Synthetic Clays

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la

première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.

https://nrc-publications.canada.ca/eng/copyright

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=ad96aca7-7ebe-4e73-bbdd-ca19c33e9732 https://publications-cnrc.canada.ca/fra/voir/objet/?id=ad96aca7-7ebe-4e73-bbdd-ca19c33e9732

NRC Publications Archive

Archives des publications du CNRC

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Synthetic Clays

L. A. Utracki

NRCC/IMI, 75 de Mortagne, Boucherville, QC, Canada J4B 6Y4

Outline

Introduction

Synthetic clays

Methods of preparation

Properties of synthetic clays

Commercial synthetic clays

Synthetic clays used in CPNC

Synthetic clays no longer commercially produced

CPNC behavior with synthetic clays

Large aspect ratio: Somasif (& Topy-4C)

Small aspect ratio: Lucentite, Laponite, Optigel Other synthetic clays

Summary

PNC market

The polymer

nanocomposites market

annual growth rate is

about 18.4%/y.

The growth rate for

thermoplastics is 20%, and

that of thermosets 10%.

The thermoplastic matrices constitute ca. 77%.

According to BCC, the global market for CPNC increased

from US$90.8M in 2003, to 195 in 2004, and it is expected

to increase to US$311M by 2008.

Use of CPNC in 2004

GM has used CPNC since 2002. In 2004, the company introduced body side molding in the 2004 Chevrolet Impala. The latest application is the 2005 GM Hummer H2 using a TPO-clay formulation.

PP-based CPNC are used in seat backs of the 2004 Acura TL. They are to be used for interior consoles of a 2006 light trucks.

PolyOne has commercialized CPNC masterbatches with high impact strength and stiffness for consumer disposable applications. Its

formulations combine chemical resistance and stiffness and dramatically reduce cycle time.

Semi-aromatic PA-based CPNC (with PA-mXD6) are used as barrier layers in multi-layer PET bottles and films for food packaging, e.g., in Europe for alcoholic beverage bottles, carbonated soft-drink bottles and thermoformed deli meat and cheese containers.

Nanocomposite concentrates are being evaluated in films not only for

enhancing barrier, but also to control the release and migration of additives such as biocides and dyes.

Akzo Nobel developed PNC for coating, pigmenting, and health care products

BASF uses nanoparticles in scratch resistant paints, filtration, and thermoplastic PNC’s. Bayer offers polyamide (PA) based CPNC for film barrier applications.

Clariant manufactures polypropylene (PP) based nanocomposites for packaging.

Dow Chem. applies nanoparticles in filtration and is actively developing CPNC with

thermoplastic matrices.

Eastman Chem. developed multi-layer PET bottles, containers, and films for food packaging having excellent barrier properties. The central layer is a PARA-based CPNC.

Gitto and Nanocor developed polyolefin (PO) nanocomposites for low flammability

applications.

Honeywell developed CPNC for food packaging (films and bottles).

Mitsubishi uses CPNC for the manufacture of

Nanocor and its partners offer several types of CPNC for diverse applications, e.g., based on polyamides (aliphatic and aromatic), PO, etc., to be extruded,

injection, or blow molded.

Rohm & Haas is actively developing CPNC. RTP offers several CPNC’s for diverse applications, including electrical cables and wires.

Toray Ind. developed advanced CPNC Toyota actively develops polylactic acid based CPNC to replace PP composites in its automobiles. PP-based CPNC are used in seat backs of the 2004 Acura TL, and for interior consoles of 2006 light trucks.

Ube and Unitika produce PA-based CPNC for the transportation and packaging markets.

Wilson Sports introduced long-life tennis balls with internal CPNC coatings to

reduce permeability. The technology is to be used for the manufacture of diverse

Industrial activities

Introduction 1

Montmorillonite (MMT)

Platelets welded together by fault in crystal structure

Variable color

Contaminants (grit & amorphous clay)

Fluoro mica (

FM)

ADVANTAGES Aspect ratio: p  6,000 (depends on p of talc) Stable composition Non-toxicity Absence of color DISADVANTAGES

Limited and uncertain sourcing

Higher cost

Introduction 2

1. Semi-synthetic

, prepared by modification of such

minerals as, e.g., talc or obsidian. The resulting fluoro

hectorite (or fluoro mica, FM) has variable aspect ratio and

reactivity (modified by substituting

F

for

–OH

).

