Polymer/inorganic nanocomposites are composed of two or more physically distinct components with one or more average dimensions smaller than 100 nanometers
A multiphase compound in which one of the phases has a length scale in the nanometer range.
Composite materials where at least one dimension of the reinforcement is in the range of 1-100 nm.
From the structural point of view, the role of inorganic filler, usually as particles or fibers, is to provide intrinsic strength and stiffness while the polymer matrix can adhere to and bind the inorganic component so that forces applied to the composite are transmitted evenly to the filler. Meanwhile, the polymer matrix can also protect the surface of the filler from damage and keep the particle apart to hinder crack propagation.
Furthermore, aside from all these intrinsic physical properties of the components, nanocomposite materials can achieve much better properties than just the sum of its components as a result of interfacial interaction between the matrix and filler particles. It’s the nature and degree of such interactions that play a pivotal role on the characteristics of resulted nanocomposites such as solubility, optical properties, electrical and mechanical aspects, etc.
The general class of nanocomposite organic/inorganic materials is a fast growing area of research. Significant effort is focused on the ability to obtain control of the nanoscale structures via innovative synthetic approaches. The properties of nano-composite materials depend not only on the properties of their individual parents but also on their morphology and interfacial characteristics.
This rapidly expanding field is generating many exciting new materials with novel properties. The latter can derive by combining properties from the parent constituents into a single material. There is also the possibility of new properties which are unknown in the parent constituent materials.
For decades, mineral fillers, metals and fibers have been added to thermoplastics and thermosets to form composites. Compared to neat resins, these composites have a number of improved properties including tensile strength, heat distortion temperature and modulus. Thus for structural applications, composites have become very popular and are sold in billion-pound quantities. These filled thermoplastics are sold in even larger volumes than neat thermoplastics.
Furthermore, the volume of fillers sold roughly equals the volume of thermoplastic resin sold. Clearly, the idea of adding fillers to thermoplastics and thermosets to improve properties, and in some cases decrease costs, has been very successful for many years.
Thermoplastics have become part of the fabric of modern life. Billions of pounds of these materials are sold annually, and the rate of thermoplastic production is increasing. These materials are ubiquitous and found in homes, cars, offices, and a host of other places. Thermoplastics have grown in acceptance in our society because they perform well for their cost.
More recently, advances in synthetic techniques and the ability to characterize materials readily on an atomic scale have lead to interest in nanometer-size materials, e.g., grains, fibers and plates. They have dramatically increased surface area compared to conventional-size materials, and the chemistry of nanosize materials is altered in comparison to conventional materials.
Polymer nanocomposites combine composites and nanometer size materials. Thermoplastics filled with nanometer size materials have properties different from thermoplastics filled with conventional materials. Some of these properties, such as increased tensile strength, may be achieved by using higher conventional filler loading at the expense of increased weight and decreased gloss. Other properties, such as clarity or improved barriers, cannot be duplicated by filled resins at any loading.
Polymer nanocomposites were developed in the late 1980s by both commercial research organizations and academic laboratories. Toyota was the first company to commercialize these nanocomposites, and it used nanocomposite parts in one of its popular models for several years. Following Toyota's lead, a number of other companies also began investigating nanocomposites.
Most of the commercial interest in nanocomposites has been focused on thermoplastics. They can be broken into two groups: less expensive commodity resins and the more expensive (and higher performance) engineering resins. One of the goals of nanocomposites was to permit substitution of more expensive engineering resins with a less-expensive commodity resin nanocomposite. Substituting a nanocomposite commodity resin with equivalent performance as a more expensive engineering resin should yield overall cost savings. Using a strict definition of nanocomposites, i.e., any filler submicron in size, there already are significant volumes of nanocomposites being produced (probably more than 100 million pounds). However, the fillers, carbon black, fumed silica and calcium carbonate, do not alter the performance of the composite dramatically when compared to conventional size fillers. Furthermore, these materials have been known and used for decades. Often, particles used in composites are agglomerates of smaller particles. This was unknown until microscopy developed to the point where it could characterize these particles more fully.
Much of the research interest in nanocomposites was jump-started by the National Nanotechnology Initiative (NNI). More research money was provided by this initiative than was spent on the Human Genome Project. For example, NNI funding exceeded $600 million in 2003 and continues to increase.
The goals of the NNI have been adopted by many nanotechnology researchers (who are looking for funding, of course):
1. Research and technology development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1 nanometer to 100 nanometer range.
2. Creating and using structures, devices and systems that have novel properties and functions because of their small and/or intermediate size.
3. Ability to control or manipulate on the atomic scale; nanotechnology implies that new materials and applications are being developed to specifically exploit the properties found in this size range.
Consequently, this report excludes composites made from conventional materials, even if they are composed of particles that meet the strict dictionary size definition of nanoparticles.
At this point in time, there has been much less open commercial interest in thermoset nanocomposites compared to thermoplastics. Yet thermoplastics have been able to dominate a major coating market in a relatively short time frame.
Nanocomposites have proven to be more difficult to manufacture than first anticipated, but new materials in pilot plants and laboratories may be able to live up to much of their initial promise. Greater understanding of the chemistry driving the formation of nanocomposites has enabled researchers to discover practical production methods for these materials.
Nanocomposites offer improvements in several of the properties of thermoplastics including tensile strength, modulus, barrier and heat distortion temperature. If a nanocomposite could offer these improvements at no additional cost, then it quickly would replace a large percentage of unfilled thermoplastics. Unfortunately, improved performance of a nanocomposite compared to a thermoplastic comes with an increase in price.
Therefore, replacement will not come on a wholesale basis, but will take place in applications where improved performance of a nanocomposite justifies the price increase. Nanocomposites are not going to be commodity materials. They are specialty materials that will carry a price premium for the foreseeable future.
Since nanocomposites will not completely replace any particular unfilled resin, over the next 5 years, amounts of nanocomposites will be modest by thermoplastic standards. However, nanocomposites already are produced in multimillion-pound quantities and these applications should increase dramatically during the next half-decade.
This report summarizes and describes current nanocomposite products, and covers some of the future developments involving these materials. It also covers a number of applications for these nanocomposites, and estimates possible future markets for them.
Armed with this information, readers with business interests then can make sound judgments regarding marketing strategies, investment decisions, or strategic plans concerning markets for polymer nanocomposites. This report was written to be readily accessible for readers with a business background, but accuracy concerning the technical aspects of polymer nanocomposite manufacture has not been sacrificed.
This report features two types of polymer nanocomposites:
• Thermoplastic: these materials are broken into two major categories, i.e., commodity resins and engineering resins; the potential of polymer nanocomposite commodity resin is covered by filler types such as nanoclays, nanotubes and metal oxides.
• Thermoset nanocomposites: these have received less commercial interest during their development than have thermoplastic nanocomposites, but the materials have been more straightforward to produce.
The report is broken into five sections. First there is a technology overview that gives the broad details of polymer nanocomposites, along with some of their physical properties and methods of manufacture. Next there is an extensive description of the industry that is developing polymer nanocomposites including clay manufacturers, nanotube manufacturers, metal oxide filler manufacturers, thermoplastic resin producers, and compounders, along with company profiles. The products section covers nanocomposites by filler type, along with relevant resins for each nanocomposite. The report concludes with a market applications section that covers the likely trends over the next 5 years.