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- Title
- Processing, Characterization and Performance of Carbon Nanopaper Based Multifunctional Nanocomposites.
- Creator
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Liang, Fei, Gou, Jihua, Su, Ming, Fang, Jiyu, Orlovskaya, Nina, Xu, Yunjun, University of Central Florida
- Abstract / Description
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Carbon nanofibers (CNFs) used as nano-scale reinforcement have been extensively studied since they are capable of improving the physical and mechanical properties of conventional fiber reinforced polymer composites. However, the properties of CNFs are far away from being fully utilized in the composites due to processing challenges including the dispersion of CNFs and the viscosity increase of polymer matrix. To overcome these issues, a unique approach was developed by making carbon nanopaper...
Show moreCarbon nanofibers (CNFs) used as nano-scale reinforcement have been extensively studied since they are capable of improving the physical and mechanical properties of conventional fiber reinforced polymer composites. However, the properties of CNFs are far away from being fully utilized in the composites due to processing challenges including the dispersion of CNFs and the viscosity increase of polymer matrix. To overcome these issues, a unique approach was developed by making carbon nanopaper sheet through the filtration of well-dispersed carbon nanofibers under controlled processing conditions, and integrating carbon nanopaper sheets into composite laminates using autoclave process and resin transfer molding (RTM). This research aims to fundamentally study the processing-structure-property-performance relationship of carbon nanopaper-based nanocomposites multifunctional applications: a) Vibrational damping. Carbon nanofibers with extremely high aspect ratios and low density present an ideal candidate as vibrational damping material; specifically, the large specific area and aspect ratio of carbon nanofibers promote significant interfacial friction between carbon nanofiber and polymer matrix, causing higher energy dissipation in the matrix. Polymer composites with the reinforcement of carbon nanofibers in the form of a paper sheet have shown significant vibration damping improvement with a damping ratio increase of 300% in the nanocomposites. b) Wear resistance. In response to the observed increase in toughness of the nanocomposites, tribological properties of the nanocomposite coated with carbon nanofiber/ceramic particles hybrid paper have been studied. Due to high strength and toughness, carbon nanofibers can act as microcrack reducer; additionally, the composites coated with such hybrid nanopaper of carbon nanofiber and ceramic particles shown an improvement of reducing coefficient of friction (COF) and wear rate. c) High electrical conductivity. A highly conductive coating material was developed and applied on the surface of the composites for the electromagnetic interference shielding and lightning strike protection. To increase the conductivity of the carbon nanofiber paper, carbon nanofibers were modified with nickel nanostrands. d) Electrical actuation of SMP composites. Compared with other methods of SMP actuation, the use of electricity to induce the shape-memory effect of SMP is desirable due to the controllability and effectiveness. The electrical conductivity of carbon fiber reinforced SMP composites can be significantly improved by incorporating CNFs and CNF paper into them. A vision-based system was designed to control the deflection angle of SMP composites to desired values. The funding support from National Science Foundation and FAA Center of Excellence for Commercial Space Transportation (FAA COE CST) is acknowledged.
Show less - Date Issued
- 2012
- Identifier
- CFE0004569, ucf:49194
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004569
- Title
- Optical Fluid-based Photonic and Display Devices.
- Creator
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Xu, Su, Wu, Shintson, Li, Guifang, Moharam, M., Wu, Xinzhang, University of Central Florida
- Abstract / Description
-
Conventional solid-state photonic devices exhibit an ultra-high optical performance and durability, but minimal adaptability. Recently, optical fluid-based photonic and display devices are emerging. By dynamically manipulating the optical interface formed by liquids, the optical output can be reconfigured or adaptively tuned in real time. Such devices exhibit some unique characteristics that are not achievable in conventional solid-state photonic devices. Therefore, they open a gateway for...
Show moreConventional solid-state photonic devices exhibit an ultra-high optical performance and durability, but minimal adaptability. Recently, optical fluid-based photonic and display devices are emerging. By dynamically manipulating the optical interface formed by liquids, the optical output can be reconfigured or adaptively tuned in real time. Such devices exhibit some unique characteristics that are not achievable in conventional solid-state photonic devices. Therefore, they open a gateway for new applications, such as image and signal processing, optical communication, sensing, and lab-on-a-chip, etc. Different operation principles of optical fluid-based photonic devices have been proposed, for instance fluidic pressure, electrochemistry, thermal effect, environmentally adaptive hydrogel, electro-wetting and dielectrophoresis. In this dissertation, several novel optical fluid-based photonic and display devices are demonstrated. Their working principles are described and electro-optic properties investigated.The first part involves photonic devices based on fluidic pressure. Here, we present a membrane-encapsulated liquid lens actuated by a photo-activated polymer. This approach paves a way to achieve non-mechanical driving and easy integration with other photonic devices. Next, we develop a mechanical-wetting lens for visible and short-wavelength infrared applications. Such a device concept can be extended to longer wavelength if proper liquids are employed.In the second part, we reveal some new photonic and display devices based on dielectrophoretic effects. We conceive a dielectric liquid microlens with well-shaped electrode for fixing the droplet position and lowering the operating voltage. To widen the dynamic range, we demonstrate an approach to enable focus tuning from negative to positive or vice versa in a single dielectric lens without any moving part. The possibility of fabricating microlens arrays with different aperture and density using a simple method is also proposed. Furthermore, the fundamental electro-optic characteristics of dielectric liquid droplets are studied from the aspects of operating voltage, frequency and droplet size. In addition to dielectric liquid lenses, we also demonstrate some new optical switches based on dielectrophoretic effect, e.g., optical switch based on voltage-stretchable liquid crystal droplet, variable aperture or position-shifting droplet. These devices work well in the visible and near infrared spectral ranges. We also extend this approach to display and show a polarizer-free and color filter-free display. Simple fabrication, low power consumption, polarization independence, relatively low operating voltage as well as reasonably fast switching time are their key features.
Show less - Date Issued
- 2012
- Identifier
- CFE0004620, ucf:49943
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004620