2. Fully synthetic

, prepared from metal oxides as, e.g.,

fluoro hectorite: (Si

O

)

(Mg

Li

(OH)

F

. Two

sub-categories are known:

a. The low temperature, hydrothermal slurry process that requires

refluxing for 10 to 20 h to cause crystallization.

b. The high temperature melt process that requires heating at

1300°C for 3 h and then purification by dissolution in water.

3. Templated synthetic

, based on organic templates (e.g.,

prepared by Carrado

– non commercial).

Methods of preparation 1

Semi-synthetic fluoro mica (FM), e.g., Somasif

MMT chemical formula is: [Al_l.67Mg_0.33(Na_0.33)]Si₄O_l0(OH)₂

Hectorite or fluoro hectorite: [Mg_2.67Li_0.33(Na_0.33)]Si₄O₁₀(OH, F)₂ is

obtained from talc: Mg₃Si₄O₁₀(OH)₂ by partially replacing Mg by Li or

Na, and by substituting F for some (ca. 5-wt%) OH groups.

Powdery mixture of talc with 10 to 35 wt% of (Li, Na)₂CO₃, (Li, Na)₂SiF₆

or LiF, is heated for 1 h at T = 700 to 900o_C.

The composition for synthetic FM is, e.g.: talc/LiF/Na₂SiF₆ = 80:10:10,

while for synthetic fluoro-MMT: talc/Na₂SiF₆/Al₂O₃ = 70:20:10.

The heating temperature greatly affects swellability and the interlayer spacing of FM, e.g.:

For T = 700 - 750o_{C, the XRD peak is at d}

001 = 0.91 nm For T = 780 - 900o_{C, the XRD peak is at d}

Methods of preparation 2

Fully-synthetic fluoro mica (FM), e.g., Laponite,

Sumecton-SA, Optigel SH

The hydrothermal process involves:

Preparing aqueous slurry from: MgCl₂, Na₂SiO₃, Na₂CO₃, & LiF Heat the slurry under reflux for 10-20 h (crystallization)

Washing away the

non-crystalline contaminants Drying at T  450 C

Methods of preparation 3

Several

hydrothermal

procedures have been used, viz.:

Preparing water solutions of the basic salts, and then centrifugation to remove possible solid particles

Heat the slurry under reflux for 1 h under ambient pressure, and then transfer to autoclave for the crystallization of hectorite at 250 C

24 hr cooling to RT

The process makes it possible to control the relative

–OH to –F

concentration, thus the FM reactivity.

The aspect ratio of these synthetic clays is low, p = 25 to 50,

dependent on the crystallization conditions.

Main use: surface coating, antistatic paper treatment, household

cleaners, thickener for cosmetics, creams, toothpastes, low-fat sour

cream, paints, adhesives, greases, etc.

MMT was prepared at 220 C for 48 h, in the presence of HF-acid;

Methods of preparation 4

Fully-synthetic fluoro mica (FM), e.g., Topy-4C

The

high-temperature process

involves

Powdering suitable salts, e.g., by ball-milling for 1 h: 3.7-wt% NaF,

2.3% LiF, 10.8 MgF₂, 20.9% MgO, and 62.3% silicic acid; or SiO₂, MgO, Na₂SiF₆ .

Placing the powder in a crucible made from silicon carbide, and then heating in a combustion flame of fuel oil at 1350 to 1600 C for 2 h.

Steaming the slab on a wire net (40 mesh) for 2 h, and thus breaking it into particles of up to 5 mm diameter.

Dispersing the crystals in water under mild stirring at RT for 2 h.

Contamination by non-crystalline byproducts may be eliminated by repeated dissolutions and centrifugations.

The Na-hectorite particles dispersed in the sol state had thickness of 1-5 nm and diameter of p = 80 to 5,000.

Methods of preparation 5

Templated synthetic clays

Dissolve 0.72 mmol of organic salt in water and add 4.8 mmol

LiF with stirring.

Dissolve 24 mmol MgCl

in water, add NH

OH to crystallize

Mg(OH)

.

