Conventional energetic materials which are based on monomolecular compounds such as trinitrotoluene (TNT) have relatively low volumetric energy density. The energy density can be significantly enhanced by the addition of metal particulates. Among all metals, aluminum is popular because of its high oxidation enthalpy, low cost, and relative safety. Micron-sized aluminum particles, which have relatively high ignition temperatures and burning times, have been most commonly employed. Ignition of micron-sized aluminum particles is typically achieved only upon melting of the oxide shell at 2350 K, thereby resulting in fairly high ignition delay. Novel approaches to reduce the ignition temperatures and burning times and enhance the energy content of the particle are necessary. Recently, there has been an enormous interest in nano-materials due to their unique physicochemical properties such as lower melting and ignition temperatures and shorter burning times. Favorably, tremendous developments in the synthesis technology of nano-materials have also been made in the recent past. Several metal-based energetic materials with nano-sized particles such as nano-thermites, nano-fluids, and metalized solid propellants are being actively studied. The “green” reactive mixture of nano-aluminum particles and water/ice mixture (ALICE) is being explored for various applications such as space and underwater propulsion, hydrogen generation, and fuel-cell technology. Strand burning experiments indicate that the burning rates of nano-aluminum and water mixtures surpass those of common energetic materials such as ammonium dinitramide (ADN), hydrazinium nitroformate (HNF), and cyclotetramethylene tetranitramine (HMX). Sufficient understanding of key physicochemical phenomena is, however, not present. Furthermore, the most critical parameters that dictate the burning rate have not been identified. A multi-zone theoretical framework is established to predict the burning properties and flame structure by solving conservation equations in each zone and enforcing the mass and energy continuities at the interfacial boundaries. An analytical expression for the burning rate is derived and physicochemical parameters that dictate the flame behavior are identified. An attempt is made to elucidate the rate-controlling combustion mechanism. The effect of bi-modal particle size distribution on the burning rate and flame structure are investigated. The results are compared with the experimental data and favorable agreement is achieved. The ignition and combustion characteristics of micron-sized aluminum particles can also be enhanced by replacing the inert alumina layer with favorable metallic coatings such as nickel. Experiments indicate that nickel-coated aluminum particles ignite at temperatures significantly lower than the melting point of the oxide film, 2350 K due to the presence of inter-metallic reactions. Nickel coating is also attractive for nano-sized aluminum particles due to its ability to maximize the active aluminum content. Understanding the thermo-chemical behavior of nickel-aluminum core-shell structured particles is of key importance to both propulsion and material synthesis applications. The current understanding is, however, far from complete. In the present study, molecular dynamics simulations are performed to investigate the melting behavior, diffusion characteristics, and inter-metallic reactions in nickel-coated nano-aluminum particles. Particular emphasis is on the effects of core size and shell thickness on all important phenomena. The properties of nickel-coated aluminum particles and aluminum-coated nickel particles are also compared. Considerable uncertainties pertaining to the ignition characteristics of nano-aluminum particles exist. Aluminum particles can spontaneously burn at room temperature, a phenomenon known as pyrophoricity. This is a major safety issue during particle synthesis, handling, and storage. The critical particle size below which nascent particles are pyrophoric is not well known. Energy balance analysis with accurate evaluation of material properties (including size dependent properties) is performed to estimate the critical particle size for nascent particles. The effect of oxide layer thickness on pyrophoricity of aluminum particles is studied. The ignition delay and ignition temperature of passivated aluminum particles are also calculated. Specific focus is placed on the effect of particle size. An attempt is made to explain the weak dependence of the ignition delay on particle size at nano-scales.

