Cimtec itri pvc eva tin-ldh nanocomposites interflam 2010

New PVC and EVA nanocomposites based on LDH’s and novel hybrid tin-LDH

nanoparticles

2

Why nanotechnology?Why nanotechnology?

Different nanoparticles, different effectsDifferent nanoparticles, different effects

Spherical particles

Lamellar structure

Tubularstructure

Silica, alumina, ceria, zinc oxide, …

MontmorilloniteHydrotalcite

Flame retardantStabilizer

Carbon nanotubes and nanofibers

Scratch and abrasion resistance, UV filtering

Electrical conductivity

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Nanoparticles and flame Nanoparticles and flame retardancyretardancyMONTMORILLONITE

HYDROTALCITE

Cationic clay: negative charges of layers balanced by the presence of cations in the interlamellar gallery

Anionic clay: positive charges of layers balanced by the presence of anions in the interlamellar gallery

Mg(OH)64-Al(OH)63-

H2O

CO32-

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Nanoparticles and flame Nanoparticles and flame retardancyretardancy

Why nanofiller as flame retardant?Why nanofiller as flame retardant?

• Higher specific surface area

• Lower quantity needed with respect to traditional particles

• Possibility of surface modification to promote the affinity with different polymers

• Improvement of mechanical properties

• Barrier effect of lamellas on oxygen diffusion

5

CimtecLabCimtecLab

R&D Laboratory in AREA Science Park (Trieste)

R&D Laboratory in Soleto (Lecce)

Two R&D laboratories Two R&D laboratories

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CimtecLabCimtecLab

Main R&D activities Main R&D activities

design and development of high-performance

thermosetting and thermoplastic nanocomposites (low

gases permeability, resistance to cryogenic conditions,

halogen-free fire retardant materials, etc.)

development of novel polymeric materials from by-products

of natural origin

study of surface treatments combining sol-gel formulations

and plasma treatments

synthesis of nanoparticles with various techniques (sol-gel,

ionic exchange, etc.)

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Synthesis and modification Synthesis and modification of LDHof LDH

Know-how and expertize of CimtecLab

Co-precipitation route preferred

Other routes under development

Synthesis routes Synthesis routes

Organic modification of Organic modification of

LDH LDH Needed to increase the compatibility between the nanofiller and the polymer

Ion exchange reactions used

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25 30

2Theta

Intensity

d=7.54A

d=3.82A

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15 20 25 30

2Theta

Intensity

d=26,32A

d=13,98Ad=9,58A

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LDH nanocompositesLDH nanocomposites

OM-LDH nanocomposites: high degree of intercalation/exfoliation

Morphological analysis: TEM Morphological analysis: TEM

500 nm 100 nm44.000x 110.000x

Intercalated tactoids +

exfoliated lamellas

Experimental results Experimental results

Intercalated/exfoliated LDH nanocomposites obtained thanks to suitable

organic

modification

Synergy between LDH and phosphorous-based additives

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ITRIITRI

• R & D organisation based in St Albans, UK

• Primarily funded by world’s major

tin producers

• Over 75 year history in tin research – tin metal, its alloys & chemicals

• Specific expertise in inorganic flame retardants & smoke suppressants

• ITRI’s Fireproof Laboratory offers wide range of fire tests, polymer processing & chemical / analytical services to industry

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Current research Current research interestsinterests

Coated fillers & nano-particulate additives

Low smoke - zero halogen formulations

Nanoclays (cationic & anionic) & nano-composites

Natural fibres – flame retardancy, thermal stability, bonding in composites…

Fireproof - small scale polymer compounding & testing

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Zinc stannateZinc stannate

Zinc Hydroxystannate (ZHS)Zinc Hydroxystannate (ZHS)

ZnSn(OH)6 ca. 40% tin by weight

Suitable for use in polymer processing at temperatures below

200°C

Zinc Stannate (ZS) Zinc Stannate (ZS)