Add the crystals to the organic-LiF solution, stir for 15 min

before adding 0.036-mol silica sol.

Stir and reflux for 40

48 h. Solids are isolated by centrifugation,

washed, and air-dried.

The Na-hectorite, had the interlayer spacing, d

= 1.48 nm,

and platelet size of L

= 19.5 nm.

Clays grafted with organics were obtained using, e.g.,

phenyl-triethoxy silane (PTES) in the precursor composition.

Properties 1

Synthetic clays that have been used in polymers

No. _{Company Synthetic Clay Clay type}

1 UNICOOPJAPAN,

http://www.unicoop.co.jp Somasif_{fluoro-mica (FM)} ™ ME100, fluoro-hectorite or intercalated grades are available

Semi-synthetic

2 UNICOOPJAPAN,

http://www.unicoop.co.jp Lucentite_{Sodium Silicate; intercalated SAN and} ™ SWN is Lithium Magnesium SPN grades are available

Fully synthetic; Low-T hydrothermal slurry

3 Topy Co., Ltd., JAPAN

http://www.topy.co.jp/

Tetrasilicic mica (fluoro hectorite, FM)

Intercalated grades available

Fully synthetic; High-T melt

5 Kunimine Industries Co., Ltd., Japan; Matsudo@kunimine.co.jp Sumecton®-SA is sodium-saponite (Al-Mg-Silicate Hydrate) Fully synthetic; T > 250°C; hydrothermal 5 Laporte Industries, Ltd.; http://www.laponite.com/

Laponite RD or B is respectively

Na-Li-Mg-silicate, or Na-Li-Mg-fluorosilicate

Fully synthetic; Low-T hydrothermal slurry

6 Süd Chemie AG; www.sud-chemie.com Optigel SH is a Na-Mg-silicate

(Na-hectorite) similar to Laponite RD

Fully synthetic; Low-T hydrothermal slurry

7 FCC INC NO.79 http://www.nanoclay.net SUPLITE-MP is a Na-Mg-silicate

(Na-hectorite) similar to Optigel SH

Fully synthetic; Low-T hydrothermal slurry

8 Haliburton, idp@baroid.com Barasym SMM-100, FM No longer produced

9 Corning, Inc.; BeallGH@Corning.com Fluoro hectorite, Li1.12[Mg4.88Li1.12]Si8F4 or

fluoro phlogopite KMg3(AlSi3O10)F2

Properties 2

Specifications of synthetic and (for comparison)

mineral clays

The

highlighted clays are at IMI

Company Organoclay Intercalant Wt. loss (%) Aspect ratio d001 (nm) CEC (meq/g)

Synthetic clays

CO-OP Somasif ME-100 none 5000 0.95 1.1- 1.2

Somasif MAE 2M2HT 30-40 5000 3.1

Somasif MTE M3O 25-35 5000 2.4

Somasif MEE M2EtOHC 20-30 5000 2.3

Somasif MPE M2E-PPOH 60-70 5000 5..3

Lucentite SWN none < 10 ~50 1.27 0.65

Lucentite SAN 2M2HT 30-40 ~50 1.79 1.2

Lucentite SPN M2E-PPOH 55-65 ~50 4.37 Lucentite SEN M2EtOHC 30-40 ~50 2.39

Lucentite STN M3O 22-32 ~50 2.44

Topy Ind. Topy-4CTs 3MOD ~27 1000-5000 2.32 0.827

Topy-4CDTs 2M2OD ~32 1000-5000 3.18 0.352

Kunimine Sumecton SA none < 10 50 1.3 0.997 - 0.71

Laport Ind. Laponite RD none ~9.5 25 (mono) 0.48

Laport Ind. Laponite B none < 10 ~25

Süd Chemie Optigel SH none < 10 20 – 50

FCC Inc. Suplite-MP none < 10 ~25

Mineral Clays

SCP Na-MMT none 7 ~290 1.23 1.0

10A 2MBHTA 39 ~290 1.93 1.25

20A 2M2HTA 38 ~290 2.47 0.95

30B MT2EtOH 32 ~290 1.86 0.90

Kunimine Kunipia-F none < 10 320 (80-1120) 1.2 1.15

Kunipia-T 3MOD 32.2 ~320 2.07

Somasif

™ ME-100

UNICOOPJAPAN produces the semi-synthetic fluoro

hectorite, SOMASIF,

in a solid-state reaction

, heating

natural talc with 10 to 35-wt% Na

SiF

, and some LiF

(to control

–OH concentration).

