Yes / The “sliding graft copolymer” (SGC), in which many linear poly-ε-caprolactone (PCL) side chains are bound to cyclodextrin rings of a polyrotaxane (PR), was prepared and employed to toughen brittle polylactide (PLA) with methylene diphenyl diisocyanate (MDI) by reactive blending. The SGC was in situ crosslinked and therefore transformed from a crystallized plastic into a totally amorphous elastomer during reactive blending. Meanwhile, PLA-co-SGC copolymer was formed at interface to greatly improve the compatibility between PLA and SGC, and the chain extension of PLA also occurred, were confirmed by FTIR, GPC, SEM, and TEM. The resulting PLA/SGC/MDI blends displayed super impact toughness, elongation at break and nice biocompatibility. It was inferred from these results the crosslinked SGC (c-SGC) elastomeric particles with sliding crosslinking points performed as stress concentrators and absorbed considerable energy under impact and tension process. / This work was supported by the National Natural Science Foundation of China (50933001, 51221002 and 51320105012).

Plastics have changed the world of materials due to their high durability, low price, low density, and ease of processing. Unfortunately, the majority of plastic goods produced are discarded instead of recycled, leading to a massive accumulation of plastic waste in landfills and natural habitats. To decrease the impact of plastic waste, sustainable materials and synthetic methods are needed. This dissertation focuses on new strategies for developing renewable and degradable polymers with minimal energy input as well as new methods to blend legacy polyolefins with renewable polymers. The first half of the dissertation focuses on synthesizing polymers using light while the second section focuses on combining traditional polyolefins with renewable polymers. Photo-mediated polymerizations are an attractive alternative to traditional thermal polymerizations due to their ease of setup and the spatiotemporal control afforded by light. Using LED lights also affords a synthetic technique that requires little energy input, thus decreasing the overall environmental impact of the material. In this work, coupling LEDs with a trithiocarbonate allowed for the synthesis of many different polymers and topologies. Bottlebrush polymers synthesized with light afforded molar masses in excess of 11 million Da without the oligomerization of the bottlebrush polymers. These bottlebrush polymers were then used to make reversibly crosslinkable adhesives, allowing for a new example of recyclable adhesives. The second half of the dissertation focuses on developing sustainable polymers using ring-opening metathesis polymerization (ROMP) to combine the properties of polyolefins with renewable polymers. First, polyketones synthesized by ROMP were developed for their potential use as photodegradable polymers. This initial study probed the synthesis of different polyketone monomers and the properties of their respective polymers. Next, a photodegradable and biodegradable thermoplastic elastomer (TPE) was synthesized that incorporated a ketone containing polybutadiene (PB) flanked by polylactide (PLA). The thermomechanical properties were controlled based on the relative length of each block while the rate of photodegradation was controlled by the mol% of ketone incorporated into the PB block. Finally, ABA triblock copolymers of cellulose derivatives and polyolefins were developed for their uses as compatibilizers for blends. With the addition of as little as 1 wt% of the ABA triblock copolymer, the respective blends showed large imp / PHD

No description available.