This thesis presents a Microwave Plasma Assisted Spray Deposition (MPASD) system design, characterization, and application to produce nano-sized particle coatings of metal oxides. A commercially available rectangular waveguide microwave power delivery system is utilized to initiate and sustain the plasma discharge within the customized plasma applicator where micron-sized droplets of a metal ion solution are heated to evaporate the solvent and thermally process the resulting nano-sized particles. The investigation of optimum conditions for oxygen, argon, and air plasma ignition in the MPASD system was presented. Measured electron temperature of the plasma was between 6000K and 40000K for the plasma conditions used in the MPASD process. Successful deposition of Y2O3:Eu nano-particles using the MPASD system was achieved. MPASD process allows control of the particle's properties, shown through XRD and photoluminescence studies of the Y2O3:Eu coatings. The MPASD process settings effect on particles activated doping concentration and, as a result, its photoluminescence was shown.

Naturally occurring biological nanoparticles (BNPs) and synthetic nanoparticles have a significant role in a wide range of biomedical applications. For instance, direct detection of BNPs, such as viruses, can provide new methods of viral diagnostics while synthetic particles can be used as labels to indirectly detect biomarkers for drug discovery. Therefore, developing advanced tools for nanoparticle detection has gained popularity in biotechnological research. One of the most exciting recent developments in BNP detection has been single particle (or digital) counting of individual particles which offers unprecedented sensitivity levels. However, standard optical techniques face a significant challenge for nanoparticle detection, due the weak optical contrast of sub-wavelength particles. Interferometric microscopy, overcomes the limitations imposed by particle size which allows for visualizing unresolved (diffraction-limited) optical signatures of sub-wavelength particles. Single-particle interferometric reflectance imaging sensor (SP-IRIS), is a widefield microscopy platform, developed by our group over the last years. SP-IRIS uses interferometric enhancement and a layered substrate to increase the optical contrast for the target particles of interest. While this microscopy technique has shown remarkable sensitivity levels for numerous applications including detection of viral particles and nucleic acids, it has remained a specialty tool due to the utilization of z-scan measurements for extracting the optical signature of particles. The z-scan measurements that consist of multiple frames acquired at different focal positions impose two major drawbacks. The first is the requirement of repeatable and high resolution scanning optics and the second is the time and computational processing power required to analyze the image stacks. In this thesis we describe a novel imaging method termed `pixel-diversity‘ IRIS (PD-IRIS), which aims to provide a more practical detection method for nanoparticles by eliminating the need for acquiring z-stacks. PD-IRIS is built upon SP-IRIS, however it introduces a paradigm shift for encoding the necessary optical signature of target particles. PD-IRIS compresses the relevant optical information within a single image frame rather than an image stack. This is achieved by using camera sensors that simultaneously record multiple spectral or polarization channels. Therefore, a single image can record distinct spectral responses of target particles with respect to different excitation wavelengths (multi-spectral PD-IRIS) or the distinct scattering characteristics with respect to polarization (polarization PD-IRIS). This dissertation presents a rigorous study for both PD-IRIS modes and demonstrates the practical applications of nanoparticle detection with proof-of-concept measurements. / 2024-01-16T00:00:00Z