For example, a powdery mixture is heated for about 1 h at

T = 700 to 900

_C

_.

Swellable fluoro hectorite (FM) is obtained starting with:

talc/LiF/Na

SiF

= 80:10:10.

The FM produced at 700 - 750

_{C shows the XRD peak at:}

d

= 0.91 nm (of talc) while that at 780 - 900

_{C shows}

d

= 1.61 nm of swellable fluoro mica.

Synthesis of MMT, or saponite-type synthetic clay requires

addition of Al

O

(e.g., talc/Na

SiF

/Al

O

= 70:20:10), and

higher heating temperature.

UNICOOPJAPAN also produces the fully synthetic hectorite,

Lucentite

,

via a hydrothermal

process.

The fully synthetic hectorite, Na

(Mg

Li

)Si

O

(OH)

,

LUCENTITE

is prepared from:

Aqueous solutions of MgCl₂, Na₂SiO₃, Na₂CO₃, and Li₂CO₃

Combining the solution to form a slurry

Heating the slurry under reflux. This step is critical for crystallization, thus the conditions may vary depending on the desired level of

crystal perfection and the aspect ratio; by increasing the salt

concentration and pressure the reflux T  300o_{C has been used}

Washing away the non-crystalline contaminants Drying at T  450 C

Organophilic Lucentite SPN, SEN, STN is available.

TOPY tetrasilicic mica

TOPY Co., developed the high temperature process for the

production of fully synthetic fluoro hectorite (FM):

NaMg

_2.5

Si

₄

O

₁₀

F

₂

The reaction of SiO

, MgO, Na

SiF

and possibly LiF takes

place in the molten state at T > 1500 C.

Crystallization of FM takes place during slow cooling ( 20 h).

The crystalline product is purified by dissolution and

centrifugation.

The aspect ratio of FM is p = 1,000 to 5,000.

TOPY has intercalated FM

for PP-based CPNC

:

4C-Ts with tri-methyl octadecyl ammonium (3MODA), and

4CD-Ts with di-methyl di-octadecyl ammonium (2M2ODA).

Sumecton

®

_-SA

Kunimine Ind. manufactures fully synthetic sodium-saponite,

Sumecton

_{-SA, a Al-Mg-silicate hydrate :}

[(Si

Al

)(Mg

Al

)O

(OH)

]

_(Na

0.49

Mg

)

The synthesis is hydrothermal, with the reflux temperature

under high pressure of T > 250 C. The product properties are:

Aspect ratio p = 50;

Specific surface area = 750 m

_/g;

CEC = 0.997 meq/g (CEC

= 0.71 meq/g);

Average area per anionic site is 1.25 nm

_{, thus the distance}

between ions (square array) is 1.12 nm

The interlayer spacing, d

= 1.3 nm, increases upon

intercalation to 2.6 nm.

Laponite RD or B

Laponite is a fully synthetic hectorite manufactured by Laporte Ind.

(now Rockwood Additives) in a hydrothermal process, distributed in

Canada by Tempo Canada Inc., Oakville, ON.

Of interest is Laponite RD and Laponite B, a hectorite and fluoro

hectorite, respectively.

The structure is that of hectorite:

The reaction starts with refluxing

for 2 h under ambient P, then

under 4 MPa (T = 250

_{C) and}

slowly cooled, filtered & washed.

The

aspect ratio: p



25

!

Laponites are used as thixotropes, in shear-sensitive, water based

formulations, e.g., toothpastes, creams, glazes, paints, etc.

PNC with PA-6 #1

Properties of PNC prepared with ca. 1.6-wt% of mineral (Ube) and

synthetic (Unitika) clay:

(noteworthy are the relative values)

Mechanical properties of PA-6 and based on it PNC.

Data from [Ube Industries, Ltd., 2002, and Unitika Plastics, 2004].

