The effects of electron beam radiation on the rheological behavior of a polystyrene/poly(vinyl methyl ether) blend as a function of absorbed dose, composition, and temperature, were investigated. The purpose of this research has been to modify the viscosity of polystyrene by studying the influences of the addition of a small amount of poly(vinyl methyl ether), combined with the exposure of the blends to low radiation doses. It is shown that the crosslinking behavior, in terms of the changes in the viscosity, is more pronounced and significant for the highest PVME content system composed of 10 wt % PVME. The other blends under consideration in this study do not display significant modifications in their rheological response after irradiation. The effects of radiation and composition on the temperature dependence of the viscosity is illustrated using the Arrhenius Law. The results obtained, in terms of flow activation energy, Ea, show that no real changes occurred due to radiation. On the other hand, it is found that the flow activation energy is strongly dependent on the blend composition. The phase separation temperature as a function of radiation dose and composition is also examined. It is shown that the most noticeable change occurs at a radiation dose of 10 Mrads, the phase separation temperature increasing also as PVME content increases in the blend composition. / Master of Science

The extraction of fifteen (15) polymer additives with supercritical carbon dioxide which are used as antioxidants, uv stabilizers, process lubes, flame retardants and antistats from eight formulations of polystyrene is demonstrated and compared to traditional dissolution/precipitation extractions. The purpose of the study was twofold: 1) the development of a high performance liquid chromatography (HPLC) method(s) for the additives and 2) the determination of the viability of supercritical fluid extraction (SFE) for the additives from polystyrene. Separation of some of the additives was achieved using reversed phase liquid chromatography. Nine of the additives were assayed in this manner while, the remaining six additives could not be assayed using reversed phase liquid chromatography. In order to develop an extraction method for the additives, the effects of static extraction time, CO2 density, and temperature were first investigated. These preliminary extractions revealed that a static extraction period which afforded an opportunity for the polymer to swell combined with a high CO2 density and extraction temperature above the glass transition (Tg) yielded quantitative recoveries of the additives. Triplicate extractions of the various polystyrene formulations matched additive recoveries obtained by the traditional dissolution/precipitation method. / Master of Science

The purpose of this study was to evaluate the effect of film thickness on a polystyrene coating used to prevent fretting corrosion in a steel-on-steel system. The polystyrene coating was applied to a 1045 steel disk and fretted against a 52100 steel ball. Two sets of experiments were employed. The first set evaluated film life by using seven different film thicknesses ranging from 7.9 to 52 um. The results from this set of experiments indicated that a drastic increase in film life occurred for coatings thicker than 40 pm. The other set of experiments was used to study how fretting damage progressed with time and how it was affected by film thickness. For this purpose two film thicknesses, 38 and 52 μm, were used. The results from these experiments led to the speculation that stress and temperature conditions were different in the 38 and 52 μm films. These differences resulted in a milder fretting regime, and therefore longer life, in the thicker film. Optical and scanning electron microscopy and computer graphics were used to study in detail the fretting interface. The fretting mechanisms were explained in terms of mechanical, chemical, tribochemical, and tribophysical effects. / Master of Science

The thermal conductivities of polystyrene in benzene solutions at concentrations of 0.l to 15 weight percent were measured at 25° C and atmospheric pressure. Osmotic pressure measurements and information supplied by the manufacturer indicated number average molecular weights (M̅_N) of 21,000, 264,000, and 660,000 for the three polystyrene polymers studied. The following equation was obtained by regression analysis of the results and predicts the measured thermal conductivity within ± 2 percent in the range of variables studied. K = 0.1088 - 0.1311 C + 0.57629 C² - 6.40 x 10⁻⁵ (M̅_N x 10⁻⁵)² - 4.2 x 10⁻³ C(M̅_N x 10⁻⁵) where: K = thermal conductivity of solution, Btu/hr-ft-°F C = weight fraction polymer M̅_N = number average molecular weight The conductivities were measured in a steady-state concentric cylinder apparatus developed for measuring the thermal conductivity of viscous liquids. The annular gap was 0.052 inches and guard heaters were employed to minimize end losses and distortion of the steady-state temperature distribution at the ends. The apparatus was calibrated with three liquids of known thermal conductivity, water, cyclohexanol and ethylene glycol. The calibration factor was found to be constant to within experimental error (± 3 percent) over the range of measurements. / Master of Science