Various commodity plastics used today are based on fossil fuels. Most of these plastics are non-biodegradable and will persist in the environment over a long time. The bioplastics from renewable resources have the potential to support a greener economy. The two of such renewably resourced bioplastics are poly (hydroxyl butyrate-co-valerate), PHBV and poly (butylene succinate), PBS. We have used petro-based PBS in our study, but renewable resource based PBS is expected to be available on a commercial scale in a very near future. These two bioplastics are both biodegradable. These two bioplastics are both biodegradable. In our study we have used PBS from petroleum resource but PHBV is a brittle bioplastic with a high modulus value and a low elongation at break while PBS is a low modulus bioplastic with a high elongation at break. Complementary properties can be obtained by blending PHBV and PBS. The direct melt blends showed poor mechanical properties due to limited interaction between PHBV and PBS phases. This research focuses on increasing the interaction between PHBV and PBS blends by using compatibilizers. The compatibilizers used in this thesis were dicumyl peroxide, DCP and trimethylolpropane triacrylate, TMPTA. Use of an in situ compatibilization method was done for the melt mixing of PHBV and PBS yielding blends with improved characteristics. The investigations were performed at three different ratios of PHBV and PBS blends. The increase in the compatibility between the two phases was demonstrated through various thermal, thermo-mechanical, rheological and morphological means. The increase in elongation at break was used as a primary marker for compatibilization. The optimization of DCP and TMPTA was carried out, which showed the enhanced interaction between PHBV and PBS phases, with the successful stress transfer from PHBV phase to the PBS phase resulting in increase in elongation at break. Inward shifts in tan delta peak on addition of DCP and TMPTA to the blends also showed increase in compatibility between the two phases. The interfacial adhesion between a brittle and ductile polymer, PHBV and PBS respectively was increased by using DCP and TMPTA. This opened gateways to various novel applications of PHBV and PBS blends via in situ reactive extrusion process. / The Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA) for their financial support via New directions research program (SR9235). We would also like to thank Canadian Foundation for Innovation (CFI) and Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA) for their equipment supports.

L’acide polylactique (PLA) est l’un des polymères biosourcés qui suscite le plus d’intérêt, mais ses propriétés thermomécaniques nécessitent d’être améliorées. Pour ce faire, les méthodes les plus utilisées et étudiées sont de le mélanger avec d’autres polymères ou bien d’y ajouter des charges minérales nanométriques (nanoparticules), afin de constituer un nanocomposite à matrice PLA. C’est dans la combinaison de ces deux approches que s’inscrivent ces travaux de thèse, consacrés à l’élaboration et à la caractérisation des propriétés de nanocomposites à base d’un alliage de PLA et de polyamide 11 (PA11) 80/20 m/m. L’objectif de cette thèse est l’obtention d’un matériau biosourcé aux propriétés thermiques, mécaniques et de réaction au feu améliorées par le contrôle de sa morphologie et l’ajout de nanoparticules et de retardateurs de flamme (RF). Pour y parvenir, deux techniques de compatibilisation, destinées à améliorer l’adhésion interfaciale entre le PLA et le PA11, ont été évaluées. La première consistait à incorporer des nanoparticules de silice. Il a été noté d’importantes modifications de la morphologie et des propriétés rhéologiques du mélange d’étude, selon leur localisation dans le mélange étudié fonction de la nature chimique de la surface de la silice. La deuxième consistait à introduire un copolymère époxyde multifonctionnel réactif, dénommé Joncryl. La réactivité de ce copolymère avec le PLA et le PA11 a permis de compatibiliser le mélange d’étude, conduisant à une morphologie plus fine et à l’obtention de propriétés mécaniques supérieures à celles du mélange d’étude, en particulier avec l’ajout de 3%m de Joncryl. Des échantillons basés sur les mélanges compatibilisés par cette méthode ont été préparés par le procédé de fabrication additive FDM. Une étude de l’impact de ce procédé sur la morphologie et les propriétés mécaniques obtenues a été entreprise. Enfin, une meilleure réaction au feu pour le mélange compatibilisé avec 3%m de Joncryl a pu être obtenue par l’ajout combiné de nanoparticules de phyllosilicates et de RF. / Polylactic acid (PLA) is one of the biobased polymers that generates the most interest, but its thermomechanical properties need to be improved. To do that, the most used and studied methods consist of blending PLA with other polymers or adding nanoscaled mineral fillers (nanoparticles) to get a PLA based nanocomposite. This PhD work is dedicated to the elaboration and properties characterization of nanocomposites based on a filled PLA and polyamide 11 80/20 wt/wt blend. The aim is to obtain a biobased material with improved thermal, mechanical and fire reaction properties by controlling its morphology through the addition of nanoparticles and flame retardants additives.To achieve that, two compatibilization techniques, aiming to improve PLA-PA11 interfacial adhesion, were evaluated. The first one consisted of adding silica nanoparticles. Important changes of the blend morphology and rheological properties were noticed, depending on the localization of the two different silica nanoparticles used into the polymer blend phases. The second one consisted of introducing a reactive multifunctional epoxy copolymer, named Joncryl. The reactivity of this copolymer with PLA and PA11 allowed to compatibilize the blend, leading to a fine morphology and higher mechanical properties compared to those of the pristine blend. Samples of compatibilized blends obtained through this method were processed using FDM additive manufacturing process. A study of the influence of this process on the morphology and mechanical properties obtained for these samples was performed. Finally, a better fire reaction of compatibilized polymer blend with 3%wt Joncryl was obtained by the combined addition of phyllosilicates nanoparticles and flame retardants.

