Quantitative analyses of configurational defects and chain distribution in the semi-crystalline random copolymers have been established in order to understand the structure-property relationship of these polymeric materials. Poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)), Ethylene-vinyl acetate (EVA) and poly(methyl methacrylate-co-nbutyl methacrylate) ((P(MMA-nBMA) copolymers have been studied. Structural analyses of P(VDF-HFP) copolymer is motivated by its application in drug-eluting stent as a coating material. The copolymerization of bulky HFP unit into the VDF chains influences the crystallizable segments of PVDF. These configurational defects can be correlated to the structure evolution as the function of storage time and temperature. Using the spectroscopic techniques such as infrared (IR), Raman and nuclear magnetic resonances (NMR), the configuration and conformation of P(VDF-HFP) copolymers have been analyzed. The thermal fractionation called Successive Self-nucleation/Annealing (SSA) method is adopted in order to investigate the configurational defects on the crystallizable chain sequences of P(VDF-HFP) copolymers. From the results, the configurational defects introduced by HFP units have been correlated to the multiple thermal transitions. In addition, it is interesting to find that the thermal fractionation can induce a different crystalline conformation in P(VDF-HFP) copolymers. Analysis of chain configuration and crystallizable segmental distribution in ethylene-vinyl acetate (EVA) copolymers is motivated by development of hot-melt adhesives composed mainly of EVA-Wax-tackifier multicomponents blend. In this study, the main focus is on understanding co-crystallization between ethylene segments with paraffins. Using the same thermal fractionation technique used for the characterization of P(VDF-HFP) copolymers, EVA copolymers are also studied. Due to the wide distribution of ethylene segments in EVA, it is expected that the n-alkanes of matching length can cocrystallize with EVA. The presence of co-crystallization is observed by the enhancement in crystallization and faster crystallization kinetics in the binary blends. It has been determined by Infrared spectroscopy by observing changes in the crystalline form and intermolecular interaction in the crystalline unit cell. From the results, the mechanism of co-crystallization has been proposed. Influence of copolymer configuration on the crystallization and phase behavior of ternary blends is also of great interest in order to develop polyurethane-based hot melt adhesives. The phase behavior of various ternary polymer blends containing crystallizable polyester, a non-crystallizable polyether, and an acrylic random copolymer of different chain configuration is investigated. The mean-field Flory-Huggins theory for the free energy of mixing, extended to ternary polymer blends, is adopted for predicting phase diagrams. The differences observed in the rheological processes of various ternary blends with different acrylic copolymers are directly related to changes in miscibility, associated phase behavior and chain configuration.

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Rheology modifiers are used in paints and coatings to ease their application to a surface, prevent sagging once applied, and allow the leveling of brushstrokes, among other benefits. The early rheology modifiers were hydroxyethyl celluloses (HECs), a type of non-associative thickener that is relatively inexpensive and synthesized from cellulose, which is abundant. However, coatings that are modified with HECs tend to suffer from poor leveling and syneresis (phase separation). HECs have since been replaced with associative thickeners (ATs). These thickeners, when properly formulated, produce stable dispersions that have improved rheological properties, yet, unlike HECs, are sensitive to changes to the coating formulation. This drawback has encouraged research that attempts to predict the phase behavior and rheology of systems that are modified with ATs. This work is concerned with the phase behavior and rheology of waterborne latex / hydrophobically-modified ethoxylated urethane (HEUR) AT systems. When latex volume fraction is held constant, the amount of HEUR (and surfactant) in the mixture determines whether the system experiences syneresis. Dispersion phase diagrams (DPDs) of such systems have been previously studied, but the rheology of the mixtures used to prepare the DPDs have not been studied in any detail. A study on the rheology of phase separated latex / HEUR mixtures that were prepared with commercial materials was done at Cal Poly and showed a correlation between syneresis and complex rheology. However, a proper analysis was limited because the compositions and chemical structures of the commercial materials were not well known. To better understand the relationships between phase behavior and rheology, waterborne latex / HEUR mixtures were prepared from latex and HEURs that were made at Cal Poly. Three series of mixtures were studied: commercial latex / commercial HEUR (I), commercial latex / Cal Poly HEUR (II), and Cal Poly latex / Cal Poly HEUR (III). The latex volume fraction was held constant at 0.25 and the concentration of HEUR was varied from 0–2.0 wt%. Mixtures were allowed to equilibrate for 7 days, syneresis was measured on day 7, and steady-state viscosities over a shear rate range of 0.01–1000 s-1 were determined on days 7–9 with a DHR-2 rheometer (TA Instruments) that was outfitted with 40 mm, 2o cone. The mixtures were also studied by microscopy and dynamic oscillatory testing. The chemical structures of the Cal Poly HEURs were determined by proton nuclear magnetic resonance spectroscopy (1H NMR) and the molecular weight by gel permeation chromatography (GPC). From this study, a correlation between syneresis and complex rheology was observed in I. Similar trends were observed in phase-separated II and dispersed (not phase-separated) III, though II with over 0.4 wt% HEUR were ejected from the cone / plate geometry at 1–100 s-1 and III did not demonstrate syneresis. Further investigation of dispersed II and phase-separated III is recommended to confirm the presence of the syneresis–rheology correlation of I in both II and III. In addition to these trends, only 2.1–4.2 wt% II were able to be analyzed by the single-mode Maxwell model. Also the transition from phase-separated to stable dispersion was observed with a polarized microscopy at 5x magnification. In conclusion this study represents progress in the ongoing study at Cal Poly to better understanding the mechanisms behind the syneresis and rheology of these latex / HEUR AT dispersions.