Introduction The degradation of plastic waste into smaller micro- and nanoplastic (MNPs) molecules has led to widespread distribution of these particles and accumulation in the environment, making human exposure inevitable. This can result in, or exacerbate, pathological conditions leading to immune dysfunction, neurodegenerative diseases, and infertility. Yet few studies have examined the effects of nanoplastics (NPs) on human health, especially the reproductive system. Reproductive toxicity of plastic particles has been mostly studied in males with most studies investigating microplastics. Therefore, the present study aims to assess the reproductive health consequences of NPs exposure in females by quantifying serum estradiol and progesterone, examining estrous cyclicity, and assessing ovarian reserve (number and quality of follicles) which is a key indicator of female fertility. Materials & Methods The present study was carried out in female mice (C57BL/6) exposed orally to water (control) or one of two solutions containing different concentrations of Polystyrene nanoplastics (PS-NPs; 100 µg/l or 1000 µg/l in water. Exposure occurred daily for 29 days, and vaginal lavage samples were collected for the last 15 days of the exposure phase to check for change in estrous cyclicity. Mice were euthanized at the end of the study and their blood samples and reproductive tissues were collected. Ovaries were fixed in 10% formalin, embedded in paraffin wax, serially sectioned at 5 µm thickness, and stained with hematoxylin and eosin (H&E) for microscopy and follicle analysis. ELISA was also performed to quantify the progesterone and estradiol serum levels. Results There was a significant increase in the estrous cycle length in the high dose (1000 µg/l) PS-NPs exposure group compared to control (5.53±.25 days vs 4.7±0.23 days, P=0.02). Moreover, there was a significant decrease in serum progesterone levels in the high-dose exposure group compared to control (mean difference=1.64 pg/ml, standard error of difference (SED)=0.64, P=0.03). Additionally, it was shown that PS-NPs exposure significantly reduced antral follicles’ diameter in both the low dose (238.61±19.01 µm vs 167.35±19.01 µm, P=0.03) and high dose exposure groups compared to the control group with the higher dose showing a more pronounced reduction in antral follicle' size (238.61±19.01 µm vs 131.95±19.01 µm, P=0.001). Conclusion Oral PS-NPs exposure in female mice appears to induce toxicity by reducing antral follicles size, increasing the estrous cycle length, and decreasing progesterone levels which may result in anovulation and different reproductive issues, such as infertility and polycystic ovary syndrome (PCOS). The effect of PS-NPs on infertility along with NPs’ mechanism of action in female reproductive system should be investigated in future studies. / Thesis / Master of Science (MSc) / Plastics in the environment break down into smaller particles called micro- and nanoplastics. These plastic particles are pollutants present in the aquatic and terrestrial environments entering every level of the food chain and ultimately reaching humans, yet few studies have examined the effects of nanoplastics on human health. A recent World Health Organization (WHO) report on nanoplastics has stressed the urgent need for toxicological studies to assess potential human health effects. Therefore, this study examined the effect of nanoplastics on the female reproductive system. This study was carried out in female mice exposed orally to a solution containing a vehicle control (water) and two different concentrations of nanoplastics (100 and 1,000 µg/l). Exposure occurred daily for a period of 29 days. At the conclusion of the study the mice were humanly euthanized with their blood and reproductive tissues collected for laboratory analysis. Results showed that nanoplastics exposure resulted in irregular reproductive cycle in mice along with a decrease in antral follicle size and progesterone levels which are indicators of anovulation and can lead to disorders, such as infertility and polycystic ovary syndrome (PCOS) which should be further investigated in future studies.

