12Real and Potential Applications

As summarized in a number of chapters, PNCs generally exhibit mechanical properties

superior to those of conventional polymer composites. More important, however, PNCs

introduce new properties to the polymer matrices, such as decreased gas and water vapor

permeation, higher heat distortion temperatures, and improved scratch resistance. In

addition to their improved mechanical and materials properties, PNCs are also easily

molded into their final shape, which simplifies the manufacturing process of PNC-based

products [1]. The properties of PNCs have been shown to be attained at much lower clay

contents than conventionally filled composite systems. For these reasons, PNC-based

products are significantly lighter than the products manufactured from conventional

composites. Such a weight advantage could significantly influence environmental con-

cerns. For example, a recent study showed that widespread use of PNCs by U.S. car man-

ufacturers could save 1.5 billion liters of gasoline over 1 year of vehicle production and

reduce related CO2 emissions by more than 10 billion pounds [1]. Furthermore, the

improved barrier properties, in combination with the balanced mechanical properties

of PNCs, could eliminate the need for multiple-layer food packaging materials and

thereby enable greater recycling of food and beverage packaging. This increased recycling

alsowould significantly affect the environment. Another unique opportunity in the case of

PNC technology is the design of materials with only the desired properties by fine-tuning

the interfacial chemistry between the clay surface and polymer matrix.

Recently, a common question has arisen as towhy, with all of the interesting properties

of PNCs, the opportunity to fine-tune their properties and huge worldwide efforts asso-

ciated with a significant R&D expenditures in PNC technology, have significant commer-

cial impacts not occurred. Major discoveries take several decades to achieve a significant

commercial impact; some examples include polyethylene and carbon-fiber composites.

At the early stages of discovery, the processibility, properties, and performance/cost vari-

ables are outside the realm of commodity utility; and additional major advances are

required to achieve an economically competitive position [2]. The commodities of today

were the specialties of the past. One example is the automobile, which was a specialized

article of commerce for several decades. The technologies being developed with PNCs are

similarly positioned: although many of the applications being commercialized today will

remain specialties, other areas exist where the specialty PNCs of today will be the com-

modities of the future.

In the 1990s, Toyota Motors Corporation first introduced N6–clay nanocomposites in

timing-belt covers. Such timing-belt covers exhibited good rigidity, excellent thermal sta-

bility, and no warp. Moreover, the use of the nanocomposites reduced the weight of the

component 25%. Because of the dramatic improvement in mechanical and thermome-

chanical properties, combined with barrier properties, the automobile industry is now

Clay-Containing Polymer Nanocomposites: From Fundamentals to Real Applications

© 2013 Elsevier B.V. All rights reserved.369

370 CLAY-CONTAINING POLYMER NANOCOMPOSITES

using N6–clay nanocomposites for themanufacture of the engine cover, oil reservoir tank,

and fuel hoses. In 2002, General Motors introduced thermoplastic polyolefin–clay nano-

composites for the manufacture of step-assists on their GMC Safari and Chevrolet line of

vehicles. In recent years, various companies have manufactured potential interior and

exterior car parts, such as door handles, under-the-hood parts, andmirror housings, using

nanocomposites. At approximately the same time, Bayer and GE developed PC–clay

nanocomposite-based auto-glazing for exterior coatings that require weatherability and

abrasion resistance without reduced clarity [2].

Similarly, the excellent oxygen-barrier and water-vapor-barrier properties, combined

with the balancedmechanical properties of PNCs, would result in a considerable enhance-

ment of the shelf life formany types of packaged foods.Moreover, the optical transparency

of highly delaminated PNC films is generally similar to that of the neat polymer. Therefore,

all these advantageous propertiesmake PNCs widely acceptable in the packaging industry

as wrapping films and beverage containers for products such as processedmeats, cheeses,

confections, cereals, fruit juices, dairy products, beer, and carbonated drinks. In this

regard, biodegradable polymer-based nanocomposites show huge potential. PNCs have

also shown improved flame-retardant properties, which would open up applications in

a variety of other areas, such as building materials, computer housings, and car interiors.

Other potential applications include controlled drug delivery systems and nanopig-

ments that are believed to be an environmentally friendly alternative to toxic cadmium

and palladium pigments. For example, Cypes et al. found that, in the case of biocompat-

ible poly(ethylene-co-vinyl)/clay nanocomposite systems, the incorporation of organi-

cally modified clays not only reduced the rate of drug release but also increased the

tensilemodulus compared to that of the neat polymer. Similarly, Lee and Fu [3,4] prepared

poly(N-isopropylacrylamide)/clay nanocomposite hydrogels and report that the drug

release depended on a variety of factors, such as the charge of the drug solute, the loading

of the clay and its intercalated agents, the interaction between the gel and the drug solute,

and the ionic strength of the medium. Meanwhile, Ambrogi et al. [5] studied the drug

inclusion and in-vitro release of intercalation compounds and microporous materials

from kanemite. The properties and main applications of some important PNCs are sum-

marized in Table 12.1.

Over the past few years, many companies have taken a strong interest in nanoclays and

PNCs, refer to Table 12.2. Recently, an increasing number of commercial products have

also become available in the market. In this context, Table 12.3 summarizes the main

applications of PNCs along with their commercial status.

In 2010, global consumption of nanocomposites was estimated to be 118,768 metric

tons with a value greater than $800 million. In 2011, the market was estimated to

138,389 metric tons with a value of $920 million; and by 2016, it should be 333,043 metric

tons with a value of $2.4 billion. These estimates therefore predict a gross annual growth

rate of 19.2% in unit terms and 20.9% in value terms between 2011 and 2016.