ZnSnO3 ca. 50% tin by weight

Suitable for use in all polymer systems

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Technical benefitsTechnical benefits

Very low toxicity – safe & easy to handle

Combined flame retardancy & smoke suppression

Action in condensed & vapour phases

Lower heat release rates

Non - pigmenting & low opacity

Synergy with other flame retardants (halogenated FR’s, inorganic fillers,

nanoclays)

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Coated fillersCoated fillers ITRI developed processes for coating ZHS and ZS on to low cost inorganic fillers

US patent 6,150,447European Patent 833,862

Use of coated fillers allows significant reduction in overall filler loading Better polymer processing Improved physical & mechanical properties

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Coated fillers - typesCoated fillers - typesCoatings Fillers

Zinc hydroxystannate (ZHS) Alumina trihydrate (ATH)

Zinc stannate (ZS) Magnesium hydroxide (MH)

Tin(IV) oxide Calcium carbonate

Tin(IV) phosphate ‘Ultracarb’

Tin(IV) borate Titanium dioxide

Typical coating levels from 2.5 – 10% w/w on filler

SilicaAnhydrous aluminaZinc borateSodium bentoniteNanoclays

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The HYBRID projectThe HYBRID project

Why this project?Why this project?

Main object: to deliver a series of novel fire – retardant additives, each

individual product tailored to meet specific end application requirements

Three different ways to obtain the nanoparticles:

Intercalation of tin organic species between LDH lamellas

Deposition of tin species on to the LDH particles

Partial replacement of Mg/Al ions with Sn ions in the LDH lattice

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Characteristics of novel additives:

inorganic tin – layered double hydroxide synergistic systems

flame retardant and smoke suppressant

non toxic

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Second object: to enhance the fire – retardant functionality of cardanol, a

natural derived by-product of the food industry, and create a new plasticizer

to replace phthalate plasticizers

Cardanol is an oily alkyl –phenolic product (having up to 3 unsaturations in

the flanking alkyl chain) obtained by vacuum distillation of “cashew nut shell

liquid” (CNSL)OH

R

Cardanol

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Increase of environmental concerns

Increase of regulatory activity in relation to certain types of FR

No toxicity (for example, replacement of heavy metal oxides)

Need of halogen – free additives

Need of replacing phthalate plasticizers

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Project tasksProject tasks

1. Synthesis and characterization of LDH including modification with ionic

tin species

2. Synthesis of synergistic tin – LDH FR additive powders including use of

nano-coating techniques

3. Development of novel plasticizer and additive dispersion

4. Compounding and characterization of polymeric nano-composites

5. Laboratory – scale fire test

6. Production and evaluation by industry tests of prototype cables

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Experimental ResultsExperimental Results

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LDH synthesisLDH synthesis2 different methods

NaOH/Na2CO3 METHOD:

• Precipitation of metal salts in a medium of

NaOH/Na2CO3

UREA METHOD:

• Urea is the precipitation medium for

metal

salts

• During urea hydrolysis formation of

carbonate

and hydroxide ions Incorporation of Sn4++ ions

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LDH synthesisLDH synthesis

TestTest

ICP analysis

Scanning electron microscopy

XRD analysis

BET surface area

Malvern particle sizing (wet and dry)

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LDH synthesis – Urea LDH synthesis – Urea methodmethod

Experiment number

Mg/Al/Sn atomic ratio determined from Icp analysis

Mg/(Al+Sn) atomic ratio

Particle size- dry (d0.5, m)

Particle size- wet (d0.5, m)

BET surface area (m2/g)

UREA1 1.1:1:0 1.10 5.0 6.39 31.3

UREA2 1:1:0.12 1.12 3.7 17.7 84.1

UREA3 0.24:1.0:0.46

0.16 86.6 21.64 230.8

UREA4 1.0:1.0:1.0 0.5 144.2 16.5 208.9

UREA5 1.0:1.0:0 1 271.0 - 69.0

UREA6 0.34:1.0:1.0 0.17 200.0 - 221.0

Tin precipitate

0:0:1 0 - - 205.3

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LDH synthesis – Urea LDH synthesis – Urea methodmethodXRD analysisXRD analysis

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Hexagonal platelet structure of the hydrotalcite, which corresponds to the particle size results obtained on the Malvern of 5 microns

SEM: UREA1SEM: UREA1

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27


Hexagonal platelet can be seen, corresponding to the measured particle size of 3.7 microns.

