Conferences, Lectures, & Seminars
Events for January
-
PhD Defense
Fri, Jan 11, 2019 @ 10:00 AM - 12:00 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Speaker: Yijia Ma , Mork Family Department of Chemical Engineering and Materials Science, University of Southern California
Talk Title: Chemical Recycling of Amine/Epoxy Composites at Atmospheric Pressure
Abstract: Because of the increasing demand for lightweight structures in aerospace, automotive, and wind energy industries, the global market size for carbon fiber polymer composites is anticipated to reach $ 35 billion by 2020. Carbon fibers from end-of-life composites retain properties nearly equivalent to virgin fibers, yet few are recovered and/or reused due to a lack of viable recycling technologies. This absence of recovery/recycling is especially true for thermoset composites that undergo irreversible cure reactions. At the present juncture, composite recyclability is essential to the sustainability of the growing composite industry. Without a robust and effective method to recycle composites and complete the material life-cycle, these materials will not be able to compete with steel and aluminum in mass market applications, for which recycling rates are already high.
The objective of my research is to develop an effective chemical recycling method for cleavage of polymer matrices using moderate conditions (atmospheric pressure and moderate temperature) and safe chemicals that can recover near-virgin quality fibers and potentially useful polymer components. These features are critical to practical, large-scale composite recycling, but have not been reported to date. My investigation focuses on amine-cured epoxies, which is the most widely used polymer matrix in high-performance composites.
Findings indicated that acid digestion was an effective dissolution process for highly crosslinked amine/epoxy composites. Near-virgin quality carbon fibers in the original fabric form were recovered after digestion. The reaction mechanism for acid digestion was identified, and target catalysts were evaluated to accelerate the reaction rate. Furthermore, a parametric study that investigated the relationship between composite properties and matrix dissolution rate was performed, and key parameters affecting the dissolution rate were identified. Data showed that the major rate-limiting factor for acid digestion was the diffusion rate, rather than the chemical reaction rate. Two strategies to enhance the diffusion rate -“ pre-treatment and mechanical shredding -“ were evaluated, and both were effective. Lastly, I recovered the decomposed matrix residues from chemical solutions after acid digestion and demonstrated routes for reusing the matrix residues in virgin resin formulations, effectively closing the recycling loop.
Location: Hedco Pertroleum and Chemical Engineering Building (HED) - 116
Audiences: Everyone Is Invited
Contact: Karen Woo/Mork Family
-
Mork Family Department of Chemical Engineering and Materials Science Seminar - Distinguished Lecture Series
Tue, Jan 15, 2019 @ 11:00 AM - 12:00 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Speaker: Professor Susannah Scott, Department of Chemical Engineering , University of California - Santa Barbara
Talk Title: Modeling active sites in heterogeneous catalysts for olefin polymerization and metathesis
Abstract: Kinetic analysis and in situ spectroscopic methods have long been used to characterize catalysts, and are essential to our understanding of how these materials behave under reaction conditions. Recent explorations of simple and complex oxides as heterogeneous catalysts using a combination of unconventional non-isothermal kinetic methods and operando spectroscopies have revealed that active sites respond rapidly to variations in the redox environment. In particular, IR spectroscopy of adsorbed CO and X-ray absorption spectroscopy at the Pd K-edge were used to obtain complementary information about surface and the sub-surface states in PdOx nanoparticles during lean CO oxidation for three distinct activity regimes: low, intermediate and high conversion. A change in the oxidation state of surface Pd atoms coincides with a first-order kinetic phase transition associated with light-off and extinction. These findings inspired the redesign of simple oxide catalysts as complex oxides to stabilize the most active phase.
Host: Dr. Sharada
Location: John Stauffer Science Lecture Hall (SLH) - 100
Audiences: Everyone Is Invited
Contact: Karen Woo/Mork Family
-
PhD Defense
Tue, Jan 22, 2019 @ 11:00 AM - 12:00 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Speaker: Zhuofan Shi , PhD Candidate, Chemical Engineering
Talk Title: The Study of CO2 Mass Transfer in Brine and in Brine-Saturated Mt. Simon Sandstone and the CO2/Brine Induced Evolution of its Transport and Mechanical Properties
Abstract: Emissions of greenhouse gases are thought to contribute to global warming. Geological carbon sequestration (GCS) is currently considered a promising method to mitigate atmospheric CO2 and, thus, to potentially minimize climate change. In this approach, CO2 is injected into the subsurface and is trapped there by three main mechanisms, namely physical trapping, dissolution, and mineral precipitation.
