The objective of this research work was to understand the molecular mechanism of gas transport through amorphous glassy polymers. Especially, emphasis was placed on determining whether or not gas transport in amorphous glassy polymers is directly correlated with the free volume content. Free volume arguments are indeed commonly used to explain the gas transport process. The gas transport properties of bisphenol-A polycarbonate films were examined as a function of the cooling rate, physical aging, and orientation. Such conditions affect the free volume content and its size and shape distribution. Results obtained from permeation experiments were accompanied with dynamic mechanical and density measurements. The experimental results suggest that the diffusion coefficient of small gas molecules in glassy polycarbonate is influenced by the local dynamics or mobility of the polymer chains rather than by the overall free volume content. Indeed, the diffusion coefficient of nitrogen for instance was reduced in fast-cooled samples, despite of the fact that those samples possessed a greater overall free volume content. Fast cooling rates may generate highly restricted conformations which hinder local motions, and therefore tend to increase the activation energy of diffusion. As expected, the greater the free volume content, the greater was the solubility coefficient. The increase in the polymer relaxation times with aging time is believed to restrict the local chain motions, leading to enhanced activation energies of diffusion, and therefore to reduced diffusion coefficients. The change in the solubility coefficients with physical aging revealed that the aging process might not affect all the cavity sizes in polycarbonate equally. According to free volume arguments, one would anticipate that the physical aging of fast-cooled samples (which possess more free volume) should be enhanced compared to that of slowly-cooled samples. Quite interestingly, the decrease in the diffusion coefficient with aging was found to occur much slower in fast-cooled samples, despite of the higher initial free volume content. In contrast, properties directly related to the free volume content, such as density or isothermal DMTA measurements actually showed a greater aging rate in the sample containing the greatest amount of free volume. Slow-cooled samples that are in a low energy conformational state may loose their internal degrees of freedom more rapidly, due to the closer interchain packing and the possibly restricted segmental motions. Studies dealing with orientation and gas transport were complicated by several factors. For instance the fact that the permeation experiments were performed perpendicularly to the orientation of the chains and not along the orientation axis limited the sensitivity of the gas transport properties to orientation. This work points out that dynamic rather than static models should be developed to predict the gas transport phenomenon. / Ph. D.

This thesis presents the characterization of the optical and mechanical properties of silica nanoparticle films fabricated by ionic self-assembly, also known as layer-by-layer (LbL) deposition. Utilizing electrostatic attraction of oppositely-charged materials permits uniform and rapid growth of the constituents onto planar and curved surfaces. In this work, silica nanoparticles are adsorbed onto glass and polycarbonate substrates, as well as micron-scale glass fibers, with the purpose of improving the optical quality of the respective media. Several methods are presented to improve the adhesion and cohesion of silica nanoparticle films on glass substrates. In the first method, the substrate and nanoparticle surfaces are coated with materials containing sulfonate end groups. Next, a photo-reactive polycation known as diazo-resin (DAR) is used in ISAM deposition with the modified silica nanoparticles. Subsequent exposure to UV converts the ionic bonds between the DAR and sulfonate groups into covalent ones. The second method to improve the mechanical strength is to heat the ISAM silica nanoparticle film at a high enough temperature (500 °C) to remove the polymer and partially fuse the nanoparticles. This technique is known as calcination and is shown to significantly improve the mechanical robustness of the film without compromising the optical properties. The final method involves the deposition of precursor and capping polymer layers around bulk silica nanoparticle films with both bilayer and quadlayer designs. The addition of these polymer layers improves the surface contact between adjacent nanoparticles but reduces the film porosity and consequently the optical transparency. Currently the calcination technique is the only one that significantly improves the film adhesion and cohesion, but suggestions are offered to potentially improve the performance of films made by the other two methods. An alternative way to functionalize polycarbonate substrates for silica nanoparticle ISAM deposition is also presented. The molecular structure of polycarbonate at the surface can be modified by exposing it to deep UV (λ = 185, 254 nm). By doing so, the surface becomes populated with carboxylate species, and thus permits ISAM deposition of poly(allylamine hydrochloride) (PAH) and silica nanoparticles. A variety of spectroscopic methods show that the molecular structure is changed by this procedure, and SEM shows that UV treatment improves the uniformity of ISAM films on polycarbonate. Finally, PAH/silica nanoparticle ISAM films are deposited onto glass fibers. The fibers are used for mechanical reinforcement of polymer composite optical media. The role of the nanoparticle film on the fibers is to reduce light scattering at the interfaces of materials with different thermo-optic coefficients, in other words, transmittance losses associated with changes in temperature. Fiber bundles coated with silica nanoparticles suffer from unacceptable levels of aggregation, and hence do not currently improve the transmittance over the temperature spectrum. Some evidence is presented, however, to suggest that the transparency can be improved if fiber aggregation during ISAM deposition can be avoided. / Ph. D.

