Nanocomposites
A composite is a combination of two or more different materials mixed in an effort to blend the best properties of both. A nanocomposite is a composite material in which one of the components has at least one dimension that is nanoscopic in size. The ‘nano’ in the name refers to the prefix for meter in the metric system, which refers in turn to an exponent, 1 (´) 10-9 m (1 nm). Some relative sizes might helpful provide a sense of scale: a coin is on the order of 1 - 2 mm thick, or 10-3 m; a grain of sand is about 100 µm in diameter, a human hair runs about 30 µm, and a carbon fiber, commonly used as a reinforcement in sporting goods, is approximately 7 µm in diameter, or 10-6 m; polishing compounds such as alumina, diamond and jeweler’s rouge can be as small as 100 nm; fumed silica and carbon black are about 10 nm; a carbon-carbon chemical bond, the basic unit of life, is about 1.5 Å, or 10-10 m. Viewing the polymer as a mechanical weak link, traditional composites focus on improving the volume fraction of reinforcement or improving interactions between reinforcement and matrix. Whereas traditional composites use over 40% by weight of reinforcement, nanocomposites may show improvements at less than 5%. Twardowski 9/16/2009
The term “nanocomposite” appears to have been coined in 1986. Since then, growth in the field has been geometric (Figure 1.1). According to Google Scholar™, in 1986 there were 2 papers. Twenty years later, in 2006, there were 1,310 new articles with nanocomposite in the title alone, reported in journals ranging from Advanced Materials to Wear. With over 14,000 articles mentioning nanocomposites in some way, articles have appeared in just about every materials journal. The field of nanocomposites is burgeoning. A brief look at new, common commercial uses reveals automotive panels for sports utility vehicles, polypropylene nanocomposites for furniture, appliances, and bulletin board substrates. Advanced technologies implemented include magnetic media, bone cement, filter membranes, aerogels, and solar cells. Nanocomposites represent one area of nanoscale research that has led to marketable products. However, not all of the technologies are new. Fumed silica has long been used as a thickener, while carbon black is a common black pigment. The future of nanocomposites will almost certainly be determined as much by those who can look back as by those looking forward. Materials used for nanocomposites can be low technology: soot, ash, and clay. They can use the most advanced fullerene materials implementing master batches and advanced formulation techniques. Some of the nanoparticles in most common use are silicate clays treated to form nanoscopic flakes. One may deal with nanoparticulates that are particles (1D), fibers (2D), or flakes (3D) where the number of dimensions that are macroscopic define the geometry. An alternative describes particles by the number of dimensions that are nanoscopic. While nanoparticles have been around throughout time, the terminology used as humans begin to deliberately study the materials is still in flux. In literature sources, reinforcement is often used to refer to the ceramic particle regardless of whether the particles are actually serving as reinforcements. Funding agencies have restricted the definition of nanocomposite to include reinforcement sizes of less than 100 nm, although this is not connected to the reinforcing performance of the particles. Press releases often state that the properties of materials at this size scale are different than the bulk behavior of the material. To be more correct, the surface properties of the material begin to take on more significance as the particle size decreases. The presence of a distinct boundary between the binding matrix and reinforcing particles seems to be necessary to reinforcing or other property changes. Twardowski 9/16/2009
Acrylic Nanocomposites
Carbon Nanocomposites
Cellulose Acetate Nanocomposites
Cellulose Nanocomposites
Clay Nanocomposites
Composites
Conductive Nanocomposites
Elastomer /Rubber Nanocomposites
Epoxy Nanocomposites
Injection Molding Nanocomposites
Interpenetrating Networks (IPN)
Laminating
Materials
Nanocomposite Glass Transitions
Nanocomposites by Mixing
Phenolic Nanocomposites
Nanodiamond Nanocomposites
Polyamide Nanocomposites
Polyethylene Nanocomposites
Polynorbornene Nanocomposites
Polyolefin Nanocomposites
Polystyrene (PS) Nanocomposites
Silsesquioxane (POSS)Nanocomposites
Tannin Nanocomposites
Recent Journal Articles
Extrusion of Nanocellulose-Reinforced Nanocomposites Using the Dispersed Nano-Objects Protective Encapsulation (DOPE) Process
(984–991) Macromolecular Materials and Engineering 296 #11 (2011)
Lemahieu et al of The International School of Pape, France, formed cross-linked alginate capsules a few millimeters in diameter have by immersion in a CaCl2 solution. When adding cellulose whiskers or microfibrillated cellulose to the aqueous alginate solution, nanocomposite capsules containing 40 wt.% cellulosic nanoparticles were obtained. The capsules were extruded with a thermoplastic polymer. Visual inspection of the ensuing films shows a nonhomogeneous dispersion of the capsules that kept their integrity after extrusion. (RDC 11/3/2011).
