This document summarizes experimental results from synthesizing and characterizing layered double hydroxide (LDH) nanoparticles and tin-LDH hybrid nanoparticles using different methods. Two LDH synthesis methods were tested: the urea method and NaOH/Na2CO3 method. Characterization using ICP, XRD, SEM and BET surface area analysis showed that the urea method produced well-ordered hexagonal LDH platelets but did not successfully incorporate tin. The NaOH/Na2CO3 method resulted in LDHs and magnesium hydroxy stannate phases with increasing tin content, but platelets were not visible by SEM. The optimal synthesis depends on the desired Mg/Al/Sn ratio and applications require further development

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

2. 2
Why nanotechnology?Why nanotechnology?
Different nanoparticles, different effectsDifferent nanoparticles, different effects
Spherical
particles
Lamellar
structure
Tubular
structure
Silica, alumina,
ceria, zinc oxide, …
Montmorillonite
Hydrotalcite
Flame retardant
Stabilizer
Carbon nanotubes
and nanofibers
Scratch and
abrasion
resistance, UV
filtering
Electrical
conductivity

3. 3
Nanoparticles and flameNanoparticles and flame
retardancyretardancy
MONTMORILLONITE 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)6
4-
Al(OH)6
3-
H2O
CO3
2-

4. 4
Nanoparticles and flameNanoparticles 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. 5
CimtecLabCimtecLab
 R&D Laboratory in AREA Science Park (Trieste)
 R&D Laboratory in Soleto (Lecce)
Two R&D laboratoriesTwo R&D laboratories

6. 6
CimtecLabCimtecLab
Main R&D activitiesMain 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.)

7. 7
Synthesis and modification of LDHSynthesis and modification of LDH
 Know-how and expertize of CimtecLab
 Co-precipitation route preferred
 Other routes under development
Synthesis routesSynthesis routes
Organic modification of LDHOrganic modification of 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=13,98A
d=9,58A

8. 8
LDH nanocompositesLDH nanocomposites
OM-LDH nanocomposites: high degree of intercalation/exfoliation
Morphological analysis: TEMMorphological analysis: TEM
500 nm 100 nm44.000x 110.000x
Intercalated tactoids +
exfoliated lamellas
Experimental resultsExperimental results
 Intercalated/exfoliated LDH nanocomposites obtained thanks to suitable organic
modification
 Synergy between LDH and phosphorous-based additives

9. 9
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

10. 10
Current research interestsCurrent research interests
 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

11. 11
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

12. 12
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)

13. 13
Coated fillersCoated fillers
 ITRI developed processes for coating ZHS and ZS on to low cost inorganic
fillers
US patent 6,150,447
European Patent 833,862
 Use of coated fillers allows significant reduction in overall filler loading
 Better polymer processing
 Improved physical & mechanical properties

14. 14
Coated fillers - typesCoated fillers - types
Coatings 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
Silica
Anhydrous alumina
Zinc borate
Sodium bentonite
Nanoclays

15. 15
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

16. 16
The HYBRID projectThe HYBRID project
Why this project?Why this project?
Characteristics of novel additives:
 inorganic tin – layered double hydroxide synergistic systems
 flame retardant and smoke suppressant
 non toxic

17. 17
The HYBRID projectThe HYBRID project
Why this project?Why this project?
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

18. 18
The HYBRID projectThe HYBRID project
Why this project?Why this project?
 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

19. 19
The HYBRID projectThe HYBRID project
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

20. 20
Experimental ResultsExperimental Results

21. 21
LDH synthesisLDH synthesis
2 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

22. 22
LDH synthesisLDH synthesis
TestTest
 ICP analysis
 Scanning electron microscopy
 XRD analysis
 BET surface area
 Malvern particle sizing (wet and dry)

23. 23
LDH synthesis – Urea methodLDH synthesis – Urea method
Experiment
number
Mg/Al/Sn
atomic ratio
determined
from Icp
analysis
Mg/(Al+Sn)
atomic
ratio
Particle size-
dry (d0.5,
µm)
Particle size-
wet (d0.5,
µm)
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

24. 24
LDH synthesis – Urea methodLDH synthesis – Urea method
XRD analysisXRD analysis

25. 25
LDH synthesis – Urea methodLDH synthesis – Urea method
Hexagonal platelet structure of
the hydrotalcite, which
corresponds to the particle size
results obtained on the Malvern
of 5 microns
SEM: UREA1SEM: UREA1

26. 26
LDH synthesis – Urea methodLDH synthesis – Urea method
XRD analysisXRD analysis

27. 27
LDH synthesis – Urea methodLDH synthesis – Urea method
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
SEM: UREA2SEM: UREA2

28. 28
LDH synthesis – Urea methodLDH synthesis – Urea method
XRD analysisXRD analysis

29. 29
LDH synthesis – Urea methodLDH synthesis – Urea method
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
SEM: UREA3SEM: UREA3

30. 30
LDH synthesis – Urea methodLDH synthesis – Urea method
XRD analysisXRD analysis

31. 31
LDH synthesis – Urea methodLDH synthesis – Urea method
No platelet can be seen on the
SEM.
Only agglomerated particles of
tin oxide.
The XRD spectrum indicates that
LDH’s are present.
SEM: UREA4SEM: UREA4

32. 32
LDH synthesis – Urea methodLDH synthesis – Urea method
XRD analysisXRD analysis
Recorded on the precipitate formed
when the metal salts were pre-mixed
prior to addition of the urea

33. 33
LDH synthesis – Urea methodLDH synthesis – Urea method
ICP 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 determinations
BET surface area highest when
Mg/Al+Sn is low
BET surface area highest when tin
content is high

34. 34
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
Experiment
number
Mg/Al/Sn
atomic ratio
determined
from Icp
analysis
Mg/(Al+Sn)
atomic
ratio
Particle size-
dry (d0.5,
µm)
Particle size-
wet (d0.5,
µm)
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

35. 35
XRD analysisXRD analysis
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod

36. 36
SEM: NA1SEM: NA1
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
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

37. 37
XRD analysisXRD analysis
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod

38. 38
SEM: NA2SEM: NA2
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
No platelet can be seen on the
SEM, only agglomerated particles
XRD suggest that platelets are
present

39. 39
XRD analysisXRD analysis
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod

40. 40
SEM: NA3SEM: NA3
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
Agglomerated particles are
visible
Hydrotalcite and magnesium
hydroxy stannate phases should
be both present according to the
XRD spectrum

41. 41
XRD analysisXRD analysis
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod

42. 42
SEM: NA4SEM: NA4
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
Agglomerated particles are
visible
Hydrotalcite and magnesium
hydroxy stannate phases should
be both present according to the
XRD spectrum

43. 43
XRD analysisXRD analysis
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod

44. 44
SEM: NA5SEM: NA5
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
Agglomerated particles are
visible
Hydrotalcite and magnesium
hydroxy stannate phases should
be both present according to the
XRD spectrum
The level of LDH is very low

45. 45
XRD analysisXRD analysis
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod

46. 46
SEM: NA6SEM: NA6
LDH synthesis – NaOH/NaLDH synthesis – NaOH/Na22COCO33
methodmethod
Agglomerated of magnesium
hydroxy stannate

47. 47
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

48. Thank you for your attentionThank you for your attention