L’auto-assemblage de copolymères à blocs amphiphiles est un outil puissant de la chimie supramoléculaire pour la conception de nano-objets complexes et fonctionnels. Dans ces travaux de thèse, l’étude approfondie d’un copolymère à blocs « hybride » synthétique-b-peptidique poly(triméthylène carbonate)-b-poly(acide glutamique) pour des applications de vectorisation a été menée. Des morphologies vésiculaires, obtenues par auto-assemblage en voie « co-solvant » et présentant une grande stabilité ainsi qu’un caractère stimulable ont été mises en évidence. Une transition inédite en température, par des phénomènes de fusion et de fission, a pu être observée. L’encapsulation dans ces vésicules polymères d’un principe actif anti-tumoral et de nanoparticules magnétiques, à des taux très élevés, permet d’améliorer le contraste en IRM ainsi que de moduler la libération de la molécule par une variation des paramètres environnementaux (pH, T) ou par un effet d’hyperthermie magnétique. / Block copolymer self-assembly is a powerful tool within supramolecular chemistry to design smart and functional nano-objects. In this thesis work, comprehensive study of hybrid poly(trimethylene carbonate)-b-poly(glutamic acid) block copolymers for drug delivery applications has been conducted. Highly stable vesicular morphologies presenting stimuli-responsive behaviour were prepared using a solvent-injection method. In particular, original temperature responsiveness mediated by fusion and fission events has been evidenced. Dual loading of an anticancer drug and superparamagnetic nanoparticles in these vesicles, at very high loading contents, allows enhancing MRI contrast and controlling drug release kinetics by varying environmental conditions (pH, T) or by using a magnetic hyperthermia effect.

Le sujet concerne l’influence des effets tridimensionnelles sur les champs de déformation et de contrainte au voisinage d’une éprouvette chargée en mode I. La loi de comportement caractéristique des polymères amorphes avec un seuil d’écoulement viscoplastique suivi d’un adoucissement et d’un durcissement à mesure que la déformation augmente est prise en compte. La loi est implantée dans une UMAT abaqus. Les champs au voisinage de l’entaille sont analysés et les résultats 3D comparés à ceux correspondant à un calcul 2D sous l’hypothèse de déformation plane. L’influence de l’épaisseur de l’échantillon est étudiée et nous montrons qu’au-delà d’un rapport épaisseur t sur rayon d’entaille rt, t/rt>20, les champs de déformation plastique sont qualitativement similaires entre les calculs 3D et 2D. En revanche, nous montrons que la répartition des contraintes et notamment celle de la contrainte moyenne est sur-estimée avec un calcul 2D en comparaison à une simulation 3D. Nous prenons en compte par la suite la rupture par craquelage, modélisée avec un modèle cohésif. Une étude paramétrique est menée afin de définir une procédure d’identification des paramètres caractéristiques du modèle cohésif. Par ailleurs les simulations montrent qu’au-delà d’un rapport t/rt supérieur à 20, une ténacité minimum peut être estimée : ceci constitue un résultat important pour la détermination expérimentale de la ténacité des polymères ductiles. / We investigate 3D effect of crack tip palsticity and the influence of the thickness on 3D glassy polymer fracture. The characteristuc constitutive law with a viscoplastic yield stress followed by softening and progressive hardening is accoutne for and implemented in a UMAt routine, in abaqus. The crack tip fields are investigated and 2D plasne strain versus 3D calculations compared. Qualitatively, the palstic distribution are comparableas soon as the ratio thickness over crack tip radius is larger than 20. However, the 2D calculations over estimate the stress distribution compared to the 3D cases. We have accounted for failure by crazing that is described with a cohesive models. A parametric study sheds light on the methodology to use for the calibration of the cohesive parameters. The simulations show that for a ratio thickness over craci tip radius larger than 20, a minimum tuoghness can be observed. This results has implication on the definition of a thickness larger enough experimentally.