L'objectif de ce travail est de développer l'utilisation de la biomasse ligno-cellulosique dans le domaine des matériaux. Ce travail explore trois voies différentes d'utilisation de la ligno-cellulose afin de balayer un large spectre de constituants et de matériaux finaux. La première voie concerne l'incorporation de fibres naturelles dans la fabrication de panneaux utilisant la lignine comme adhésif. Des améliorations dans la fabrication de ces panneaux de fibres ont été apportées, par traitement chimique ou ajout de nouveaux compatibilisants, permettant un renforcement des propriétés mécaniques. La seconde voie a consisté à développer un procédé original de mise en forme sous haute pression testé et mis en place sur du coton dans le but d'obtenir des objets tridimensionnels sans étape de dissolution/régénération de la cellulose. Une fois le protocole défini, les effets des paramètres de mise en forme et de la variété de coton sur la microstructure et les propriétés mécaniques des objets en coton compressé ont été étudiés. Enfin, une troisième voie à consisté à élaborer des matériaux nanocomposites à partir d'hydroxydes double lamellaire modifiés par la lignine (HDL/LS). L'utilisation de cette nanocharge dans l'amidon a montré une capacité de renforcement pour un faible taux de charge. Ce composite amidon-(HDL/LS) a ainsi été utilisé avec une matrice polyéthylène afin d'augmenter la part renouvelable de la matrice sans diminuer significativement ses propriétés mécanique. Ce travail permet d'envisager des développements futurs pour ces différents matériaux développés et offre ainsi de nouvelles possibilités d'utilisation de la biomasse ligno-cellulosique dans l'élaboration de matériaux techniques. / This work aims at developing new ligno-cellulosic biomass based materials as a way for giving added value to this raw material. This study aimed at developing three different new ways of using ligno-cellulosic components to get a large overview of the possible technical materials. The first way deals with the preparation of natural fibres filled lignin fibreboard panels. Improvements in panels forming have been achieved by using either chemical treatment or novel compatibilisation to improve the strength of the prepared fibreboards. In a second way, an original forming process by high pressure has been tested and carried out on cotton fibres in order to produce 3D objects without dissolution/coagulation processes of cellulose. After setting up the forming procedure, effects of process parameters and cotton variety on microstructures and mechanical properties of highly compressed cotton have been studied. Finally, a third way was the study of new nanocomposites made of layered double hydroxide modified by lignin (LDH/LS). Using such nanofillers into thermoplastic starch turned out to be an efficient solution to reinforce mechanical properties with low nanofillers loading. This starch-(LDH/LS) nanocomposite was also blended with polyethylene to increase the bio-content without a degradation of the mechanical properties. This study is an advanced basis for a further development of these three different materials and offers a broad range of applications suitable for the preparation of new technical materials.

To reduce electronics packaging lead time and potentially to reduce manufacturing cost, an innovative packaging process targeting rapid package prototyping (RPP) has been developed. The developed RPP process, which is based on a data-driven chip-first approach, provides electrical functionality as well as form factors for micro-systems packages. The key component of the RPP process is the nano-particle silver (NPS) interconnect. However, NPS has not yet been adequately proven for use in electronics packaging applications. Moreover, its adhesion to electronics packaging materials such as polyimide, benzocyclobutene (BCB), copper, and aluminum is found to be weak. Thus, improving the adhesion strength of NPS will be a key issue for reliable package prototypes with NPS interconnects. In this research, the adhesion of NPS to substrate materials is found to be attributed to particle adhesion and more specifically, van der Waals forces. An adhesion model based on the van der Waals force is suggested in order to predict NPS adhesion strength to packaging materials. A new adhesion test method that is based on a die shear test and a button shear test is developed to validate the NPS adhesion prediction model. The newly developed adhesion test method is generic in nature and can be extended to other thin films' adhesion tests. The NPS adhesion model provides a general and explicit relation between NPS tensile bond strength and adhesion factors such as substrate hardness, adhesion distance, van der Waals constant, and particle diameter. The NPS adhesion model is verified as a first order adhesion model using experimental data from seventeen packaging materials. Substrate hardness is identified as a primary factor in NPS adhesion. Adhesion distance and van der Waals constant are also significant in organic and inorganic materials. Diffusion or other interfacial reaction between NPS and metal substrates such as copper and silver seems to exist. Finally, guidelines to improve the adhesion strength of NPS are suggested based on the adhesion model and on external adhesion factors such as Silane coupling agents and plasma treatment.