However there is some agglomeration and particles do not seem as ordered as in UREA1


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29


No platelet could be seen on the SEM, probably because the MG:Al stoichiometric ratio for this experiment is 0.24:1.

There are no characteristic hydrotalcite peaks shown on the XRD spectra


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31


No platelet can be seen on the SEM.

Only agglomerated particles of tin oxide.

The XRD spectrum indicates that LDH’s are present.


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Recorded on the precipitate formed when the metal salts were pre-mixed prior to addition of the urea

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LDH synthesis – Urea LDH synthesis – Urea methodmethodICP analysisICP analysis

The Mg:Al atomic ratio is around 1:1 in the final product

In the cases of UREA 3 and 6, the ratio Mg:Al is 0.24:1.0 and 0.34:1.0; LDH lattice was not formed. This result is supported by XRD spectra which show no characteristic peaks of LDH

BET surface area determinationsBET surface area determinationsBET surface area highest when Mg/Al+Sn is low

BET surface area highest when tin content is high

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LDH synthesis – LDH synthesis – NaOH/NaNaOH/Na22COCO33 method method

Experiment number

Mg/Al/Sn atomic ratio determined from Icp analysis

Mg/(Al+Sn) atomic ratio

Particle size- dry (d0.5, m)

Particle size- wet (d0.5, m)

BET surface area (m2/g)

NA1 3.0:0.98:0.0 3.06 88.0 20.86 85.1

NA2 3.0:0.85:0.13

3.02 113.1 27.86 90.9

NA3 3.0:0.79:0.19

3.06 42.3 29.8 15.1

NA4 3.0:0.68:0.39

2.80 64.0 32.7 8.05

NA5 3.0:0.48:0.49

3.09 244.0 19.8 6.1

NA6 3.0:0.0:0.98 3.07 190.7 46.4 29.4

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XRD analysisXRD analysis


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SEM: NA1SEM: NA1


No platelet could be seen on the SEM.

XRD shows the characteristic spectrum of LDH

Platelet are too small to be seen under the SEM

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SEM: NA2SEM: NA2


No platelet can be seen on the SEM, only agglomerated particles

XRD suggest that platelets are present

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40

SEM: NA3SEM: NA3


Agglomerated particles are visible

Hydrotalcite and magnesium hydroxy stannate phases should be both present according to the XRD spectrum

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42

SEM: NA4SEM: NA4




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44

SEM: NA5SEM: NA5




The level of LDH is very low

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46

SEM: NA6SEM: NA6


Agglomerated of magnesium hydroxy stannate

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ConclusionsConclusions

• Urea method is an effective method to produce well ordered hexagonal

hydrotalcite,

but is not compatible with incorporation of Sn into the system

• The ratio Mg/Al is not controllable using urea

• With NaOH/Na2CO3 method the concentrations are much greater than those

used in the

Urea method, the XRD spectra are similar but the size is smaller than 5 microns

• The “optimum” experiment which forms the highest yield of LDH with the

highest

amountof Sn is NA3. It is interesting to evaluate if Sn can be maximised

The next phase of the project is to determine the fire retardant benefits of LDH

with incorporated tin compared with those of a standard LDH

Thank you for your attentionThank you for your attention

Date post:	13-Nov-2014
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Cimtec itri pvc eva tin-ldh nanocomposites interflam 2010

Technology