Les Déchets d'Equipement Electriques et Electroniques (DEEE) constituent un volume important de déchets dont le constituant majoritaire est l’ABS. C’est pour cela que nous avons travaillé principalement avec des polymères provenant d’un gisement réel (carters d’ordinateurs). Puis, des mélanges ABS/PC ont été élaborés (le PC étant un des constituants d’un gisement de carters), dans le but d’obtenir un matériau avec une résilience au moins équivalente à celle d’un ABS neuf. Même si l’ABS a montré une bonne aptitude à être recyclé seul, après vieillissement et recyclage, sa résilience connaît une chute due à la dégradation de la phase élastomère et à la présence d’ignifugeants. Il est important pour le recyclage de l’ABS et de ses mélanges de séparer les polymères ignifugés de ceux qui ne le sont pas. La voie mélange pour le recyclage de l’ABS par l’ajout de PC a l’avantage de simplifier le tri et de recycler un maximum des polymères présents dans les DEEE. Nous avons tout d’abord réalisé des mélanges ABS/PC neufs pour bénéficier d’une mise en œuvre et d’une composition optimales. L’influence des paramètres du procédé de recyclage (température et vis d’extrusion) et des propriétés des matériaux (taux et viscosité du PC, retardateurs de flamme de l’ABS) sur les propriétés du mélange a été étudiée. Nous avons effectué essentiellement des essais de résistance au choc Charpy et des études morphologiques. Les résultats ont montré qu’une morphologie fibrillaire ou co-continue est favorable à la meilleure résilience des mélanges ABS/PC. Nous avons obtenu pour des mélanges neufs ABS neuf FR/PC neuf réalisés avec 70% d’ABS une résilience supérieure à celle de l’ABS neuf. Mais, à composition égale, ce résultat n’a pas été atteint pour les mélanges majoritaires en ABS recyclé. Souhaitant réaliser des mélanges performants majoritaires en ABS recyclé, la compatibilisation semble nécessaire. Un mélange recyclé majoritaire en ABS, compatibilisé avec du PP-g-MA, est montré plus résilient que l’ABS neuf seul. Toutefois, les compatibilisants ont une efficacité limitée lorsqu’ils sont en présence de retardateurs de flamme ou soumis à un temps de séjour élevé dans la presse à injecter. Nous avons voulu utiliser des nanocharges minérales (montmorillonites), ajoutées en faible quantité, en tant qu'ignifugeants et compatibilisants. Elles se sont avérées inefficaces dans les études préliminaires réalisées. Le choix des nanoargiles minérales doit être optimisé. / WEEE constitute a huge waste volume in which ABS is the major component. So, we focused on polymers from a real deposit (casing of computers); such a deposit contains ABS, PC, PS, ABS-PC. In a first step, recycling of aged ABS was studied. The decrease in the C=C content induces an impact strength drop. Nevertheless, ABS proved to be recyclable given that optimized processing conditions are found. The role of flame retardants was shown to be crucial on the recyclability. Separating polymers with or without flame retardants is the key point of the ABS recycling. However, recycled aged ABS do not recover the impact strength of neat virgin ABS. Then, ABS/PC blends were elaborated in order to obtain a material with an impact strength at least equivalent to the neat ABS. The use of ABS/PC blends for this recycling facilitates the sorting and the utilization of most of WEEE polymers. We first made ABS/PC blends from virgin polymers to have optimal processability and composition. Performing Charpy impact strength tests and morphological studies allowed to evaluate the influence of recycling process parameters (temperature and screw extrusion) and material properties (rate and viscosity of PC and ABS flame retardants). Experimental results indicate that the impact strength of the ABS/PC blends is higher when the morphology is fibrillar or co-continuous. We obtained ABS virgin FR/PC virgin blends (70/30) with an impact strength greater than the neat ABS. But, with equal composition, this result was not reached for the blends. So to achieve reliable blends rich in recycled ABS, compatibilisation is necessary. Recycled ABS/PC blends compatibilised with PP-g-MA is more resilient than the ABS. However, the compatibilising agents have a limited efficiency when they are used in the presence of flame retardants or subjected to a high residence time. Finally, nanoclays were attemptively used as both FR and compatibiliser. Tough they proved uneffective in the very first experiments carried out (the choice of clay need to be optimized).