Abstract Introduction The degradation of plastic waste into smaller micro- and nanoplastic (MNPs) molecules has led to widespread distribution of these particles and accumulation in the environment, making human exposure inevitable. This can result in, or exacerbate, pathological conditions leading to immune dysfunction, neurodegenerative diseases, and infertility. Yet few studies have examined the effects of nanoplastics (NPs) on human health, especially the reproductive system. Reproductive toxicity of plastic particles has been mostly studied in males with most studies investigating microplastics. Therefore, the present study aims to assess the reproductive health consequences of NPs exposure in females by quantifying serum estradiol and progesterone, examining estrous cyclicity, and assessing ovarian reserve (number and quality of follicles) which is a key indicator of female fertility. Materials & Methods The present study was carried out in female mice (C57BL/6) exposed orally to water (control) or one of two solutions containing different concentrations of Polystyrene nanoplastics (PS-NPs; 100 µg/l or 1000 µg/l in water. Exposure occurred daily for 29 days, and vaginal lavage samples were collected for the last 15 days of the exposure phase to check for change in estrous cyclicity. Mice were euthanized at the end of the study and their blood samples and reproductive tissues were collected. Ovaries were fixed in 10% formalin, embedded in paraffin wax, serially sectioned at 5 µm thickness, and stained with hematoxylin and eosin (H&E) for microscopy and follicle analysis. ELISA was also performed to quantify the progesterone and estradiol serum levels. Results There was a significant increase in the estrous cycle length in the high dose (1000 µg/l) PS-NPs exposure group compared to control (5.53±.25 days vs 4.7±0.23 days, P=0.02). Moreover, there was a significant decrease in serum progesterone levels in the high-dose exposure group compared to control (mean difference=1.64 pg/ml, standard error of difference (SED)=0.64, P=0.03). Additionally, it was shown that PS-NPs exposure significantly reduced antral follicles’ diameter in both the low dose (238.61±19.01 µm vs 167.35±19.01 µm, P=0.03) and high dose exposure groups compared to the control group with the higher dose showing a more pronounced reduction in antral follicle' size (238.61±19.01 µm vs 131.95±19.01 µm, P=0.001). Conclusion Oral PS-NPs exposure in female mice appears to induce toxicity by reducing antral follicles size, increasing the estrous cycle length, and decreasing progesterone levels which may result in anovulation and different reproductive issues, such as infertility and polycystic ovary syndrome (PCOS). The effect of PS-NPs on infertility along with NPs’ mechanism of action in female reproductive system should be investigated in future studies. / Thesis / Master of Science (MSc) / Plastics in the environment break down into smaller particles called micro- and nanoplastics. These plastic particles are pollutants present in the aquatic and terrestrial environments entering every level of the food chain and ultimately reaching humans, yet few studies have examined the effects of nanoplastics on human health. A recent World Health Organization (WHO) report on nanoplastics has stressed the urgent need for toxicological studies to assess potential human health effects. Therefore, this study examined the effect of nanoplastics on the female reproductive system. This study was carried out in female mice exposed orally to a solution containing a vehicle control (water) and two different concentrations of nanoplastics (100 and 1,000 µg/l). Exposure occurred daily for a period of 29 days. At the conclusion of the study the mice were humanly euthanized with their blood and reproductive tissues collected for laboratory analysis. Results showed that nanoplastics exposure resulted in irregular reproductive cycle in mice along with a decrease in antral follicle size and progesterone levels which are indicators of anovulation and can lead to disorders, such as infertility and polycystic ovary syndrome (PCOS) which should be further investigated in future studies.

Polystyrene (PS) nanocomposite foams were prepared using supercritical fluid (SCF) CO2 as a solvent and blowing agent. PS was first in-situ polymerized with a range of concentrations of montmorillonite layered silicate (MLS). The polymerized samples were then compression molded into 1 to 2mm thick laminates. The laminates were foamed in a batch supercritical CO2 process at various temperatures and pressures from 60°-85°C and 7.6-12MPa. The resulting foams were analyzed by scanning electron microscopy to determine effect of MLS on cellular morphology. Differential scanning calorimetry was used to determine the impact of nanocomposite microstructure on glass transition of the foamed polymer. X-ray diffraction spectra suggested that the PS/MLS composite had an intercalated structure at both the 1% and 3% mixtures, and that the intercalation may be enhanced by the foaming process.

