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Towards The Understanding Of The Effect Of Functional Monomers On Latex Particle Morphology Formed By Emulsion Polymerization, Amit Kumar Tripathi

Doctoral Dissertations

Emulsion polymerization is a multiphase reaction process and the overall kinetics depend on the reaction rates in both the aqueous and particle phases. The morphology development within composite latex particles is controlled by both kinetic and thermodynamic factors. Functional monomers like acrylic acid and 2-hydroxyethyl methacrylate are widely used in emulsion polymerization at low concentrations (usually < 10% to total monomers) to improve various properties like shear and freeze thaw stability of the latex, adhesion of the polymer to metal and paper, and to create the possibility for post-polymerization chemical modifications. These monomers are highly water soluble and very much more polar than the commonly used acrylate and styrene monomers. This dissertation deals with the effect of such functional monomers on the reaction kinetics during the emulsion polymerization and on the resulting morphology of the composite latex particles.

A detailed examination of the distribution behavior of vinyl acid and hydroxy (meth)acrylate functional monomers between the nonfunctional monomer phase and the aqueous phase is reported here. Due to the dimerization and multimer formation capabilities of vinyl acid and hydroxy (meth)acrylate monomer via hydrogen …

Syntheses And Characterizations Of Novel Organic Semiconductors, Yushu Li

Doctoral Dissertations

The desire for portable, flexible and affordable electronic devices provides the driving force for the development of new organic semiconductors. Organic semiconductors can be solution processed, potentially enabling high-rate fabrication of electronic devices on flexible substrates. Devices of interest include organic field effect transistors (OFETs), organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs). Research presented here has focused on the synthesis and characterization of three different classes of organic semiconductors: a water soluble pentacene, a disulfide-linked pentacene oligomer and several [60]fullerene-pentacene adducts. In addition, an aromatization reaction leading to bis(organothio)pentacenes has been systematically studied.

The first water soluble pentacene, …

Biaxial Stress Testing Of Ss-304l Microtubes By Axial Load And Internal Pressure, Peter William Ripley

Master's Theses and Capstones

The mechanical behavior and material properties of a Stainless Steel SS-304L microtube, with an OD of 2.40 mm and wall thickness of 160 µm, was investigated through uniaxial, isothermal, biaxial, and metallographic testing. The grain structure, microhardness, and tube eccentricity were investigated using optical microscopy. The rate- and temperature-dependence of the material was characterized by isothermal uniaxial tension experiments. A biaxial experimental setup, consisting of a 2 kN electromechanical tensile stage and a 1.4 kbar hydraulic pump, was created to internally pressurize and axially load the microtube in biaxial stress states. Fourteen radial nominal stress path tests were conducted to …

Investigation On Epoxy Resin Yielding Under Pure Hydrostatic Stresses And A Novel Method To Reduce Microcracking, Hesam Jafari

Master's Theses and Capstones

Microcracking and failure in the resin pockets of 3D woven composites is caused by coefficient of thermal expansion mismatch between composite components during cooling from the curing temperature. The failure of the matrix is known to be dependent on triaxial stress state. This study presents first measurements of the effect of pure hydrostatic stress on the failure of epoxy resin as a function of temperature. We found that failure triaxial stress for epoxy resin is not strongly temperature dependent. Strategies to reduce or eliminate microcrackings by means of modifications of the curing schedule are also presented. We show that it …