Films of Highly Disperse Electrodeposited Poly(N-vinylcarbazole)–Graphene Oxide Nanocomposites
(2371–2377) Macromolecular Chemistry and Physics 212 #21 (2011)
Santos et al of the University of Houston, Texas, electrodeposited polymer nanocomposite thin films of PVK–GO. Highly exfoliated and stable graphene oxide (GO) solutions are prepared by incorporating poly(N-vinylcarbazole) (PVK) through mixing. The presence of GO on the PVK–GO surface is confirmed by the appearance of the C=O and OH stretching vibrations, attributed to the carboxylic and hydroxyl groups of GO. (RDC 11/3/2011)
Quantitative 3D measurement of the nanostructural features that dictate mesoscale performance properties of nanocomposites
(pages 1495–1503) Polymer Composites 31 #9 (2010)
Mahboob et al Ohio State University developed a method for obtaining the nanofiber orientation in 3D Euclidean space from 2D projections provided by a transmission electron microscope. The 3D Euler angles we obtain are used to construct orientation tensors, the measure of nanostructure that has the most significant influence on mesoscale performance properties. It is shown that orientation tensor data obtained from our experimental method accurately fits the predictions of the fiber orientation evolution equation proposed by Folgar and Tucker. (RDC 12/15/2010)
Review Articles
Nanotechnology in plastic food-contact materials
(3719–3738) Journal of Applied Polymer Science 122 #6 (2011)
Hatzigrigoriou and Papaspyrides of the National Technical University of Athens, Greece review the application of nanotechnology in the polymer food-packaging. Emphasis is placed on the benefits of polymer nanocomposite materials in terms of their improved mechanical and processability properties but also in terms of more packaging-oriented attributes, such as enhanced barrier properties. In addition, nanotechnology is expected to introduce some novel and beneficial characteristics to plastic packaging materials. These characteristics include the induction of antimicrobial properties, oxygen scavenging, enzyme immobilization, and sensing of food conditions. Besides these novel properties, the need to explore the potential health impact of nanoparticles is also discussed, with a focus on the possibility of nanocomponent migration into the packaged foodstuff. (RDC 9/7/2011)
Current issues in research on structure–property relationships in polymer nanocomposites
(3321-3343) Polymer 51 #15 (2010)
Jancar et al describes the additionb of nanoparticles with large specific surface area to polymer matrices leads to amplification of a number of rather distinct molecular processes resulting from interactions between chains and solid surfaces. This results in a “non-classical” response of these systems to mechanical and electro-optical excitations when measured on the macroscale. There is also the tendency for the particles to associate into extended structures that can dominate the rheological, viscoelastic and mechanical properties of the nanocomposite so that thermodynamic factors that effect nanoparticle dispersion can be crucially important. Research on nanocomposites formed from block copolymers and nanoparticles offers huge promise in molecular electronics and photovoltaics. (RDC 12/22/2010)
Comments
Thanks for these comments.
Thanks for these comments. It reinforces my opinion there will be many new applications for nanocomposites as we become more familiar with its effects. (RDC 9/16/2009)
Use of nano thickness high
Use of nano thickness high surface area (>10exp2 meters/gram)materials in modifying viscosity of fluids is well known. Non-drip ceiling paints, thickened thermoset monomers, and many similar coatings applications are specific examples.
The newer uses for nano additives are mainly in the barrier area so far. In order for a solid plastic to burn, it is felt that it must be heated and converted to a gas. Both heat transmission and gas flow are reduced in the presence of thin (nano) plates of various high melting solids. This is the basis of many new FR applications.
The use of thin plates as additives or in coatings will reduce gas transmission rates. This idea is utilized in tennis ball coatings to increase use life and in soda bottles to prolong shelf life.