Large-scale laminated safety glass is increasingly used in the public and private sector for example museums, jewelers or villas. Special safety is provided by these glasses in layered combination with polycarbonate sheets. Due to the low weight and its high tensile elongation comparing glass of the same thickness, highly transparent polycarbonate is suitable for safety-relevant components. Because of the dimensional limitation in the extrusion process, joining polycarbonate compounds are necessary for large-area joint of this laminated safety glass. According to the present state of the art, a transparent weld joint of polycarbonate is not possible. Within the scope of the project, polycarbonate joints were produced by infrared welding and adhesive bonding. The transparency of the joints was realized by varying the process parameters, for example the heating time. Additionally the present study focusses on a new innovative light intensity measurement, because conventional optical test methods can only subjectively assess the transparency and quality of the compound and the welding seam. The principle is based on the transmission of the welded and polished polycarbonate sample by means of a laser and the measurement of the current at the connected photoelectric cell, which is proportional to the intensity of the laserlight. This enables a qualitative evaluation of the joining dimension and -quality such as structural changes over the entire sample width. The results of this objective method correlate with the width of the stress distribution around the joining level, which are made visible with the photoelasticity using a polariscope and thus contribute to a better process understanding.

The work of my MFA thesis exhibition comes directly out of the physical processes that constitute my studio practice. It is work that embodies the labour of my hands and the decisions that guided them in their struggle with unfamiliar materials. Drawing inspiration from subjects as diverse as physics and fiction to create a sculptural arrangement, the work is intended to engage with its audience in an active way through acoustic appropriation and physical presence. As an artist, I set up an environment to be explored, establishing boundaries and also possibilities.

The objective of this work is to determine the effect of four process variables on the properties of blends composed of bisphenol-A polycarbonate (PC) and poly (butylene terephthalate) (PBT) polymers which are compounded using a large scale commercial extruder. The four variables studied are blend composition, specific energy consumption, residence time and shear rate. The last three factors were varied using the extruder screw speed and feed rate. The PC/PBT blends, commercially known as XENOY, were compounded using a WP ZSK 58 mm co-rotating twin screw extruder at the facility of SABIC Innovative Plastics in Cobourg Ontario. The extruder was instrumented to measure online the die pressure, specific energy consumption and blend temperature. The blends were characterized using differential scanning calorimetry, (DSC), scanning electron microscopy, (SEM), gel permeation chromatography, (GPC), and melt volume flow rate, (MVR). After processing, the blend properties determined were melting temperature, glass transition temperature, crystallinity, amorphous phase weight fraction, amorphous phase composition, phase morphology, PBT-rich-phase size, blend molecular weight distribution, and MVR. Using principles available in the literature, a linear regression model was developed to relate the process variables with the online measured properties and output blend properties. Fitting this model allowed the relative importance of each process variable to be estimated for each property. An attempt was also made to identify the general type of PC/PBT blend studied and how it compares with published PC/PBT blend data. It was found that the blends studied were well stabilized since there was no evidence of significant co-polymer formation during processing. Small decreases in molecular weight were attributed to mechanical degradation. Blending increased the crystallization and melting temperatures, as well as blend crystallinity. No practically significant difference in melting temperatures was observed between the different processing conditions. Analysis of glass transitions indicated that the blend components were partially miscible. The amorphous phase compositions were unaffected by blend composition or processing; however, the weight fraction PC-rich-phase present in the blend was strongly influenced by the screw speed. The phase structure of as-extruded blends could not be resolved using the SEM. Therefore, the blends were annealed to coarsen the phases. After annealing, a continuous PC-rich-phase and a discrete PBT-rich-phase were observed. The PBT phase size increased with increasing PBT content. No other statistically significant effects on phase size were observed but this is not conclusive due to the large scatter in the measurements. MVR was primarily influenced by blend composition and specific energy consumption, with the effects of composition being dominant. Further study using higher imaging resolution is required if the phase structures of as received blend pellets are to be characterized. Contrary to current practice, it is recommended that the Utracki-Jukes equation be used rather than the Fox equation for determining amorphous phase composition from glass transition data in PC/PBT blends.

