Developing new membrane morphologies and modifying the existing membrane materials are required to obtain membranes with improved gas separation performances. The incorporation of zeolites and low molecular-weight additives (LMWA) into polymers are investigated as alternatives to modify the permselective properties of polymer membranes. In this study, these two alternatives were applied together to improve the separation performance of a polymeric membrane. The polycarbonate (PC) chain characteristics was altered by incorporating p-nitroaniline (pNA) as a LMWA and the PC membrane morphology was modified by introducing zeolite 4A particles as fillers. For this purpose, pure PC and PC/pNA dense homogenous membranes, and PC/zeolite 4A and PC/pNA/zeolite 4A mixed matrix membranes (MMM) were prepared by solvent-evaporation method using dichloromethane as the solvent. The pNA and zeolite 4A concentrations in the casting solutions were changed between 1-5% (w/w) and 5-30% (w/w), respectively. Membranes were characterized by SEM, DSC, and single gas permeability measurements of N2, H2, O2, CH4 and CO2. They were also tested for their binary gas separation performances with CO2/CH4, CO2/N2 and H2/CH4 mixtures at different feed gas compositions. DSC analysis of the membranes showed that, incorporation of zeolite 4A particles into PC/pNA increased the glass transition temperatures, Tg, but incorporation of them to pure PC had no effect on the Tg, suggesting that pNA was a necessary agent for interaction between zeolite 4A and PC matrix. The ideal selectivities increased in the order of pure PC, PC/zeolite 4A MMMs and PC/pNA/zeolite 4A MMMs despite a loss in the permeabilities with respect to pure PC. A significant improvement was achieved in selectivities when the PC/pNA/zeolite 4A MMMs were prepared with pNA concentrations of 1 % and 2 % (w/w) and with a zeolite loading of 20 % (w/w). The H2/CH4 and CO2/CH4 selectivities of PC/pNA (1%)/zeolite 4A (20%) membrane were 121.3 and 51.8, respectively, which were three times higher than those of pure PC membrane. Binary gas separation performance of the membranes showed that separation selectivities of pure PC and PC/pNA homogenous membranes were nearly the same as the ideal selectivities regardless of the feed gas composition. On the other hand, for PC/zeolite 4A and PC/pNA/zeolite 4A MMMs, the separation selectivities were always lower than the respective ideal selectivities for all binary gas mixtures, and demonstrated a strong feed composition dependency indicating the importance of gas-membrane matrix interactions in MMMs. For CO2/CH4 binary gas mixture, when the CO2 concentration in the feed increased to 50 %, the selectivities decreased from 31.9 to 23.2 and 48.5 to 22.2 for PC/zeolite 4A (20%) and PC/pNA (2%)/zeolite 4A (20%) MMMs, respectively. In conclusion, high performance PC based MMMs were prepared by blending PC with small amounts of pNA and introducing zeolite 4A particles. The prepared membranes showed promising results to separate industrially important gas mixtures depending on the feed gas compositions.

Two main areas are considered in this manuscript. The first describes the synthesis of group 10 metal complexes incorporating the water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) ligand and the second deals with the preparation of Cr(salen)X catalysts for the copolymerization of CO2 and epoxides. In the first topic, the synthesis of nickel(II) and palladium(II) salicylaldiminato complexes incorporating PTA has been achieved employing two preparative routes. Upon reacting the original ethylene polymerization catalyst developed by Grubbs and coworkers (Organometallics, 1998, 17, 3149), (salicylaldiminato)Ni(Ph)PPh3, with PTA using a homogeneous methanol/toluene solvent system resulted in the formation of the PTA analogs in good yields. Alternatively, complexes of this type may be synthesized via a direct approach utilizing (TMEDA)M(CH3)2 (M = Ni, Pd), the corresponding salicylaldimine, and PTA. Polymerization reactions were attempted using the nickel-PTA complexes in a biphasic toluene/water mixture in an effort to initiate ethylene polymerization by trapping the dissociated phosphine ligand in the water layer, thereby, eliminating the need for a phosphine scavenger. Unfortunately, because of the strong binding ability of the small, donating phosphine (PTA) as compared to PPh3, dissociation did not occur at a temperature where the complexes are not subjected to decomposition. Additionally, the unexplored PTA derivative, 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA), prepared by the literature procedure, was fully characterized by NMR and X-ray analysis. DAPTA is found be similar to its parent (PTA) in coordination mode and binding strength, as supported by its representative group 6 and group 10 complexes The second main topic involves the copolymerization of CO2 and epoxides (i.e., cyclohexene oxide (CHO)) for the formation of polycarbonate using Cr(salen)X (X = Br, OPh) catalysts with one equivalent of PR3 as the co-catalyst. The use of these catalysts and cocatalysts results in the most active chromium-based catalytic systems to date. The . hr-1highest activities observed are on the order of 109 mol CHO consumed . mol Cr-1 using PCy3 as the co-catalyst, and is clearly seen in the in situ monitoring of copolymer formation. An advantage of these systems involves the lack of cyclic carbonate production and high CO2 incorporation (>99%) within the polymer.