The present work focuses on two important aspects of GCS. First, we study mass transfer and sorption phenomena in brine, which are the key two processes occurring during CO2 dissolution trapping in GCS. We employ pressure-decay experiments to measure CO2 solubility, and mass transfer in water/brine systems at elevated pressures of relevance to CO2 storage operations in saline aquifers together with modeling to delineate and interpret the experimental data. Accurate measurements and modeling of mass transfer in this context are crucial to an improved understanding of the long-term fate of CO2 that is injected into the subsurface for storage purposes. We demonstrate that simple 1-D interpretations based on diffusional transport alone can result in an overestimation of the uptake (diffusivity) by two orders of magnitude. The high-resolution 2-D numerical calculations, on the other hand, agree well with the experimental observations for conditions where natural convection contributes substantially to the overall mass transfer process.
We also study, in addition, rock-fluid interactions and their impact on the transport and mechanical properties of the host rock, which are phenomena relevant to CO2 mineral trapping during GCS. Specifically, the present study investigates the change in the flow-through characteristics, porosity, and the mechanical behavior of Mt. Simon Sandstone samples caused by exposure to brine/CO2. Our experiments show that the porosity of the Mt. Simon samples slightly increases after exposure to CO2/brine, while the permeability increases more substantially (depending on the confining pressure environment). Measurements of the flow-through pore size distribution (PSD) are indicative of significant changes occurring, consistent with the observed increases in permeability. Nitrogen adsorption tests (BET), before and after aging, show a significant loss of pore volume in the mesopore range that is indicative of clay dissolution. Weakening of the materials was observed based on the mechanical properties studied, a result that is consistent with the observed dissolution of clays that play a central role in the cementation of the quartz grains. Finally, the analysis of the brine compositions employed in the aging experiments reveals an increase in the concentration of most cations after incubation with the Mt. Simon cores. This is also consistent with mineral/clay dissolution, confirmed by the porosity, transport, and mechanical property measurements as well as electron microscopy analysis of the same samples.
Location: Hedco Pertroleum and Chemical Engineering Building (HED) - 303
Audiences: Everyone Is Invited
Contact: Karen Woo/Mork Family
-
Mork Family Department of Chemical Engineering and Materials Science Seminar - Distinguished Lecture Series
Tue, Jan 29, 2019 @ 04:00 PM - 05:20 PM
Mork Family Department of Chemical Engineering and Materials Science
Conferences, Lectures, & Seminars
Speaker: Professor Megumi Kawasaki , School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University
Talk Title: Processing of bulk nanostructured materials through the application of high-pressure torsion
Abstract: The processing of metals through the application of severe plastic deformation (SPD) has attracted much attention for the production of ultrafine-grained (UFG) metals and bulk nanostructured materials (BNM). Among the SPD techniques, high-pressure torsion (HPT) provides the potential for achieving true nanometer grains by processing metal disks under a high compressive pressure and concurrent torsion straining. These ultrafine grains in the bulk metals usually show superior mechanical and physical properties. Especially, the development of micro-mechanical behavior is observed after significant changes in microstructure after processing and it is of great importance for obtaining practical future applications of these UFG metals. Moreover, recent studies show the potential for using HPT for the rapid fabrication of nanocomposites. Accordingly, this presentation demonstrates the basic understanding of processing of UFG and BNM by HPT and the evolution of microstructure and mechanical properties after HPT on various metallic alloys and metal-matrix nanocomposites. Special emphasis is placed on demonstrating a simple and very rapid synthesis of metal-matrix nanocomposites by HPT at ambient temperature. These synthesized hybrid systems exhibit exceptionally high specific strength through deformation-induced diffusion and the simultaneous formation of a few different intermetallic compounds. These experimental findings suggest a considerable potential for making use of HPT for the introduction of UFG microstructure and fabrication of a wide range of hybrid materials.
Host: Dr. Kassner
Location: John Stauffer Science Lecture Hall (SLH) - 200
Audiences: Everyone Is Invited
Contact: Karen Woo/Mork Family