Property ASTM Units Ube Unitika

PA-6 PNC PA-6 PNC Tensile strength,  D-638 kg/cm2 800 910 810 930 Tensile elongation, b D-638 % 100 75 100 4 Flexural strength, f D-790 kg/cm 2 1100 1390 1080 1580 Flexural modulus, Ef D-790 kg/cm2 28,500 35,900 29,000 45,000

Impact strength, NIRT D-256 kg

cm/cm

6.5 5 4.9 4.5

HTD (18.56 kg/cm2) D-648 oC 75 140 70 172

HTD (4.6 kg/cm2) D-648 oC 180 197 175 193

H2O permeability, PH2O JIS Z208 G/m2 24

h

203 106 -- --

PNC with PA-6 #2

Relative properties of PA-

6 based PNC’s prepared with:

natural (pre-intercalated)

MMT

(

Ube

and

IMI

[TSE+GP+EFM])

&

synthetic (not intercalated)

FM

(

Unitika

and

IMI

[SSE+EFM])

clay.

Property ASTM

PNC/PA PNC/PA PNC/PA PNC/PA

Process In-situ polymerization Melt compounding

Clay used in PNC -- MMT FM MMT FM

Mineral clay wt% -- 1.6 1.6 1.14 1.14

Tensile strength, /matrix D-638 1.14 1.15 1.06 1.00

Tensile elongation, b /b, matrix D-638 0.75 0.04 0.33 0.38

Flexural strength, f /f, matrix D-790 1.26 1.46 1.07 1.13

Flexural modulus, Ef /Ef, matrix D-790 1.26 1.55 1.14 1.20

Impact strength, NIRT/NIRTmatrix D-256 0.77 0.92 0.99 0.76

HTD – HTDmatrix (18.56 kg/cm2) (°C) D-648 65 102 -- --

HTD – HTD (4.6 kg/cm2) (°C) D-648 17 18 -- --

Relative mechanical properties of PA-6 based PNC’s.

PNC with PA-6 #2

Ube process

MMT pre-intercalated with

w-amino dodecanoic acid in

water; d₀₀₁ = 1.8 nm.

Dispersed organoclay in molten

-caprolactam and water at the

ratio: 1:9:9.

Swelling the organoclay to

d₀₀₁ = 3.87 nm.

Polycondensation under N₂ at

250-270°C for 48 h was followed by pelletization.

The -caprolactam was

extracted from the pellets immersed in a hot water, followed by vacuum drying [Deguchi et al., 1992].

Unitika process

20-wt% water, -caprolactam,

and non-intercalated FM.

Several types of FM were prepared and tested.

The mixture was polymerized

under N₂ at 250 C, stirring for

1 h at P = 4 to 15 atm.

The steam was reduced to 2 atm and polymerization continued at 260 C for 3 h. The PNC pellets were washed with water at 95 C for 5 h, then dried at 100 C under vacuum for 8 h [Yasue et al., 1995].

PA-66 with Somasif

TM

Showa Denko prepared a rigid, flame-resistant PNC by compounding:

(1) PA-66, (2) Somasif ME-100 intercalated with either triazine (C₃H₃N₃),

melamine, cyanuric acid, or melamine cyanurate, (3) fibrous reinforcements, and (4) flame retardant

[Inoue et al., US Pat., 6,294,599, 2002].

PNC of PA-66 with 1 phr of clay and 15 phr of GF. Data: [Inoue et al., 2002]. No. Organoclay or other filler d001 (nm) Flex modulus (MPa) HDT (oC) Deformation (mm) Relative shrinkage (TD/MD) 1 FM + m 1.28 6.3 245 0.5 1.94 2 MMT + m 1.30 6.1 244 0.7 1.86 3 FM + mc 1.50 6.2 244 0.7 1.96 4 FM + 2xm 1.35 5.9 240 1.0 2.12 5 FM + 2M2ODA 3.5 5.8 230 1.2 1.88 6 Talc 0.96 6.0 243 1.0 2.13 7 nil -- 5.6 244 6.2 2.30

Notes: FM = synthetic clay, Somasif ME-100; MMT = Kunipia-F; m = melamine; mc = melamine cyanurate; 2M2ODA = di methyl -di-octadecyl ammonium chloride; 2x

PP with Somasif

TM

_#1

Several articles describe preparation of PP-based PNC with FM, using either reactive or melt compounding methods.

