Thesis--Lund Institute of Technology, 1993.

Thesis--Lund Institute of Technology, 1993.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2007. / Rosen, David, Committee Chair ; O'Connor, Jerry, Committee Member ; Fedorov, Andrei, Committee Member.

abstract: This thesis elaborates the application of carbon nanotubes (CNTs) and it is discussed in two parts. In the first part of the thesis, two types of CNTs inks for inkjet materials printer are prepared. They are both chemical stable and printable, effective and easily made. The sheet resistance of printed films decreases exponentially as the number of layers increases. In the second part of this study, CNTs/ZnO composite structures are fabricated to understand the electronic and optical properties. The materials were deposited by two different methods: drop-drying and RF magnetic sputtering system on flexible polymer substrates. To further increase the conductivity of the various layers of deposited CNTs films, electrical and optical characterizations are also done. This study establishes CNTs as a multi-functional semitransparent conductor, which can be deposited at room-temperature with other transparent conductive oxide (TCO) composites for application in flexible electronics and printed circuit and sensors. / Dissertation/Thesis / M.S. Materials Science and Engineering 2012

Yes / Thermal ink-jet printing (TIJP) is shown to be a rapid (minutes) method with which to prepare pharmaceutical co-crystals; co-crystals were identified in all cases where the co-formers could be dissolved in water and/or water/ethanol solutions.

Published Article / This paper surveys the current state and capabilities of Three Dimensional Printing (3DP). Based on its technical background - the ink jet printing as known from the printer and plotter industry - a classification structure has been developed and proposed. Different printing techniques and process concepts, together with their advantages and limitations are described and analysed. A large variety of manufacturing applications such as rapid pattern making and rapid tooling using the 3DP process directly or as core technology, as well as further implications in design and engineering analysis, medicine, and architecture are presented and evaluated. Some research issues are also discussed. An attempt, based on the state of the art, to show weaknesses and opportunities, and to draw conclusions about the future of this important process wraps up this paper.

During the operation of phase-change ink-jet printers a bubble formation phenomenon often occurs. These bubbles are detrimental to the operation of the printer and substantial efforts are made to remove them. The objective of this research was 1: to develop a fundamental understanding of how bubble or void formation occurs during the phase-change process, and, 2: to develop a simple computer model to simulate this behavior which can then be used as a tool for better design of print-head geometries. Preliminary experimental work indicated the void formation to be a result of the density change accompanying the phase-change process. The commercial numerical code, Flow 3-D, was used to model the phase-change process in print-head geometries and substantiate certain simplifying assumptions. These assumptions included the effect of convection on the process and the effect of the varying material properties. For channel sizes less than 0.5 cm the phase-change process was found to be a pure conduction process. Convection effects are thus negligible and can be eliminated from the model. The variability of density, specific heat and thermal conductivity must be included in the model, as they affect the phase-change process dramatically. Specific heat is the most influential of the properties and determines, along with the conductivity, the rate at which the phase change takes place. The density must be included since it is directly linked to the void formation. / Graduation date: 1994

In this work the methodology is developed to study spreading and penetration of a custom ink-jet ink formulation, containing hydrophobic cationic crystal violet dye, ethoxylated surfactant, and ink solvent marked by lithium salt. With a new technique utilizing Time-of-Flight Secondary Ion Mass Spectrometry imaging, the ink component distribution and its effect on print quality of uncoated and coated papers are evaluated. High spatially resolved images obtained by ToF-SIMS illustrate differentiation of individual ink components, with ink solvent spreading more than the dye in all paper samples. Uncoated papers show greater and more irregular spreading leading to poor edge definition and poor print quality. Large separation of the dye from the solvent in the vertical direction of multipurpose and photo glossy ink-jet paper suggests a step-wise progression of ink penetration: ink flows through a more porous structure in the x-direction before advancing to the next sublayer in the z-direction of paper.

In this work the methodology is developed to study spreading and penetration of a custom ink-jet ink formulation, containing hydrophobic cationic crystal violet dye, ethoxylated surfactant, and ink solvent marked by lithium salt. With a new technique utilizing Time-of-Flight Secondary Ion Mass Spectrometry imaging, the ink component distribution and its effect on print quality of uncoated and coated papers are evaluated. High spatially resolved images obtained by ToF-SIMS illustrate differentiation of individual ink components, with ink solvent spreading more than the dye in all paper samples. Uncoated papers show greater and more irregular spreading leading to poor edge definition and poor print quality. Large separation of the dye from the solvent in the vertical direction of multipurpose and photo glossy ink-jet paper suggests a step-wise progression of ink penetration: ink flows through a more porous structure in the x-direction before advancing to the next sublayer in the z-direction of paper.

An imaging system was developed to visualize Drop-on-Demand (DOD) inkjet drop formation and impaction on substrate over drop sizes and impaction speeds of the magnitudes encountered in applications of inkjet printing. Using a pulsed laser, a low-speed charge-coupled-device (CCD) camera, and signal generators, the imaging system based on flash photography was used to capture sharp images with a temporal resolution of 200 ns and a spatial resolution of 0.81 micron/pixel. First, the dynamics of DOD drop formation was studied experimentally. The effects of the driving signal, which controls the piezoelectric transducer that produces the pressure pulse to drive the liquid from the reservoir through the orifice, have been examined along with those of liquid properties. The main stages of DOD drop formation, including ejection and stretching of liquid, pinch-off of liquid thread from the nozzle exit, contraction of liquid thread, breakup of liquid thread into primary drop and satellites, and recombination of primary drop and satellites, are analyzed. A necessary condition for the recombination of the primary drop and satellite and the limit for liquid thread length without breakup during contraction are proposed. Second, using the visualization system coupled with a motorized stage, micron-drop impaction on a smooth substrate was investigated over a regime of We and Oh typical for inkjet printing applications. The results indicate that scaling of micron-drop impaction from millimeter-drop impaction, based on dimensionless numbers (Oh, We and cos ), is valid. The predictions of maximum spreading ratio by six existing models agree well with experimental values for high-We impaction, but not for low-We and low-contact-angle impactions; however, the model of Park et al. predicts well for high- and low-We impaction due to its inclusion of spontaneous spreading dissipation. Fingering and splashing do not occur in the micron drop impaction on either dry solid substrates or a pre-existing liquid layer. The drying time of a micron drop deposited on a substrate is less than one second and increases as the contact angle of the drop on the substrate increases.