Polímeros líquido-cristalinos (LCPs) e poliestirenos comerciais são imiscíveis. A literatura relata melhoria na miscibilidade dessas blendas através da utilização de polímeros modificados. Misturas de polímeros com baixa massa molar são mais miscíveis do que blendas similares com polímeros de alta massa molar. Neste trabalho, blendas de poliestireno sintetizado com baixa massa molar (Mv = 11000 e 70000 g/mol) e poliestireno comercial (Mv = 223000 g/mol) e polímero líquidocristalino termotrópico sintetizado, poli(metil-1,4-dioxifenileno 4,4\'-dicarbonil-1,10- dibenzoil-oxi-decano) (Mn = 9500 g/mol, Mw = 24000 g/mol, Mw/Mn = 2,5), foram preparadas por solubilização em clorofórmio e por coprecipitação. A ocorrência ou não da miscibilidade nas amostras foram estudadas através da viscosimetria, de calorimetria exploratória diferencial (DSC) e análise térmica dinâmico-mecânica (DMTA). Os resultados obtidos foram comparados com as micrografias obtidas por microscopia eletrônica de varredura (MEV). As análises quantitativas das micrografias MEV das misturas de LCP com PS 11000 g/mol revelaram que os diâmetros das partículas de PS variaram de 27 a 52 nanômetros em blendas (PS/LCP) com composição relativa em massa de 70/30, 50/50, 30/70, formando uma estrutura micro-heterogênea. Já as misturas formadas com PS com Mv = 70000 g/mol apresentaram estrutura cocontínua para as mesmas composições de blendas, que confirmam a imiscibilidade das mesmas, conforme observado por DSC e DMTA. / Liquid crystal polymers (LCPs) and commercial polystyrene blends are known to be immiscible. The literature reports improvements on miscibility through polymer modification. Mixtures of amorphous isotropic polymers with low molar mass are more miscible than similar blends with high molar mass polymers. In this work, blends of synthesized polystyrenes with low molar masses (Mv = 11000 e 70000 g/mol) and commercial polystyrene (Mv = 223000 g/mol), and synthesized thermotropic liquid crystal polymer poly(methyl-1,4-dioxiphenylene-4,4\'-dicarbonyl- 1,10-dibenzoyl-oxydecane), (Mn = 9500 g/mol, Mw = 24000 g/mol, Mw/Mn = 2.5) were prepared by solubilization in chloroform and co-precipitation. The presence or absence of miscibility in the samples were studied by viscometry, differential scanning calorimetry (DSC), dynamic mechanic thermal analysis (DMTA). The results are compared to the morphology observed by scanning electron microscopy (SEM). Quantitative analysis of the micrographs of the blends by SEM showed that the blends with PS 11000 g/mol showed diameters of the PS particles in the range 27-52 nanometers at all compositions, forming a micro-heterogeneous structure. In contrast, the blends formed with PS Mw = 70000 g/mol showed co-continuous structure for the blends, confirming the immiscibility as observed by DSC and DMTA .