L‟objectif de cette thèse est de valoriser les polymères styréniques issus des déchets d‟équipements électroniques et électriques. Les polymères considérés sont le polystyrène (PS), le polystyrène choc (HIPS), le poly(acrylonitrile-butadiène-styrène) (ABS), l'ABS couplé avec du polycarbonate (ABS/PC) et le poly(styrène-acrylonitrile) (SAN). Une étude préliminaire a permis de définir deux mélanges à compatibiliser : le mélange PS/ABS et le mélange PS/PC. Pour le mélange PS/ABS, la voie de compatibilisation ionique est étudiée. L‟ajout d‟un copolymère présentant une structure ionique et la création d‟un réseau in-situ sont tentés. Ces deux voies n‟ont pas donné de résultats concluants en termes d‟amélioration des propriétés finales du mélange. Le mélange PS/PC est lui compatibilisé par ajout d‟un copolymère polystyrène bloc-poly(éthylène-butylène)-bloc-polystyrène greffé PC. Ce copolymère est tout d‟abord créé en mélangeur interne, afin d‟étudier différents catalyseurs susceptibles d‟initier le greffage, puis l‟extrusion réactive est utilisée pour synthétiser ce copolymère à grande échelle. Plusieurs taux de copolymère sont alors introduits dans le mélange PS/PC et l‟amélioration des propriétés et des microstructures prouve son effet compatibilisant

The use of dense CO2 in polymer processing can provide a response to the need for more environmentally-friendly industrial processes. Products with high-purity, sterility, and porosity can be achieved using dense gas technology (DGT). Currently, DGT has been used in different aspects of polymer processing including polymerization, micronization, and impregnation. Due to its solubility in polymers, CO2 can penetrate and plasticize polymers, while impregnating them with low-molecular weight CO2 -soluble compounds. Biodegradable polymers and other medical-grade polymers have benefited from the application of DGT. Dense CO2 processing properties of inertness, non-toxicity, and affinity for various therapeutic compounds are specifically advantageous to the medical and biomedical industries. In this work, the different applications of DGT in polymer processing are revised, then implemented. The polymerization of polycarbonate (PC) and polycaprolactone (PCL) in dense CO2 are presented. The syntheses of both polymers were successful and were aided by the use of dense CO2 . A multi-stage approach using dense CO2 as a sweep fluid to extract the PC polymerization by-product phenol is reported. Polycaprolactone was synthesized with varying temperatures and dense CO pressures, then impregnated with a CO2 -soluble therapeutic agent. The impregnated PCL acted as a drug reservoir with a drug-loading of 27wt% and a sustained drug release profile was observed for all samples over several days. Polymer blends of PC/PCL have potential industrial and biomedical applications both in vivo and in vitro. The applicability of PCL can be extended by enhancing its mechanical properties by creating a bio-blend with a stronger polymer such as PC. In this work, PC/PCL nonporous and porous blends were produced. Three novel dense CO2 blending techniques were used. The macroporous PC/PCL blend was impregnated with a therapeutic agent using CO2 as the carrier. A drug loading of 20wt% was achieved and sustained drug release was observed over 3 days. The applicability of dense CO2 in polymer processing was further demonstrated by sterilizing macroporous PC/PCL blends and soft hydrogels with dense CO2 . The PC/PCL blends and hydrogels were inoculated with vegetative bacteria and bacterial endospores. Industrial standard sterilization levels were achieved.

