Polymer Nanocomposites
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Nanocomposites
Karen I. Winey and Richard A. Vaia, Guest Editors Abstract Polymer nanocomposites (PNCs)—that is, nanoparticles (spheres, rods, plates) dispersed in a polymer matrix—have garnered substantial academic and industrial interest since their inception, circa 1990. This is due in large part to the incredible promise demonstrated by these early efforts: PNCs will not only expand the performance space of traditional filled polymers, but introduce completely new combinations of properties and thus enable new applications for plastics. Low volume additions (1–5%) of nanoparticles, such as layered silicates or carbon nanotubes, provide property enhancements with respect to the neat resin that are comparable to those achieved by conventional loadings (15–40%) of traditional fillers. The lower loadings facilitate processing and reduce component weight. Most important, though, is the unique value-added properties not normally possible with traditional fillers, such as reduced permeability, optical clarity, self-passivation, and increased resistance to oxidation and ablation. These characteristics have been transformed into numerous commercial successes, including automotive parts, coatings, and flame retardants. This issue of the MRS Bulletin provides a snapshot of these exemplary successes, future opportunities, and the critical scientific challenges still to be addressed for these nanoscale multiphase systems. In addition, these articles provide a perspective on the current status and future directions of polymer nanocomposite science and technology and their potential to move beyond additive concepts to designed materials and devices with prescribed nanoscale composition and morphology.
Introduction Polymers have been a part of life since the beginning of humankind. From tar and shellac, tortoise shell and horns, to today’s synthetic offerings such as polyolefins, epoxies, and engineering resins, polymers provide crucial materials for construction, commerce, transportation, and entertainment across the globe. Estimates of global polymer production range from 250 billion pounds to more than 400 billion pounds (approximately 114–181 billion kg) annually. In the majority of their diverse applications, polymeric materials are not chemically or molecularly homogenous but are multicomponent systems. By adding fillers, such as minerals, ceramics, metals, or even air, materials scientists can generate an infinite variety of materials with unique physical properties and competitive production costs. For example, adding filler to a commodity thermoplastic such as polypropylene can achieve performance levels that would otherwise require a much more
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expensive engineering plastic. Similarly, combining different polymers to form a polymer blend or resin can increase the value of existing polymers. Polymer nanocomposites incorporate a new spectrum of fillers that extend the function and utility of polymers while maintaining the manufacturing and processing flexibility inherent to plastics, thermosets, and resins. In p
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