Nanoclay/Polymer Composites for Improved Physical Properties

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Nanoclay/Polymer Composites for Improved Physical Properties

Underhill, Royale S.; Chapleau, Nathalie

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Defence R&D Canada • R & D pour la défense Canada

Nanoclay/Polymer Composites For Improved

Defence Research and

Development Canada Recherche et développementpour la défense Canada

Canada

Physical Properties

Royale S. Underhill1_{and Nathalie Chapleau}2 1_{Defence R&D Canada – Atlantic (Dockyard Lab (Atlantic))} 2_{National Research Council Canada – Industrial Materials Institute}

8 April 2009 2009 CF/DRDC International Defence Applications of Materials Meeting

Acknowledgements

• DRDC Atlantic – Mr. Irv Keough (DMA, DSC, TGA) – Mr. Gary Fisher (XRD, SEM) – Dr. Shannon Farrell • NRC – IMI – Ms. Manon Plourde (abrasion tests) – Mr. Yves Simard (compounding) – Mr. Michel Carmel

(XRD)

– Dr. Allison Nolting

(tensile tests)

(sheet casting and injection molding)

• NRC – IRC

– Dr. Joseph Su

(cone calorimetry)

Outline

• Future soldier requirements

• Nanoclay composites for improved functionality in

a lightweight product

• Experimental:

Sample Preparation

– Sample Preparation

– Composite Characterization

– Physical Properties

– Flammability

• Conclusions and Future Work

Soldier Systems Requirements

• A system that integrates all that s/he wears/carries.

• Future requirement to: – carry more, – utilize more technology, – withstand more extreme environments. • Multifunctional materials:

• Multifunctional materials: – lightweight, – enhance stealth, – ballistic protection, – CB resistance, – Power, – Durability, – Comfort.

Background – Clays

• Sheet-structure interspersed with water and cation layers – e.g., (½Na,Ca)_0.7(Al_3.3Mg_0.7)(Si₈O₂₀)(OH)₄·nH₂O • Layers swell (Smectite Clays)

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Background – Clay Nanocomposites

i

l

d

f li

d

• Conventional composite: 20-50% loading • Nanocomposite: 2-7% loading

microcomposite

(conventional)

intercalated

exfoliated

(nanocomposite)

Commercial Uses – Current

Main areas of use

• Automotive, Packaging

Improved properties

• Mechanical: – Dimensional stability

– Tensile strength, Modulus, Tear strength • Barrier:

– Improved O2, CO2, VOC, H2O(g)barrier

• Flame retardancy: – Dripping and charring • Other:

– Surface – smooth, hard – UV-stability – Rheology

Sample Preparation (1)

Polymer Clay Conc. (% wt)

Polypropylene (PP) (Profax 1274) None 0 Natural (Cloisite 15A) 2 4 Compatibilized Natural (Cloisite + Low MW PP) 2 4 Compare natural vs. compatibilized

Synthetic (Perkalite F100) 2 4 Polyamide-6 (PA) (a.k.a. Nylon 6) (PA1015B) None 0 Natural (Cloisite 15A) 2 4 Synthetic (Lucentite SWN) 2 4 Synthetic (Somasif ME100) 2 4 Compare aspect ratio 50 vs. 6000

Compatibilization

• To make a clay more oleophilic:

– Reaction with short chain polypropylenes.

Sample Preparation (2)

• Sheets were extrusion cast. • Dogbones were injection

molded.

Nanoclay Composite Characterization

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Composite Characterization: SEM

polypropylene + 4% natural clay

PP + Cloisite 15A A. Secondary e-image: – Variations in topography B. Back-scatter image: – Variations in atomic # 2m A.

• Fracture may have

occurred along clay

particles

2 m 2 m B. PP + 2 PP + 2 wtwt.% LDH.% LDH PP + 4 PP + 4 wtwt.% LDH.% LDH

Composite Characterization: TEM

polypropylene + synthetic clay

• Note the “clumps”

Defence R&D Canada • R & D pour la défense Canada 500 nm 500 nm 100 nm 100 nm PP + 2 PP + 2 wtwt.% LDH.% LDH PP + 4 PP + 4 wtwt.% LDH.% LDH

Composite Characterization: XRD

polypropylene

• Natural clay did not disperse well in PP, even when

compatibilizer was used. – Corroborates microscopy data

• Synthetic clay dispersed better than natural clay in PP. • Presence of peaks indicates intercalation; not exfoliation.

Composite Characterization: SEM

polyamide + 4% natural clay

PA + Cloisite 15A A. Secondary e-image: – Variations in topography B. Back-scatter image: 2m A.