PNCs accounted for more than 50% of the total consumption by value in 2010, and

their market share is expected to increase approximately 58% by 2016. Automotive parts,

Table 12.1 The Properties and Main Applications of PNCs

Matrix–Clay Main Properties Applications

Nylon 6–MMT Heat resistance

Barrier properties

Tensile strength elasticity

Impact resistance

Automotive parts

Packaging

Medical devices

Flame-retardant materials

Thermoplastic polyolefin–MMT Shock resistance

Heat resistance

Automotive parts

Ethyl vinyl acetate–MMT Flame retardance

Chemical resistance

Thermal stability

Ease of processing

Halogen free

Cable and wire sheeting

Polypropylene–MMT High flexural modulus

High-impact resistance

Low bulk density

Scratch, mark resistance

Fire retardance

Automotive parts

Packaging

Office furniture

Polyethylene–MMT High flexural modulus

High impact resistance

Low bulk density

Scratch, mark resistance

Packaging

Automotive parts

Acetal–MMT High flexural modulus

Heat resistance

Automotive parts

Electronics

Nylon 6–SFM Heat resistance

Barrier properties

Tensile strength elasticity

Impact resistance

Automotive parts

Butyl rubber–vermiculate Air barrier Sporting goods

Poly(vinyl chloride)–bentonite Plasticity, viscosity, and flow Automotive parts

Artificial leather

Source: BCC Research, Wellesley, MA.

Table 12.2 Clay-Containing Polymer Nanocomposites Suppliers

Supplier Product Name Matrix Resin Main Application(s)

Alcoz CSI Nylon 6 Packaging

Bayer AG Durethan Nylon 6 Packaging

Clariant Polypropylene Packaging

DuPont Thermoplastic polyolefin Automotive

Electrical

Electronic

Foster Corp. Nanomed Nylon 12 Medical devices

Honeywell Aegis Nylon 6 Automotive painted parts

InMat Air D-Fense

Nanolok

Butyl rubber

Polyethylene

Sporting goods

Packaging

Continued

Chapter 12 • Real and Potential Applications 371

Table 12.3 Main Applications of PNCs with Their Commercial Status

Applications PNC Types Commercial Status

Automotive Nylon 6–MMT Commercially available

Thermoplastic polyolefins–MMT Commercially available

Polypropylene–MMT Commercially available

Polyethylene–MMT Under development

Acetal–MMT Commercially available

Butyl rubber–vermiculate Under development

Nylon 6–SFM Commercially available

Packaging Nylon 6–MMT Commercially available

Polyethylene–MMT Commercially available

Polypropylene/MMT Under development

Poly(ethylene terephthalate)–MMT Under development

Ethyl vinyl alcohol–MMT Under development

Life sciences Nylon 6–MMT Commercially available

Consumer products Butyl rubber–vermiculate Butyl rubber/vermiculate

Polypropylene–MMT Under development

Flame-retardant materials Ethyl vinyl acetate–MMT Butyl rubber/vermiculate

Polypropylene–MMT Under development

Source: BCC Research, Wellesley, MA.

Table 12.2 Clay-Containing Polymer Nanocomposites Suppliers—cont’d

Supplier Product Name Matrix Resin Main Application(s)

Neoprene

Chloroprene

Nitrile rubber

Tires

Chemical protective

gloves

Kabelwerk Eupen Ethyl vinyl acetate Wire and cable

LG Chemicals High density polyethylene Packaging

Mitsubishi Chemicals Imperm Nylon 6 Packaging

Noble Polymers Forte Polypropylene Automotive parts

Appliances

Office furniture

Polymeric Supply Unsaturated polyester Marine transportation

PolyOne Nanoblend

Maxxam LST

Polypropylene

Polyethylene

Automotive

Packaging

Flame retardance

RTP Ecobesta Nylon 6

Acetal

Auto fuel systems

Packaging

Multipurpose

Unitika Nylon M1030DH Nylon 6 Multipurpose

Yanti Haili Industry

and Commerce

UHMPWE Earthquake-resistant pipe

372 CLAY-CONTAINING POLYMER NANOCOMPOSITES

Chapter 12 • Real and Potential Applications 373

packaging, and coatings were themain applications of PNCs on aworldwide basis in 2012,

with 41%, 32%, and 16% of the market. In the coming years, packaging applications are

expected to increase to 46%, and significant expected applications of textiles are expected

by 2016.

References[1] Vaia RA, Giannelis EP. Polymer nanocomposites: status and opportunities. Mater Res Soc Bull

2001;26:394–401.

[2] Zeng QH, Yu AB, Lu GQ, Paul DR. Clay-based polymer nanocomposites: research and commercialdevelopment. J Nanosci Nanotechnol 2005;5:1574–92.

[3] Lee WF, Fu YT. Effect of montmorillonite on the swelling behavior and drug-release behavior of nano-composite hydrogels. J Appl Polym Sci 2003;89:3652–60.

[4] Lee WF, Fu YT. Effect of the intercalation agent content of montmorillonite on the swelling behaviorand drug release behavior of nanocomposite hydrogels. J Appl Polym Sci 2004;94:74–82.

[5] Ambrogi V, Chiappini I, Fardella G, Grandolini G, Marmottini F. Microporous material from kanemitefor drug inclusion and release. Farmaco 2001;54:421–5.