The interaction of an evanescent wave and plasmonic nanostructures are simulated in Finite Element Method. Specifically, the optical absorption cross section (Cabs) of a silver nanoparticle (AgNP) and a gold nanoparticle (AuNP) in the presence of metallic (gold) and dielectric (silicon) atomic force microscope (AFM) probes are numerically calculated in COMSOL. The system was illuminated by a transverse magnetic polarized, total internally reflected (TIR) waves or propagating surface plasmon (SP) wave. Both material nanoscale probes localize and enhance the field between the apex of the tip and the particle. Based on the absorption cross section equation the author was able to demonstrate the increment of absorption cross section when the Si tip was brought closer to the AuNP, or when the Si tip apex was made larger. However, the equation was not enough to predict the absorption modification under metallic tips, especially for a AgNP's Cabs; neither it was possible to estimate the optical absorption based on the localized enhanced field caused by a gold tip. With the help of the driven damped harmonic oscillator equation, the Cabs of nanoparticles was explained. In addition, this model was applicable for both TIR and Surface Plasmon Polaritons illuminations. Fitting the numerical absorption data to a driven damped harmonic oscillator (HO) model revealed that the AFM tip modifies both the driving force (F0), consisting of the free carrier charge and the driving field, and the overall damping of the oscillator beta. An increased F0 or a decreased beta will result in an increased Cabs and vice versa. Moreover, these effects of F0 and beta can be complementary or competing, and they combine to either enhance or suppress absorption. Hence, a significantly higher beta with a small increment in F0 will result in an absorption suppression. Therefore, under a Si tip, Cabs of a AuNP is enhanced while Cabs of a AgNP is suppressed. In contrast, a Au tip suppresses the Cabs for both Au and Ag NPs. As an extension of this absorption model, further investigation of the guided mode and a close by nanostructure is proposed, where the scattered wave off the structure attenuates the guided mode with destructive interference.

The new generation of three roll mills is able to monitor occurring process loads while dispersion. This paper focuses on the interpretation of the gathered data to find criteria quantifying the dispersion state online. The aim is process time reduction. We used impedance spectroscopy to identify the dispersion state and correlated it with the occurring process loads. The dispersion process of a wide spectrum of carbon based nano particles, namely carbon black, single walled carbon nanotubes, multi walled carbon nanotubes, a few-layer graphene powder, electrochemically exfoliated graphite and a functionalized electrochemically exfoliated graphite was investigated. The filler content was varied along the material’s electrical percolation threshold. The criteria found led to a reduction of processing time and revealed the prevalent mechanisms during dispersion.

abstract: The fuel cell is a promising device that converts the chemical energy directly into the electrical energy without combustion process. However, the slow reaction rate of the oxygen reduction reaction (ORR) necessitates the development of cathode catalysts for low-temperature fuel cells. After a thorough literature review in Chapter 1, the thesis is divided into three parts as given below in Chapters 2-4. Chapter 2 describes the study on the Pt and Pt-Me (Me: Co, Ni) alloy nanoparticles supported on the pyrolyzed zeolitic imidazolate framework (ZIF) towards ORR. The Co-ZIF and NiCo-ZIF were synthesized by the solvothermal method and then mixed with Pt precursor. After pyrolysis and acid leaching, the PtCo/NC and PtNiCo/NC were evaluated in proton exchange membrane fuel cells (PEMFC). The peak power density exhibited > 10% and 15% for PtCo/NC and PtNiCo/NC, respectively, compared to that with commercial Pt/C catalyst under identical test conditions. Chapter 3 is the investigation of the oxygen vacancy (OV) effect in a-MnO2 as a cathode catalyst for alkaline membrane fuel cells (AMFC). The a-MnO2 nanorods were synthesized by hydrothermal method and heated at 300, 400 and 500 ℃ in the air to introduce the OV. The 400 ℃ treated material showed the best ORR performance among all other samples due to more OV in pure a-MnO2 phase. The optimized AMFC electrode showed ~ 45 mW.cm-2, which was slightly lower than that with commercial Pt/C (~60 mW.cm-2). Chapter 4 is the density functional theory (DFT) study of the protonation effect and active sites towards ORR on a-MnO2 (211) plane. The theoretically optimized oxygen adsorption and hydroxyl ion desorption energies were ~ 1.55-1.95 eV and ~ 0.98-1.45 eV, respectively, by Nørskov et al.’s calculations. All the configurations showed oxygen adsorption and hydroxyl ion desorption energies were ranging from 0.27 to 1.76 eV and 1.59 to 15.0 eV, respectively. The site which was close to two Mn ions showed the best oxygen adsorption and hydroxyl ion desorption energies improvement with the surface protonation. Based on the results given in Chapters 1-4, the major findings are summarized in Chapter 5. / Dissertation/Thesis / Doctoral Dissertation Systems Engineering 2019

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