Blendas poliméricas são largamente utilizadas nas indústrias de pneus por causa de seu baixo custo e das melhores propriedades que podem ser obtidas. Quando os componentes da blenda não são miscíveis entre si, métodos de compatibilização química (utilizando agentes compatibilizantes) ou mecânica (aumentando o tempo de mistura dos elastômeros) são necessários para melhorar a compatibilidade dos componentes da mistura. Neste trabalho, o Trans-Polioctenileno (TOR) foi usado como agente compatibilizante da blenda de NR/SBR. A viscosidade Mooney, a Carga e o Alongamento na Ruptura de diversas blendas foram avaliados, utilizando um planejamento fatorial. Os resultados obtidos mostraram que o TOR tem maior influência na alteração da viscosidade Mooney, seguido pelo tempo de premix e de repasse. No caso das propriedades dinamométricas, a carga e o alongamento na ruptura são mais sensíveis às alterações do tempo de processamento dos polímeros. O TOR leva a uma ligeira diminuição destas propriedades. Baseado nos resultados estatísticos, equações de regressão para avaliar as propriedades estudadas em função da concentração de TOR e do tempo de processamento foram propostos e posteriormente verificados, utilizando blendas que não estavam incluídas no planejamento original. Os resultados foram bastante satisfatórios, tanto na determinação dos efeitos das variáveis quanto na determinação das equações. Concluiu-se que a viscosidade Mooney é mais sensível às alterações da concentração de TOR do que às alterações do tempo de mistura dos elastômeros e que as propriedades dinamométricas são mais afetadas pelo tempo de processamento. / Polymer blends are used in tyre industries because of their low cost and better properties. When the blend components are not miscible, chemical methods (using compatibilizing agents) or mechanical methods (increasing the mixture time of elastomers) of compatibilization are necessary to improve the compatibility of the components of the blend. In this work, Trans-Polyoctenylene Rubber (TOR) was used as a compatibilizing agent of the NR/SBR rubber blend. The Mooney viscosity, stress and elongation at break of different blends were evaluated, using a Factorial Design. The experimental results obtained showed that the Mooney viscosity is greatly affected by the addition of TOR whereas the dynamometric properties, the stress and elongation at break are more sensitive to the changes of processing time of polymers. Based on statistical results, regression equations to evaluate the properties studied as a function of TOR concentration and processing time were obtained and verified using blends which were not on the original design. The results were very satisfactory, either on the effects determination or on the regression equation determination. It was concluded that the Mooney viscosity is more sensitive to the alterations of TOR concentration than the changes in the processing time of the elastomers and the dynamometric properties are more affected by the processing time.

Copolymers are used to increase the interfacial strength of immiscible components and suppress recombination of the minor phase by steric hindrance. The experiments conducted in these studies are designed to investigate in situ polymer loop formation at soft interfaces and functionalized nanotube surfaces. Block copolymers are the most effective type of copolymer for compatibilization because they extend perpendicular to the interface, allowing good entanglement with the homopolymer chains. Multiblock copolymers are more effective than diblock copolymers for strengthening the interface because they can cross the interface multiple times, forming “loops” in each phase that provide entanglement points for the homopolymer. The first part of this dissertation focuses on understanding how telechelic variables influence their effectiveness to compatibilize an immiscible polystyrene (PS)/polyisoprene (PI) homopolymer blend. A fast reacting anhydride and amine telechelic pair (Anh-PS-Anh/NH2-PI-NH2) are compared with a slower reacting epoxy and carboxylic acid pair (Epoxy-PS-Epoxy/COOH-PI-COOH). Different molecular weight pairs are used to investigate the influence of end group concentrations and steric effects. We also investigate how the loading level affects the conversion of one telechelic pair. The PI telechelic has a fluorescent tag, which enables gel permeation chromatography (GPC) with fluorescence detection to be used for determining the amount of tagged PI converted and the molecular weight of the copolymer formed in situ as a function of mixing time. The effectiveness of these telechelic pairs as compatibilizers is quantified by annealing the samples and using scanning electron microscopy (SEM) to measure the domain size of the minor phase as a function of annealing time. The second part of this study investigates the grafting of polymer loops to carboxylated multiwall nanotube (COOH-MWNT) surfaces and determining the reaction rate. These polymer loops will improve the nanotube dispersion by steric hindrance and improve energy transfer by creation of polymer chain entanglements. Fourier transform infrared spectroscopy (FT-IR) is used as a novel technique to measure the quantity of Epoxy-PS-Epoxy grafted to the nanotube surface. In addition, we determined the fraction of telechelics that form loops by further reacting the grafted nanotubes with monocarboxy terminated poly(4-methylstryrene) (COOH-P4MS), which only reacts with unbound Epoxy-PS-Epoxy chain ends.

