provides a very good

micro-dispersion even in the low shear rate of the mini-compounder

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PLA Nanocomposites

Structure - TEM

Cloisite 30B

MT2EtOH: methyl, tallow, bis-2-hydroxyethyl, quaternary

ammonium

Cloisite 30B provides a fairly good intercalation and exfoliation even in the low shear rate of the mini-compounder

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PLA Nanocomposites with

a Twin-screw Extruder

 Materials

 Clay: Cloisite 30B (SCP)

 PLA 8302D (PLA-A-amorphous) (9.85% d-Lactic acid)  PLA 4032D (PLA2-C-crystalline) (1.40 % d-Lactic acid)  Melt process  Twin-screw extruder  Side-feeding  200º_C  L/d = 40  200 rpm  Injection molding  200º_C PLA Clays

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 Only very lightly difference in term of intercalation

 At 2wt% clay, exfoliation took place in both PLA matrices  But better exfoliation for

amorphous PLA 0 4000 8000 12000 16000 20000 1 3 5 7 9 2o In te n s it y ( c o u n ts ) Cloisite 30B Masterbatch NC-10wt% NC-4wt% NC-2wt% 1.82 nm 3.46 nm Amorphous 0 4000 8000 12000 16000 20000 1 3 5 7 9 2o In te n s it y ( c o u n ts ) Cloisite 30B Masterbatch NC-10wt% NC-4wt% NC-2wt% 1.82 nm 3.12 nm Crystalline

XRD Analysis

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Annealing effect

Clay structure

 Annealing seems to decrease the intercalation-exfoliation of clay and more evidence in the PLA crystalline systems as a result of crystallization Amorphous (Annealing at 90oC ) 0 2000 4000 6000 8000 10000 1 3 5 7 9 2 (o) In te n s it y ( c o u n ts ) 2wt%-A2wt%-A-90o-1d 2wt%-A-90o-3d 4wt%-A 4wt%-A-90o-1d 4wt%-A-90o-3d Crystalline (Annealing at 90oC ) 0 2000 4000 6000 8000 10000 1 3 5 7 9 2o In te n s it y ( c o u n ts ) 2wt%-C2wt%-C-90o-1d 2wt%-C-90o-3d 4wt%-C 4wt%-C-90o-1d 4wt%-C-90o-3d

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 Annealing leads to higher crystallinity

 Effect is more important in the low D content PLA; clay seems to favor the crystallization

Amorphous (Annealing at 90oC)

3000 5000 7000 9000 11000 13000 15000 15 16 17 18 19 20 2o In te n s it y ( C P s ) PLA-A PLA-A-90o-1d PLA-A-90o-3d 2wt%-A 2wt%-A-90o-1d 2wt%-A-90o-3d 4wt%-A 4wt%-A-90o-1d 4wt%-A-90o-3d

Crystalline (Annealing at 90oC )

0 10000 20000 30000 40000 50000 60000 70000 15 16 17 18 19 20 2o In te n s it y ( C P s ) PLA-C PLA-C-90o-1d PLA-C-90o-3d 2wt%-C 2wt%-C-90o-1d 2wt%-C-90o-3d 4wt%-C 4wt%-C-90o-1d 4wt%-C-90o-3d

Annealing effect

PLA structure

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Mechanical Properties

Amorphous PLA 50 55 60 65 70 75

PLA-A NC-A-2% NC-A-4% NC-A-10%

Tens

ile strength (MPa)

2000 3000 4000 5000 6000 7000 Tens

ile modulus (MPa)

Strength Modulus 80 90 100 110 120 130

PLA-A NC-A-2% NC-A-4% NC-A-10%

Flex ural str ength (MPa) 3000 4000 5000 6000 Flex ural modu lus (MPa ) Strength Modulus 10 15 20 25 30

PLA-A NC-A-2% NC-A-4% NC-A-10%

Notched Izod impa

ct (J/ m) 55 57 59 61 63 65 HDT ( o C) Impact HDT

 Clay improves strength and modulus and does not affect the impact and HDT

 At high clay concentration of 10%: loss in tensile and impact strength are noticeable

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Mechanical Properties

Crystalline PLA 50 55 60 65 70 75 PLA-C NC-C-2% NC-C-4% NC-C-10% Tens

ile strength (MPa)

2000 3000 4000 5000 6000 7000 Tens

ile modulus (MPa)

Strength Modulus 80 90 100 110 120 130 PLA-C NC-C-2% NC-C-4% NC-C-10% Flex ural str ength (MPa) 3000 4000 5000 6000 Flex ural modu lus (MPa ) Strength Modulus 10 15 20 25 30 PLA-C NC-C-2% NC-C-4% NC-C-10%

Notched Izod impa

ct (J/ m) 55 57 59 61 63 65 HDT ( o C) Impact HDT

 Similar observation as for amorphous systems:

 Clay improves strength and modulus and does not affect the impact

 At high clay concentration of 10%: loss in tensile and impact strength are noticeable

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Amorphous PLA

 Good exfoliation has achieved although very few multiple stacks remain (may be due to the imperfection of clay treatment or clay degradation)

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Crystalline PLA

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Summary and

Conclusions

 Cloisite 30B is the most appropriate commercial organo-clay for the fabrication of PLA nanocomposites by melt compounding

 Good exfoliation can be achieved with Cloisite 30B by

melt-compounding (but processing parameters play a very important role)  With the addition of less than 5wt% clay, strength and modulus of

the PLA matrix are improved why impact strength is not affected  Amorphous PLA seems to give better intercalation-exfoliation

structure

 However HDT is not improved

 Problem of clay-PLA interaction?  Intercalant degradation?

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Future work

 Optimize of the processing procedure to minimize

intercalant and PLA degradation and optimize clay-PLA

interaction

 Better understanding the crystallinity effect in the

intercalation/exfoliation and the mechanical performance

 Extrusion parameters

 Use more thermally stable intercalant

 Use of coupling agent if necessary

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Commercial nanoclays

• Southern Clay Products, Inc.

– MMT: 92.6 meq/100g – Intercalant:

• Cloisite 10A (2MBHT)

• Cloisite 15A, 20A (2M2HT) • Cloisite 35A (2MHTL8) • Cloisite 30B (MT2EtOH) • Cloisite 93A (M2HT)

MT2EtOH: methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium

2MBHT: dimethyl, benzyl,

hydrogenatedtallow, quaternary ammonium

2M2HT: dimethyl, dihydrogenatedtallow, quaternary ammonium

2MHTL8: dimethyl, hydrogenatedtallow, 2-ethylhexyl quaternary ammonium

M2HT: methyl,