FM seems to be easier to disperse than MMT [Kawasumi et al., 1997].

The Young’s modulus (E) linearly increases with d001

[Reichert et al., 2000].

Reactively prepared PE with Somasif followed the highest E_R vs. w

dependence [Heinemann et al., 1999].

Melt compounded PNC with PP + PP-MA as the matrix showed ca. 30%

lower E_R values than the best performing PNC (see next slide).

A plausible explanation is shear attrition of clay platelets during

compounding. Zilg et al. [1999] noted that after high shear mixing of

Somasif with PU, the aspect ration decreased from p = 5000 to 132. The anisotropic particles resembled short fibers.

PP with Somasif

TM

_#2

Relative Young’s modulus vs. inorganic clay content for PP PNC:

1 2 3 0 4 8 E RPA E RPP E RPLA E R PP (fluoro mica) E RPS R e lat iv e m o d u lus , E R ( -) Clay content, w (wt%) E R = 1 + 0.2w E R = 1 + 0.07w E R = 1 + 0.13w Hard sphere

The lhs Figure show the relative (to matrix) values of Young’s modulus vs. inorganic clay content for several types of PNC.

The rhs Figure presents the data for Somasif, intercalated with protonated

n-paraffin amines (C12 to C18) with PP and PP + 20-wt% Epolene 43 (E: M_w = 23,

1 1.5 2 2.5 3 0 2 4 6 8

Relative Young's modulus vs. Somasif content for the melt compounded PP-based PNC

Reichert et al., 2000 C12; PP C16; PP C18; PP C12; PP+20E C16; PP+20E C18; PP+20E C12; PP+20H C16; PP+20H C18; PP+20H the best PNC E R = E c /E m Somasif content, w(wt%) E R = 1 + 0.2w

PP with Somasif

TM

_#3

Leuteritz et al. (Macromol.

Symp.,

2005, 221, 53-61)

examined the effect of clay on

performance of PP-based

CPNC.

3 mineral MMT’s and Somasif

ME100 were pre-intercalated

with

2M2ODA

:

CPNC contained 5-wt% clay, 7.5

As the Figure above

illustrates, the best

performance was obtained

for the synthetic clay

(Y = 2.14 GPa, i.e., 61% higher, while the impact strength 32%

PLA with Somasif

TM

Unitika

commercialized poly lactic acid (PLA)

nanocomposites with synthetic clay under name

of

TERRAMAC

.

13 grades are available for extrusion, injection

molding, blow molding, foaming, etc.

Test method ISO Unit PLA CPNC

Appearance - - Transparent Opaque

Density 1183 - 1.25 1.47 Melting point - °C 170 170 Strength 527 MPa 63 54 Elongation 527 % 4 1 Modulus 178 GPa 4.3 9.5 NIRT 179 kJ/m2 _{1.6 2.4} HDT 75 °C 58 140

Zilg et al. [1999] prepared PNC with anhydride-cured epoxy matrix.

Three clays were :

Somasif (FM), Na-MMT, and Optigel SH (H).

The clays were intercalated with 2MBODA (B);

d₀₀₁ = 1.7 to 1.8 nm for all.

Optigel showed the worst performance.

At  5-wt% loading FM was the best.

At loadings  5-wt% FM was more difficult to disperse than MMT, while H exfoliated quite readily. This effect correlates with the aspect ratios, viz. p  5000, 300, and 25.

1 0 3 0 5 0 7 0 9 0 15 0 25 0 35 0 45 0 55 0 0 2 4 6 8 1 0 M MT M M T/B FM/B H H/B E lo n g a ti o n a t b re a k ,  (% ) F_ra c tu re e n e rg y , G 1c (J /m 2 ) C lay content, w (w t% )  G 1 c G 1 c 

Xu et al.,

prepared CPNC by

heterocoagulation of cationic PMMA emulsion and

aqueous dispersion of clay (

with or without Na

P

O

).

PMMA with Somasif

TM

CPNC were exfoliated at the clay loading < 5-wt%.

DTG indicated best stabilization by MMT, and the worst (no effect) by Somasif.