Lors de ce travail, de fins films de polystyrène ont été déposés dans la post-décharge d’une torche plasma atmosphérique commerciale, mais aussi dans la décharge d’une DBD (Décharge à Barrière Diélectrique), conçue et développée par nos soins au laboratoire. Une DBD est un procédé permettant d’obtenir des plasmas froids à pression atmosphérique. <p><p>Nos résultats ont montré que la DBD permettait d’obtenir des films de polystyrène de meilleure qualité (degré d’oxydation moindre…) qu’avec la torche commerciale en raison de l’atmosphère contrôlée de l’enceinte DBD. Les films sont déposés en présence d’un gaz porteur (Ar ou He dans la DBD). Nous avons pu mettre en évidence l’influence de la nature de ce gaz porteur sur la structure des films (degré de branchement, et de réticulation des films et de préservation des cycles aromatiques de la molécule de départ). <p><p>Les dépôts de polystyrène sulfoné ont été synthétisés dans la DBD en une seule étape, par « copolymérisation » de deux précurseurs (styrène et acide trifluorométhane sulfonique) injectés simultanément dans la décharge. Ces membranes pourraient servir d’électrolyte dans les piles à combustibles miniaturisées de type PEMFC (« Polymer Electrolyte Membrane Fuel Cell »), utilisant de l’hydrogène ou du méthanol et ce pour des applications portables. <p><p>L’acide trifluorométhane sulfonique permet le greffage de groupements sulfoniques échangeurs d’ions (nécessaires pour la conductivité de la membrane) sur le squelette de polystyrène. <p><p>La complémentarité des différentes techniques spectroscopiques utilisées -Spectroscopie des Photoélectrons X (XPS), Infra-Rouge à Transformée de Fourier (FTIR), Spectroscopie des Ions Secondaires (SIMS) statique et dynamique- ont montré que les groupements acides sulfoniques (bien préservés dans la décharge à pression sub-atmosphérique) étaient bien greffés dans la matrice de polystyrène, et ce sur toute l’épaisseur de la membrane. L’influence des paramètres (température de l’acide, tension appliquée entre les électrodes, nature du gaz porteur…) sur la quantité de groupements ionisables greffés, sur la vitesse de dépôt et aussi sur la morphologie des films a été étudiée respectivement par XPS et par microscopie. <p><p>En plus des dépôts sur substrats usuels (Si, acier…) utilisés pour les caractérisations chimiques, nous avons synthétisé les films directement sur des électrodes de carbone enrichies en platine.<p> <p>Nous avons déposé le catalyseur à partir d’une solution colloïdale de platine nébulisée dans la post-décharge d’une torche plasma atmosphérique sur des couches de carbones poreuse et sur du carbone vitreux (utilisé comme modèle pour le profilage par SIMS dynamique) dans différentes configurations et ce pour différents paramètres afin de constituer des électrodes servant de substrat pour l’adhésion de la membrane-plasma pour des perspectives d’assemblage membrane-électrodes pour PAC. /<p><p>\ / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This research was designed to fabricate and characterize novel polyhedral phase segregated microstructures of polystyrene (PS)-matrix composites filled with multi-walled carbon nanotubes (MWNT) and indium tin oxide (ITO) nanopowders. PS-composites were compression molded with MWNT and ITO separately first. The resulting composites were conducting, and remained optically transparent. Mixtures of MWNT and ITO were then used to form mixed ITO/MWNT PS-composites in order to optimize their transparency and conductivity. This was achieved by fabricating composites with varying concentrations of fillers. Impedance spectroscopy was used to characterize the electrical properties of the PS-composites. Optical properties were characterized by measuring the transmission of light through the PS-composite in the visible light spectrum using a spectrophotometer. The electrical properties and microstructural attributes of the fillers used were also characterized. The main objective of the project was to understand the relationships between the structural, electrical, and optical properties of the PS-composites. The resistivity of PS-composites filled with MWNT ranged from 105 to 1013 Ω cm for samples with 0.007 to 0.9 vol% MWNT. The resistivity of PS-composites filled with ITO ranged from 107 to 1013 Ω cm for PS-composites with 0.034 to 0.86 vol% ITO. PS/ITO composites had a percolation threshold of 0.15, 0.25, or 0.3 phr ITO, depending on the type of ITO used in the