The work of my MFA thesis exhibition comes directly out of the physical processes that constitute my studio practice. It is work that embodies the labour of my hands and the decisions that guided them in their struggle with unfamiliar materials. Drawing inspiration from subjects as diverse as physics and fiction to create a sculptural arrangement, the work is intended to engage with its audience in an active way through acoustic appropriation and physical presence. As an artist, I set up an environment to be explored, establishing boundaries and also possibilities.

The objective of this work is to determine the effect of four process variables on the properties of blends composed of bisphenol-A polycarbonate (PC) and poly (butylene terephthalate) (PBT) polymers which are compounded using a large scale commercial extruder. The four variables studied are blend composition, specific energy consumption, residence time and shear rate. The last three factors were varied using the extruder screw speed and feed rate. The PC/PBT blends, commercially known as XENOY, were compounded using a WP ZSK 58 mm co-rotating twin screw extruder at the facility of SABIC Innovative Plastics in Cobourg Ontario. The extruder was instrumented to measure online the die pressure, specific energy consumption and blend temperature. The blends were characterized using differential scanning calorimetry, (DSC), scanning electron microscopy, (SEM), gel permeation chromatography, (GPC), and melt volume flow rate, (MVR). After processing, the blend properties determined were melting temperature, glass transition temperature, crystallinity, amorphous phase weight fraction, amorphous phase composition, phase morphology, PBT-rich-phase size, blend molecular weight distribution, and MVR. Using principles available in the literature, a linear regression model was developed to relate the process variables with the online measured properties and output blend properties. Fitting this model allowed the relative importance of each process variable to be estimated for each property. An attempt was also made to identify the general type of PC/PBT blend studied and how it compares with published PC/PBT blend data. It was found that the blends studied were well stabilized since there was no evidence of significant co-polymer formation during processing. Small decreases in molecular weight were attributed to mechanical degradation. Blending increased the crystallization and melting temperatures, as well as blend crystallinity. No practically significant difference in melting temperatures was observed between the different processing conditions. Analysis of glass transitions indicated that the blend components were partially miscible. The amorphous phase compositions were unaffected by blend composition or processing; however, the weight fraction PC-rich-phase present in the blend was strongly influenced by the screw speed. The phase structure of as-extruded blends could not be resolved using the SEM. Therefore, the blends were annealed to coarsen the phases. After annealing, a continuous PC-rich-phase and a discrete PBT-rich-phase were observed. The PBT phase size increased with increasing PBT content. No other statistically significant effects on phase size were observed but this is not conclusive due to the large scatter in the measurements. MVR was primarily influenced by blend composition and specific energy consumption, with the effects of composition being dominant. Further study using higher imaging resolution is required if the phase structures of as received blend pellets are to be characterized. Contrary to current practice, it is recommended that the Utracki-Jukes equation be used rather than the Fox equation for determining amorphous phase composition from glass transition data in PC/PBT blends.