Corrosion is a prevalent concern throughout the world, causing significant monetary and safety concerns. Research has been dedicated to developing cost-effective solutions for corrosion that will also meet increasingly stringent environmental regulations. The recently discovered nanomaterial graphene has been proposed as a potential component in anticorrosion technology due to its strong air and water barrier properties. However, graphene is a relatively expensive, difficult to synthesize material. By incorporating it into nanocomposites, its properties can be exploited even at low concentrations. Previous work has been conducted involving the preparation of anticorrosive polystyrene-graphene nanocomposites; these materials were found to be effective long-term barriers for corrosion. Although the polystyrene-graphene nanocomposites were effective in impeding corrosion on metal substrates, their ease of application left some room to be desired. Painting a substrate is currently the most commonly used method for corrosion prevention, but polystyrene is not typically used in paints due to its incompatible properties with these formulations. If somehow anticorrosive nanocomposites could be incorporated into coatings, the ease of application could be greatly improved. Polyurethanes are commonly used as binders for coatings, so the fabrication and characterization of polyurethane-graphene nanocomposites for use in anticorrosive coatings was chosen as the premise for this project. A number of different physical and chemical nanocomposites were prepared using lab-synthesized graphene and graphene oxide, as well as commercial graphene. Both two component waterborne and solventborne polyurethanes were employed, and nanocomposites were prepared by both physical and chemical methods. The nanocomposites were coated on cold-rolled steel panels and subjected to salt spray testing in conjunction with control panels in order to analyze their anticorrosive properties. Nanocomposite films were also characterized to determine how their thermal and mechanical performance compared to control coatings. Despite promising studies that supported the anticorrosive capabilities of graphene, this project found that graphene may not be ready for integration into viable coatings systems. Its complex structure and properties made uniform dispersion throughout polyurethane seemingly unachievable, no matter how many different formulations were attempted. To prepare well-dispersed polyurethane-graphene nanocomposite coatings, new components would definitely be required to prevent aggregation of graphene. These components may already be commercially available, but most likely would have to be developed specifically for these formulations. Without these components, the anticorrosive properties of polyurethane-graphene nanocomposites cannot be accurately studied.

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UV curing is using UV light as the energy source to induce the polymerization of liquid monomers and oligomers to form a solid polymer. Because UV polymerization is fast and energy-saving and a UV curable system has no VOC (volatile organic compound), this new technology has developed rapidly from thin film applications to thick sample applications. In addition, since the UV cure process can be controlled spatially and temporally, it also has an important application to make gradient materials with locally optimized properties. However, most research on UV cure is based on thin film applications, and the cure kinetics of thick samples are more complex and not well understood.;In this study, we focus on the UV cure kinetics of CD540 (ethoxylated (4) Bisphenol-A dimethacrylate) thin and thick samples (2-8 mm). A photo-bleaching initiator, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure 819), is used in the system. UV cure kinetics are complex, especially when the sample is thick, since the light intensity is a function of depth and also a function of exposure time. In order to understand the complex cure kinetics of thick samples, we first studied the variation in the transmitted intensity and initiator concentration through the depth in thick samples. Based on the experimental measured transmitted intensity, a Matlab program was written to predict the intensity versus depth and exposure time of a thick sample. Then, the UV cure kinetics of thin samples (0.05 mm) were studied. In this part, we studied the effect of light intensity, initiator concentration, and temperature on the cure kinetics experimentally and theoretically. A model was developed based on a unimolecular termination mechanism in order to predict the cure kinetics at different conditions for thin samples. Combining the Matlab program for calculating the intensity in thick samples and the model for calculating the cure kinetics of thin samples, the cure kinetics through the depth of thick samples were predicted and compared with experimental results measured by frequency dependent dielectric sensing.;The diffusion of free radicals in a UV cure free radical cure system was studied by monitoring the cure in the dark nonirradiated region under a mask. In addition, a free radical thermal cure of an acrylic resin was characterized in order to study oxygen diffusion from the surface layers into deeper layers.

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