composite. The percolation threshold of PS/MWNT composites was found to be 0.01 phr MWNT. Mixed ITO/MWNT PS-composites were already percolated, the concentrations investigated in xv ii this study were already above the percolation threshold of these composites. A time dependence on impedance was found for PS-composites filled with MWNT. As time increases there is a decrease in impedance, and in some cases also a dependence on voltage. All PS-composites showed a dependence on the microstructure of the PS matrix and the filler material. The resistivity and percolation threshold were lower for PS/MWNT composites than PS/ITO composites due to the difference in filler size and aspect ratio, since MWNT have a smaller size. The orientation of PS grains with respect to neighboring grains was found to affect the resistivity of PS/MWNT. PS/MWNT composites with preferentially oriented PS grains were found to have a lower resistivity. Mixed ITO/MWNT PS-composites with the right filler concentrations were able to maintain transmission while decreasing resistivity. The fracture surface of fractured PS-composites prepared in this work indicated that there was bonding between adjacent PS-grains. From this work, it can be concluded that large grain hybrid ITO/MWNT PS-composites provide insight into the effect of combining nanometer sized filler materials together in a polymer matrix on the resultant structural, electrical, and optical properties of the composite. In the future, it is recommended that this study be used to aid research in flexible transparent conducting electrodes using a polymer matrix and hybrid/mixed nanometer sized conducting fillers.

Purpose: This project compares two foundation insulation materials: cellular plastic and cellular glass. Currently, cellular plastic is the most used material for foundation insulation. While cellular glass is not widely utilized. Its disadvantage lies in its higher cost, which makes contractors prefer the cheaper alternative, cellular plastic. Cellular glass exhibits exceptional properties, including its notable attributes of high load-bearing capacity and superior moisture resistance. The aim of this study is to demonstrate how material savings can be achieved by using cellular glass instead of cellular plastic in the load-bearing parts of the foundation. In addition to cost savings, the study also includes the analysis of carbon dioxide emissions during the production of these materials and specific heat losses through the material. Method: To facilitate understanding of the study, two different buildings were visualized: a two-story building and a seven-story building. The choice of different building sizes aimed to investigate how different loads on foundation insulation affect insulation material costs, carbon dioxide emissions, and the heating requirements of the buildings. Revit and AutoCAD were used for modelling and visualization. Flixo and manual calculations were employed for energy calculations, while manual calculations were used for structural calculations. One Click LCA Software was used to determine the carbon dioxide emissions for the different foundation insulation scenarios. Results: The study suggests that for buildings with lighter loads, cellular plastic is a cost-effective choice, while a hybrid insulation approach combining cellular glass and cellular plastic is the best option considering environmental factors. However, for buildings with higher loads, cellular glass outperforms cellular plastic both in terms of economics and the environment. Nonetheless, a combination of cellular glass and cellular plastic remains the most favourable choice among the three scenarios, as energy losses are approximately the same due to the similar thermal conductivity values of these materials. Conclusion: Hybrid insulation proves to be the most advantageous option in terms of both the environment and economics for both types of buildings studied: the two-story residential building and the seven-story residential building. By using cellular glass F for the load-bearing structures and cellular plastic EPS S60 for the ground slab, effective insulation is achieved. The use of cellular glass F results in material savings, such as cellular plastic XPS 700, which has half the load-bearing capacity of cellular glass F. Additionally, reducing the use of extra concrete for load-bearing foundation constructions decreases the load on the foundation insulation material.