Nanocomposites
Figure 1 shows some of the proposed applications of nanocomposites. Examples of projects in this area include: Nanocomposites for Automotive, Aerospace and Defense Structures; Polymer Nanocomposite Foams; Conductive Nanocomposites for Electronic Packaging, Corrosion Protection, Energy Storage and Conversion; Nanocomposites for Optic Applications; Nanofiber Nests for Tissue Engineering; Nanofiber Array for Biosensing; and Life Cycle Analysis of Nanoparticles and Nanocomposites. Because of space limitations, only the first three projects are introduced here. Nanoparticles and nanocomposites developed can serve as functional materials needed in the Photonics and Biomedical Devices application areas.
• Conventional Composites with Nanocomposite Matrices We propose to improve targeted properties of polymeric resins through the controlled dispersion of functionalized nano-constituents, for applications in advanced fiber-filled composites. Traditional advanced organic-matrix-based carbon fiber composites appear to have matured with respect to material properties. While their in-plane, fiber-dominated properties make these composites highly desirable as compared to metals, their through-the-thickness or z-axis properties are limited by the performance of the matrix resin, thus restricting their use. Nanostructured materials open a new paradigm wherein matrix resins can be tailored to enhance composite properties of interest, just as fiber orientation is used now to tailor current advanced composites. In the near term, we will focus on the use of layered silicates and vapor-grown CNF to introduce beneficial properties to a wide variety of thermoplastic and thermosetting polymer resins for advanced fiber-filled composite applications. Potential applications/solutions offered by multifunctional nanostructured materials in conventional fiber reinforced composites include high damage tolerance, thermal conductivity, electrical conductivity and service temperature; low coefficient of thermal expansion (CTE); and better barrier properties and surface finish. The ability to engineer the properties of the matrix is crucial to meeting the performance requirements of future automotive and aerospace systems. While these applications will drive the technology development, the payoff will encompass nanocomposites applications in all market sectors. The aerospace market is focused primarily on high-performance applications while the automotive and commercial markets are focused on improved performance at the lowest possible cost. Conventional composite processing methods such as wet lay-up, autoclave cure, compression molding, filament winding, or liquid molding processes such as resin transfer molding and resin film infusion are all possible using a nanocomposite matrix.
(b) Polymer Nanocomposite Foams Plastic foams are widely used for thermal insulation of houses and buildings, packaging, cushions and absorbents. Thermal insulation alone has a worldwide market of more than $2 billion annually. Due to their role in ozone depletion, halogenated blowing agents, such as CFC and HCFC will be discontinued by 2010 according to the Montreal Protocol. However, when alternative blowing agents such as CO 2 are used with current manufacturing technologies, foams of significantly lower thermal performance result because CO 2 (owing to its much smaller molecular size than CFC) diffuses too fast into the polymer. Furthermore, plastic foams have the drawback of poor mechanical strength because the cell wall is only around 1 micron thick. OSU proposes to use nanoparticles such as layered silicates, nano-layered graphite and CNF to strengthen plastic foams. The plate-like silicates can improve the gas barrier property of the polymer and thus control the diffusion of CO 2 during foaming while the nano-graphite can absorb infrared to enhance the insulation R-value of the foam. Doubling the R-value of PS foams can save approximately 100 trillion BTUs (more than $1 billion) annually of heating energy in the US . OSU will develop new processing schemes to control the dispersion and orientation of the nanoparticles in the foam to optimize the foam morphology for improved thermal and mechanical performance. In-line ultrasonic devices can also be added to better control the particle dispersion, cell size, and density of the foam. More advanced applications include microcellular foams with superior strength-to-weight ratio, EMI shielding, and high service temperature for electronic packaging, and light weight automotive body panels.
(c) Nanocomposite Films for Electronics Packaging, Corrosion Protection, Energy Storage and Conversion Telecommunication electronics in remote areas are usually housed in sealed metal boxes to protect them from hostile environments such as heat, dust and humidity. Since the power efficiency of telecommunication electronics is very low (less than 10%) a majority of the energy is turned into heat in the box. This is very undesirable in high-heat areas. Polymer films with different functional properties will be laminated to produce a multifunctional polymer film. CNF will be used to provide EMI shielding and thermal transport to the laminated film. To take this process and product to commercialization, WCI funds are requested for a blown-film apparatus and a film laminator to fabricate the multifunctional nanocomposite films. Although organic photovoltaics (PV) have been around for some time, the use of polymeric materials in solar cells is quite new. Polymeric PV devices offer the potential of low cost, simplicity in fabrication, and inherent flexibility. The initial photovoltaic heterojunctions, based on conjugated polymers, had very low incident photon-to-current conversion efficiencies (IPCE). For solar cells of such an architecture the IPCE is limited by the efficiency of (1) photoexcitation of electron-hole pairs (or excitons), (2) charge separation at the p/n junction interface, (3) charge transport to the collecting electrodes, and (4) ohmic contact between the electrodes and the polymers.
Other Research Areas