This study deals with reactively compatibilized Polyamide 6 / High Density Polyethylene blends. More precisely, it focuses on the relationship between (1) the formulation, the processing parameters in corotating twin screw extrusion and (2) the morphologies and the microstructures of blends. Multi-scale morphologies were observed by Scanning and Transmission Electron Microscopy. At the micron scale, the following morphologies were developed: nodular dispersions, stretched nodules and co-continuous morphology. As the processing conditions did not influence the types of morphology, the different morphological regions were reported in ternary diagrams. In the case of compatibilized blends, two mechanisms for morphology development have been proposed: (1) the compatibilization reaction, being very fast, leads to the formation of nano-dispersions by interfacial instabilities and (2) the standard break-up/coalescence mechanism of domains poor in copolymer could lead to the formation of morphologies up to the micron scale. Both the evolution of the largest size as a function of the composition and the distribution of sizes were modeled using percolation concepts. The stability of the morphologies was then studied either during static annealing or controlled shear or in a second step processing. The copolymer formed at the interface allows stabilizing the size of the morphologies. Finally, crystallization at lower temperature was observed by Differential Scanning Calorimetry when the polymers are confined in submicron domains.

The objective of this study is to process and characterize the compatibilized blends of acrylonitrile-butadiene-styrene (ABS) and polyamide-6 (PA6) using olefin based reactive copolymers and subsequently to utilize this blend as a matrix material in short glass fiber (SGF) reinforced composites and organoclay based nanocomposites by applying melt processing technique. In this context, commercially available epoxydized and maleated olefinic copolymers, ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) and ethylene-n butyl acrylate-carbon monoxide-maleic anhydride (EnBACO-MAH) were used as compatibilizers at different ratios. Compatibilizing performance of these two olefinic polymers was investigated through blend morphologies, thermal and mechanical properties as a function of blend composition and compatibilizer loading level. Incorporation of compatibilizer resulted in a fine morphology with reduced dispersed particle size. At 5 % EnBACO-MAH, the toughness was observed to be the highest among the blends produced. SGF reinforced ABS and ABS/PA6 blends were prepared with twin screw extrusion. The effects of SGF concentration and extrusion process conditions on the fiber length distribution, mechanical properties and morphologies of the composites were examined. The most compatible organosilane type was designated from interfacial tension and short beam flexural tests, to promote adhesion of SGF to both ABS and PA6. Increasing amount of PA6 in the polymer matrix improved the strength, stiffness and also toughness of the composites. Effects of compatibilizer content and ABS/PA6 ratio on the morphology and mechanical properties of 30% SGF reinforced ABS/PA6 blends were investigated. The most striking result of the study was the improvement in the impact strength of the SGF/ABS/PA6 composite with the additions of compatibilizer. Melt intercalation method was applied to produce ABS/PA6 blends based organoclay nanocomposites. The effects of process conditions and material parameters on the morphology of blends, dispersibility of nanoparticles and mechanical properties were investigated. To improve mixing, the screws of the extruder were modified. Processing with co-rotation yielded finer blend morphology than processing with counter-rotation. Clays were selectively exfoliated in PA6 phase and agglomerated at the interface of ABS/PA6. High level of exfoliation was obtained with increasing PA6 content and with screw speed in co-rotation mode. Screw modification improved the dispersion of clay platelets in the matrix.