– Variations in atomic #

• No variations in

back-scatter indicate that

the clay is well

dispersed.

2m

2μm

B.

Natural

(in situpolymerization)

Natural Synthetic

Composite Characterization: TEM

polyamide + 2% clay

Cloisite 15A 200 nm Cloisite 15A (commercial grade) 200 nm 200 nm 200 nm

Lucentite (SWN) Somasif (ME100)

Composite Characterization: XRD

polyamide

• Intercalation observed in polyamide + natural clay system. • Synthetic clay; d-spacing increases only 0.01 nm

• Micrographs and XRD suggest PA has better dispersion than

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Nanoclay Composite Physical Properties

Composite Physical Properties:

Thermal Gravimetric Analysis

• decomposition temperature: – PP1 (neat) = 456°C – PP + clay = 465°C

– PP2 (neat) = 463°C

+9°C

( ) – PP + syn. clay = 460°C

– PA (plain) = 441°C – PA + clay = 410°C

-31°C

-3°C

Composite Physical Properties:

Differential Scanning Calorimetry

• PP:

– No significant change when the amount of uncomp. nat. clay was varied in the composites. – When 4% comp. nat. clay was

added, crystallinity decreased and crystallization temperature (Tc) decreased 6°C.

– When synthetic clay was added, crystallinity didn’t change, but Tc increased 7°C.

• PA

– No significant change in melt or crystallization temperatures with the addition of clay.

Composite Physical Properties: DMA

• General trend is an increase in modulus with an

increase in clay loading.

• PP + comp. nat. clay composites tend to be stiffer

than their uncomp. counterparts.

Composite Physical Properties: Tensile

• Addition of clay increased both the max tensile stress and the

necking strength.

• Clay reduced ductility. • There was a strain rate dependence.

Composite Physical Properties: Tensile(2)

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Composite Physical Properties: Impact (1)

) 0.4 0.5 0.6 PP PP + 4 wt.% Cloisite 15A (compatibilized)

Time (ms) 0.0 0.5 1.0 1.5 2.0 Loa d (k N ) 0.0 0.1 0.2 0.3

Composite Physical Properties: Impact (2)

tal E nergy 2 3 4 Cast Sheets

E totalfor neat PP (1 mm thick sheet) ≈ 2 J

Neat PP PPNC1-2 PPNC1-4 PPNC2-2 PPNC2-4 Re la ti v e T o t 0 1 2

Composite Physical Properties: Abrasion

• ASTM D 1044-08 and D1242-87 • 1000 cycles with a 500g weight • 1 Hz

• PA showed better abrasion resistance than PP.

• As % of clay increased, the

abrasion resistance dropped.

Composite Flammability

• Radiant heats of 25 kW/m2and 35 kW/m2

• PA had the best results at low radiant heats.

• At high radiant heats, PA was as good as or better than the PP.

Conclusions – Nanoclay Composites

• Nanocomposites using natural and synthetic clays

in polypropylene and polyamide-6 matrices were

synthesized.

– Polyamide dispersed the clays best.

• Ideally polyamide nanoclay composites are

d b i

l i

h

l

made by intercalating the caprolactam

monomer into the clay and polymerizing in

situ

.

• The physical properties of the nanocomposites

showed minor improvements over the parent

polymers.

– Dispersion played a role.

Conclusions – Military Applications

• What do these results mean for potential textiles?

– Processing plays an important role in realizing

the improved properties of nanoclay

composites.

– Polyamides (a.k.a., nylon) appear to be the

b

i f

l

i

better matrix for nanoclay composites.

– More basic research is needed before these

composites can be transitioned to viable

technology for military applications.

– Nanoclay composites TRL = 2-3

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Future Work

• Move forward with polyamide

– Investigate in situ polymerization

• Durability testing (UV, humidity, temperature)

• CB resistance

• Microfibre and nanofibre formation/testing

– Textile testing, comparison with “bulk”

nanocomposite properties.

Natural clay (Cloisite 15A)

Capillary Rheology for PP-based Nanocomposites

at 200°C

y (P a .s ) 500 (P a .s ) 500 Synthetic clay (Perkalite F100)

Shear Rate (s-1) 100 1000 10000 Sh ear Vi sc osi ty 10 100 PP PPNC2-2 PPNC2-4 Shear Rate (s-1₎ 100 1000 10000 S hear Vi s c os it y 10 100 PP A2 A4

Transient Rheology for PA-based

Nanocomposites

1 0 1.2 1.4 s it y Stress growth test at 240oC

Strain,  0.01 0.1 1 10 100 0.4 0.6 0.8 1.0 Neat PA PA + 2 wt.% Cloisite 15A Commercial PA (1015C2) Relative visco s