Browsing by Subject "Processing"
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Item Influence of layer thickness and nozzle temperature on the interlocking adhesion strength of additive manufactured multi-material interface(2022) Xue, Fangkai; Boudaoud, Hakim; Robin, Guillaume; Cruz Sanchez, Fabio A.; Daya, El MostafaAchieving adequate adhesion strength at multi-material interfaces is always a challenge in material extrusion additive manufacturing (MEAM), especially when the materials have very different chemical affinities. This study investigated the adhesion mechanism of multi-material interfaces in MEAM from a micro-geometric perspective. The vertically printed interface was found to have a smooth surface, while the horizontally printed interface had a micro-zigzag interlocking geometry. The formation of this micro-zigzag interlock is due to the switching of extruders during printing, which mechanically reinforces the interface adhesion strength. Using butt-joint tensile test and microscope observation, it was found that the geometry of this zigzag interlock is significantly influenced by the layer thickness, nozzle temperature and extruder offset. By optimizing the layer thickness and nozzle temperature, the interface adhesion strength between dissimilar materials was increased by 58.2% without significantly increasing the printing time or fabrication complexity.Item Multifunctional cyanate ester/MWNT nanocomposites : processing and characterization(2013-12) Lao, Si Chon; Moon, T. J. (Tess J.); Koo, Joseph H.Tomorrow’s lightweight, high-performance composite systems will be made of structures built with materials that have unprecedented intrinsic properties for performing a wide range of functions, such as EMI shielding, thermal management, flame resistance, lightning strike protection, acoustic damping, and health-monitoring. Current structures require parasitic components, e.g., metal strips, copper wire meshes, strain gauges, and heat sinks to provide these functions. By eliminating parasitic components, future high-performance multifunctional systems can achieve the intended objectives, while maintaining optimum weight, reliability, cost, and fuel efficiency. With the continuing growth of polymer composites in industries, such as aerospace, automotive, and wind energy, research and development on lightweight, high-performance composites that possess extraordinary properties for future multifunctional systems has generated considerable interest and excitement. Recent advances in nanomaterial synthesis and functionalization have shown that tailored property combinations are possible with reduced parasitic content to achieve multifunctionality. Cyanate ester (CE), a class of high-performance thermosetting resins (high T [subscript g], >250°C), has received considerable attention due to its good mechanical properties, thermal stability, flammability properties, ease of process, and volatile-free curing process. Multiwall carbon nanotubes were selected due to their unique combination of excellent mechanical, electrical, and thermal properties. The principal objective of this work is to determine the extent to which several different processing techniques will affect the MWNT dispersion and corresponding nanocomposite properties, such as thermal, flammability, mechanical, and electrical properties. A processing-structure-property relationship, as well as performance of this class of carbon-based CE nanocomposite, will be established. Therefore, a major scientific contribution of this study will be the development and characterization of a novel, multifunctional CE nanocomposite. Different mixing instruments, such as high shear mixer, ultrasonicator, planetary centrifugal mixer, etc. were used to disperse the nanotubes in the cyanate ester resin matrix. Microstructural morphology characterizations by SEM, STEM, and TEM show that various degrees of dispersions of MWNTs were obtained by the different mixing techniques. An attempt to quantify the MWNT dispersion was made. Electrical resistivity of samples processed by both stand mixer and three-roll mill passes the ESD requirement; however, the MWNT percolation thresholds by the two techniques are different. Thermal analysis shows that the addition of the Fe³+ catalyst or the coupling agent lowers the glass transition temperature and degrades the mechanical properties (e.g., storage modulus, tangent of phase angle delta) of the CE resin. On the other hand, processing techniques only affect the mechanical properties of the resin. Thermal stability of CE is only slightly affected by different processing techniques, as well as the addition of MWNTs. Much more significantly, flammability characterization shows that the incorporation of either the Fe³+ catalyst or the coupling agent substantially increases the peak heat release rate (PHRR) relative to the neat CE resin value.Item Study of information specific and relational processing through advertising messaging frameworks(2014-05) Barbeisch, Victoria Elizabeth; Eastin, Matthew S.Utilizing the information garnered from research on information processing in the two elaboration types (i.e., item-specific and relational processing) this research examines the influence of gender and advertising narrative effectiveness. Advertising effectiveness is determined by recall and perception from exposure to relational and item-specific developed narratives. Included are literature reviews, supporting data and analysis, results, discussion, and speculations of differing outcomes based on the study conducted.Item Towards an Automated Methodology for Optically Cured, High Thickness Composite Polymer Pastes: An Iso-based Approach for Large Area Additive Manufacturing(2022) Kerr, C.J.; Munguia Valenzuela, J.; Nixon-Pearson, O.; Forrest, M.; Gosling, P.D.Optically cured polymer composites can offer numerous advantages over thermally- processed composites. This is especially applicable with large beads generated using Large Area Additive Manufacturing (LAAM) extrusion. This paper proposes a low-cost, semi- automated, off-the-shelf desktop system to quickly and precisely cure 8 mm thick, glass-filled (di-)methacrylate composite specimens for three-point flexural testing. In the absence of a clear preparation method for specimens of this thickness, we integrate aspects of two existing ISO Standards: ISO 178:2019, and ISO 4049:2019, to provide a rapid and reliable basis for specimen preparation and flexure testing. We propose two distinct curing strategies and compare these in terms of the flexural performance of prepared specimens, and the total cure time. Flexural data is critical to understanding the structural performance of light-activated composite pastes; and the curing methodology can be applied to potential future technologies which involve high-speed in-situ curing, from direct part/feature repair to functional production.