Made available in DSpace on 2016-06-02T20:36:52Z (GMT). No. of bitstreams: 1 6018.pdf: 3012606 bytes, checksum: 9ae3e289d5f93c0bcdb9dc90e59c2bc8 (MD5) Previous issue date: 2014-02-25 / Universidade Federal de Sao Carlos / New alternatives to the use of polymeric membranes as solid electrolyte in fuel cells have been considered , in order to find solutions to recurrent obstacles that limit the performance of these cells, the dependence of the ionic transport due to the water content of the membrane and low thermal stability of the current polymers used . In this investigation, we sought an alternative, by studying the incorporation of imidazolium salts into polycarbonate (PC) matrix and the subsequent formation of membranes via casting. Characterizations that aimed to establish structure-property correlations by FTIR, DSC, TGA, DMTA, Water Vapor Permeation (WVT), Sorption and Desorption and Methanol Permeation were performed. The results indicated that the presence of different ionic liquids (IL) into the PC matrix significantly alter the structural and membrane transport characteristics analyzed. / Novas alternativas ao uso de membranas poliméricas como eletrólito sólido em células a combustível têm sido buscadas, visando encontrar soluções a recorrentes empecilhos que limitam o desempenho dessas células, como a dependência do transporte iônico em função do teor de umidade da membrana e a baixa estabilidade térmica dos atuais polímeros utilizados. Nesta investigação, buscou-se uma alternativa, estudando-se a incorporação de sais de imidazolina em matriz de policarbonato (PC) e a subsequente formação de membranas via casting. Caracterizações que visaram estabelecer correlações estrutura-propriedades foram realizadas através FTIR, DSC, TGA, DMTA, permeação ao vapor de água (WVT), Sorção e Dessorção e Permação ao Metanol. Os resultados indicaram que a presença dos diferentes líquidos iônicos (LI) na matriz de PC altera significativamente as características estruturais e de transporte nas membranas analisadas.

Bisfenol A (BPA) är ett propanderivat med två fenolgrupper. Det syntetiserades för första gången år 1905 av Thomas Zincke vid Marburgs universitet. När en polymerkemist upptäckte att det kunde användas för att bilda polykarbonatplaster växte dess popularitet. Idag är BPA-industrin en miljardindustri och många av oss använder dagligen plaster där denna kemikalie ingår. Nu har det gjorts nya toxikologiska undersökningar som visar att BPA kanske inte är så ofarligt som man tidigare trott. Vårt största intag av föreningen sker via mag-tarmkanalen genom att det kan läcka från olika slags plastföremål i kontakt med livsmedel. Enligt en panel sammansatt av USA:s National Institutes of Health finns det en risk för negativa effekter på hjärna och beteende hos barn. Reaktionerna på riskbedömningarna har varierat och detta examensarbete vill presentera några argument för vikten av att undersöka BPA: s hälsorisker mer. Syftet med detta examensarbete är att med en litteraturstudie undersöka en del av vad som finns dokumenterat om BPA: s hälsorisker för människan, typ av genomförda toxikologiska undersökningar och hur dessa resultat har påverkat företag och länder. Denna litteraturstudie visar att det finns stor bredd på tolkningen av de toxikologiska studiernas resultat och därmed är det osäkert om det finns hälsorisker eller inte. Det finns omdebatterade resultat som tyder på en ökad risk av toxikologiska effekter, till exempel skada på hjärta hos barn men det finns ingen fastställd hälsorisk för människor. Mer standardisering behövs i forskningen för att ge den en högre kvalitet och göra studier mer jämförbara. / Bisphenol-A (BPA) is a propane derivative with two phenol groups. It was synthetisized for the first time in the year of 1905 by Thomas Zincke at the Marburg University. When a polymer chemist discovered that it could be used to form polycarbonate plastics its popularity grew. Today the chemistry of BPA is a billion industry and many of us use daily plastics in which this chemical is used for. Many new toxicological studies have shown that BPA maybe is not as friendly as before thought. Our biggest exposure to it is orally because it can leak from different plastics with contact to food. According to a panel assembled by USA’s National Institutes of Health there is a risk of negative effects on brain and behaviour on children. The reactions of the risk assessment have been different and this thesis wants to show some arguments for the importance of exploring the health risks of BPA more. The purpose of this thesis is to use a literature study to investigate a part of what is documented about the health effects of BPA on humans, the kind of toxicological studies performed and how their results have affected companies and countries. The literature study shows that the width of interpretation of the toxicological studies’ results is big and thus that it is uncertain if there are health effects or not. There are some uncertain results facts funded on conflict that show a heightened risk for toxicological effects, for example damage on heart and changes in behavior in infants but there is no empirically stated health risk in humans. More standardization in research is needed for giving it a higher quality and thus making it more comparable.