The improvement of the thermal stability was assigned to the presence of Fe, or Al, but not the clay aspect ratio.

PNC with Lucentite

Kuwabara et al. [1998] used Lucentite SPN

swollen with tri-ethyl phosphate (TEP) to

thicken polyol stock for rigid PU foams.

The thixotropic effect was proportional to clay

concentration.

Well mixed stock solution, containing from 0.7

to 1.5-wt% of SPN and up to 20-wt% Sb

O

was

allowed to stand for 15 days at RT.

There was no sedimentation of Sb

O

.

The resulting hard PU foam showed stable low

density and good flame retardancy.

PNC with Laponite

McCarthy et al. [1996] used suspension of Laponite (LP) in epoxy to form a flexible, antistatic film on polymeric substrate was described.

Doeff et al. [1998] intercalated PEG into Laponite, for enhanced Li+ _ion

conductivity in rechargeable batteries.

Inan et al. [2003] polymerized PA-6 in the presence of 5-wt% LP and/or MMT. The best char formation and flame-retardation was obtained for LP/MMT (-53% PHRR), than for MMT (-51%) and PL (-45%).

Shemper et al. [2004] reported auto acceleration of polymerization caused by Laponite RD, resulting in high conversion. The system was:

methyl a-hydroxy-methyl-acrylate (MHMA) with hydroxylated dimethyl

acrylate crosslinker. XRD and TEM indicated exfoliation.

Loyens et al. (Polymer, 2005, 46, 915-28) modified Laponite RD with

glycols, compounded masterbatch of PEG with 10-wt% clay, and then diluted to CPNC with 0 to 5-wt% clay. The intercalated systems showed only a slightly better mechanical performance, explained by low aspect ratio (p = 25).

PNC with Optigel

Zilg et al. [1999] used Optigel SH for the preparation of PNC with

anhydride-cured epoxy. At 5-wt% clay loading Optigel with the smallest aspect ratio was readily exfoliated. However, the presence of Optigel induced modest improvement of properties.

Osman et al. [2004] prepared a series of

HDPE-based PNC’s by melt-compounding.

Natural, based on MMT, clays were used, viz. Nanofil, Cloisite, Optigel C-series. At constant volume of the clay the

mechanical performance correlated with

the interlayer spacing, d₀₀₁.

Note that the properties are not sensitive to the clay aspect ratio, p = 59 to 300, but only to d₀₀₁.

There are three types of synthetic clays :

1.Semi-synthetic, based on natural talc (e.g., Somasif). Advantages:

high aspect ratio, p  6000 (problems: exfoliation, attrition) lack of color variability

2.Fully synthetic, from variety of metal salts or oxides. Advantages:

stability of their composition, color, and size, thus non-toxicity mainly circular disks with p = 10 to 50; TOPY p = 1000 to 5000 absence of inherent color and color variability

3.Templated synthetic, based on organic templates, which after

synthesis may act as intercalants (not commercial).

Only Somasif is used in commercial production of PNC; TOPY has a good potential.

The fully synthetic clays with low aspect ratio are used as thixotropes in aqueous systems (the food, cosmetics, pharmaceuticals, and paint industries). Their effect in CPNC is small.

The available semi-synthetic fluoro mica (FM) from COOP and fully synthetic FM from TOPY are:

1. Somasif ME-100 & Somasif MAE [intercalated with 2M2T (or 2M2HT)]

2. TOPY 4C-Ts [intercalated with 3MOD], & TOPY 4CD-Ts [with 2M2OD]

The COOP FM should be used in well established PNC formulations where SCP organoclays have been employed.

The high aspect ratio, fully synthetic FM from TOPY was designed for PP, and it should be used in corresponding formulations of PNC.

Considering the high aspect ratios of these fluoro micas, mild processing conditions and long residence time are desired; hence the use SSE + EFM-N is recommended.

The low aspect ratio, fully synthetic clays:

1. Lucentite SWN and SAN [with 2M2T (or 2M2HT)] from COOP

2. Sumecton-SA from Kunimine Ind.

may be used in polymeric systems as such, e.g, to control abrasion.

 Performance of MMT-based Kunipia-F, -T, and –D should be compared with