Master of Science / Department of Chemical Engineering / Larry E. Erickson / Polycarbonate products have been used extensively world wide for decades because they are lightweight, shatter-resistant and considered to be safe. Polycarbonate is a thermoplastic that is used to make compact discs, phones, lenses, and food contact products such as water bottles, baby bottles and food storage containers. For more than half century, there has been interest in polycarbonate (PC) products and the monomer bisphenol-A (BPA) because BPA can leach from food polycarbonate containers. The environmental fate for both chemicals in air, water and soil is of interest, also. To understand the fate of polycarbonate, its main degradation pathways, main degradation mechanisms and main products are reviewed. These pathways are thermal degradation, photo-degradation and hydrolysis under different conditions. Furthermore, key topics like PC degradation kinetics and PC chemical resistance are part of this comprehensive discussion. The biodegradation of BPA has been thoroughly studied. About twelve lab methods for environmental fate are summarized and reviewed to understand the “big picture” for BPA degradation. This includes screening tests, which assess the ready and inherent degradability, to simulation tests for surface waters, soils and wastewater treatment systems. The testing of all methods is examined under conditions close to the real environment fate. Furthermore, the fate distribution for BPA based on the Equilibrium Criterion Model (EQC) model is reviewed. Extensive research on polycarbonate and BPA has been conducted in the last fifty years. During this time, both chemicals have been studied and tested by industry and government agencies. The pharmacological test results from major studies indicate that consumer exposure to BPA at concentrations normally experienced in daily living does not pose a risk to human health. On the other hand, minor toxicological studies indicate potential risks to human health. Research on health and safety are continuing.

Strong underwater bonds between polycarbonate sheet and various other substrates were achieved using ethyl 2-cyanoacrylate gel cured with an anionic photoinitiator (dibenzoylferrocene). The gel reacts quickly with water on contact and forms a protective polyethyl cyanoacrylate (PECA) skin. This provides a diffusion barrier that protects the inner monomer from further reaction with or polymerisation by water (hydroxide ions). The PECA skin is, however, permeable to water and the inner monomer slowly reacts as water diffuses through the PECA skin. The application procedure for this adhesive is critical because of the fast reaction with water. The adhesive should be applied at the centre of the bond area in such a way as to cover the smallest exposed surface area and that it should not be spread out over the entire surface area. The PECA skin will rupture when the substrates are pressed together, exposing unreacted monomer to the fresh new surface between the two substrates. The adhesive displaces water as it propagates towards the joint edges. In this way it is able to form a strong underwater bond. Without a photoinitiator, ethyl cyanoacrylate adhesives will form strong bonds to smooth underwater surfaces. The addition of a photoinitiator (dibenzoylferrocene), however, increases the rate at which the bond strength develops. Photo differential scanning calorimetric (photo-DSC) analysis was used to determine the optimum photoinitiator concentration. A concentration of between 0.3% (m/m) and 0.1% (m/m) was found to be optimum for adhesive films between 0.5 and 1.2 mm thick. Epoxy-based underwater adhesives have the disadvantage that the cure rate is very slow at low water temperatures. In contrast, the current system features a negative temperature dependence. Therefore, the curing rate is faster at lower water temperatures, making it highly suitable for very cold environmental conditions. The underwater bonding properties of cyanoacrylate adhesive were measured on a wide range of metallic and non-metallic materials. Bond strengths ranged from 1 to 5 MPa respectively. Bond strength (0.2 mm film thickness) develops in a very short time (less than a minute) using a 5 mW/cm2 blue LED light source as trigger for the photo initiator. Water temperatures between 1.5 and 40 °C did not influence the ultimate bond strength achieved following 50 seconds of illumination. The reduction in bond strength due to the ethyl cyanoacrylates reacting with water was measured in artificial sea water and potable water. A 20% reduction in bond strength was found after 10 minutes of water exposure. The underwater bond should therefore be made as soon as possible following exposure to water. Bond ageing studies on both steel and polycarbonate showed an initial decrease in bond strength (during the first 50 hours); thereafter the bond strength stabilises. / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

The influence of two lubricating and cleaning agents and diesel fuel on environmental stress cracking of polyamide reinforced by glass fibers and polycarbonate was studied in this master thesis. Testing of environmental stress cracking was performed by the method of critical bending deformation. Bergen elliptical strain jig was used for testing. The test liquids caused varying levels of environmental stress cracking of amorphous polycarbonate, but they did not cause environmental stress cracking of glass fiber reinforced polyamide. The test method used allows testing the resistance of both materials against environmental stress cracking of any liquid. The results can be used to design products that are expected to be exposed to corrosive liquids. Quantification of the influence of stress free corrosion on the static and impact properties of polycarbonate and glass fiber reinforced polyamide was performed by accelerated test. Specimens were exposed to test liquid and an elevated temperature of 70 °C. The mechanical properties of the tested materials were significantly affected by elevated temperature exposure. The yield strength of the polycarbonate has increased and the toughness has decreased due to physical aging. The tensile strength of glass fiber reinforced polyamide has increased due to a decrease of the moisture content of the material.

No description available.