The overall aim of this thesis is to describe the synthesisof branched aliphatic polycarbonates and show the potentialapplication of these polymers in the field of powder coatings.The characterization of the polycarbonates was facilitated bythe study of a series of bis-MPAdendrimers, which served asreference of perfectly branched polymers. In addition anε-caprolactone monomer with a bis-MPA pendant unit wassynthesized and polymerized in order to find an alternativesynthetic route hyperbranched polyesters. Cationic ring opening polymerization (CROP) of neopentylenecarbonate was utilized to synthesize a number of branchedpolymers. This monomer was chosen because the thermalproperties of poly(neopentylene carbonate) are promising forpowder coating applications. CROP enabled the synthesis ofbranched polymers, which are of great interest because of theirreduced melt viscosity and high functionality compared tolinear polymers. CROP of neopentylene carbonate, with a seriesof polyols including a hyper-branched polyester (Boltorn H30),in the presence of fumaric acid resulted in polymers withvaried degrees of branching and molecular weights ranging from2 000-100 000 g mol-1. Neopentylene carbonate was also used in the synthesispolycarbonate macromonomers possessing a polymerizablemethacrylate functional group at one of the chain ends. Inthjis case hydroxyethylmethacrylate was used as initiatopr inthe reaction catalyzed by methyl sulfonic acid. The MW of thismacromonomer was 2500 g mol-1and it was used to produce polymer brushes byfree radical and atom transfer radical polymerization(ATRP). An ε-caprolactone bearing a pendant bis-MPA wassynthesized and polymerized by Sn(Oct)2. Copolymerization with ε-caprolactone wasperformed to introduce linear segm,ents between the branchingpoints. The molecular weights of the homopolymer and thecopolymer were 3000 and 8000 g mol-1respectively as determined by Size exclusionchromatography (SEC) calibrated with polystyrene. SEC was used to analyze a series of bis-MPA dendrimers, andthe results were used to characterize the branchedpolycarbonates. The Mark-Houwink plots of the dendrimers wereproduced and used as reference in the characterization of thepolycarbonates. The thermal and rheological characterization of thepolycarbonates showed that the polymers were semi-crystallinewith Tgbetween 20-30 °C and Tmbetween 90-120 °C. Rheology measurementsshowed that the architecture had a considerable impact on themelt viscosity. Coating films were produced by UV curing of a series oflinear polycarbonates were functionalized with methacrylicgroups. The storage stability was tested for one week at 45°C, no coagulation of the particles was observed at theend of the testing period. The cured films showed good chemicalresistance and flexibility.

<p>The overall aim of this thesis is to describe the synthesisof branched aliphatic polycarbonates and show the potentialapplication of these polymers in the field of powder coatings.The characterization of the polycarbonates was facilitated bythe study of a series of bis-MPAdendrimers, which served asreference of perfectly branched polymers. In addition anε-caprolactone monomer with a bis-MPA pendant unit wassynthesized and polymerized in order to find an alternativesynthetic route hyperbranched polyesters.</p><p>Cationic ring opening polymerization (CROP) of neopentylenecarbonate was utilized to synthesize a number of branchedpolymers. This monomer was chosen because the thermalproperties of poly(neopentylene carbonate) are promising forpowder coating applications. CROP enabled the synthesis ofbranched polymers, which are of great interest because of theirreduced melt viscosity and high functionality compared tolinear polymers. CROP of neopentylene carbonate, with a seriesof polyols including a hyper-branched polyester (Boltorn H30),in the presence of fumaric acid resulted in polymers withvaried degrees of branching and molecular weights ranging from2 000-100 000 g mol^-1.</p><p>Neopentylene carbonate was also used in the synthesispolycarbonate macromonomers possessing a polymerizablemethacrylate functional group at one of the chain ends. Inthjis case hydroxyethylmethacrylate was used as initiatopr inthe reaction catalyzed by methyl sulfonic acid. The MW of thismacromonomer was 2500 g mol^-1and it was used to produce polymer brushes byfree radical and atom transfer radical polymerization(ATRP).</p><p>An ε-caprolactone bearing a pendant bis-MPA wassynthesized and polymerized by Sn(Oct)₂. Copolymerization with ε-caprolactone wasperformed to introduce linear segm,ents between the branchingpoints. The molecular weights of the homopolymer and thecopolymer were 3000 and 8000 g mol^-1respectively as determined by Size exclusionchromatography (SEC) calibrated with polystyrene.</p><p>SEC was used to analyze a series of bis-MPA dendrimers, andthe results were used to characterize the branchedpolycarbonates. The Mark-Houwink plots of the dendrimers wereproduced and used as reference in the characterization of thepolycarbonates.</p><p>The thermal and rheological characterization of thepolycarbonates showed that the polymers were semi-crystallinewith T_gbetween 20-30 °C and T_mbetween 90-120 °C. Rheology measurementsshowed that the architecture had a considerable impact on themelt viscosity.</p><p>Coating films were produced by UV curing of a series oflinear polycarbonates were functionalized with methacrylicgroups. The storage stability was tested for one week at 45°C, no coagulation of the particles was observed at theend of the testing period. The cured films showed good chemicalresistance and flexibility.</p>

The physical properties of rigid PVC products can be related to formulation, preblending and processing characteristics. A fuller understanding between these interrelations involves investigation of a complete processing system from powder additives to end product. A knowledge of these relationships can lead to a optimisation of formulation aspects and processing conditions. Fillers and lubricants have often been incorporated into PVC compounds on a empirical basis, however in this investigation a wide range of compositions were carefully chosen and included a calcium carbonate filler at levels up to 40 phr. These were dry blended and then characterised by bulk density and filler content. The premix was processed using an instrumented twin screw extruder, a wide processing 'window' being chosen to provide a product range with large variations in fusion level. Further compounds were extruded, incorporating two different impact modifiers. The extrudates was assessed for degree of fusion by differential thermal analysis, solvent immersion and microscopy. The filler distribution, surface appearance and residual grain structure was observed using a range of microscopy techniques and the results related to operating conditions. A measure of fusion level was obtained from mast er curves of heat of fusion versus processing temperature'. The filler level did not influence the degree of fusion. Various mechanical properties of the pipe were assessed. Impact performance was measured using an instrumented falling weight impact tester and the subsequent fracture behaviour depended on the composition and fusion level. Impact properties were dramatically reduced at a critical filler content and ductile-brittle transition temperatures were obtained for the extrudates by testing at low and high temperatures. Tensile properties did not follow the trends observed during impact testing but indicated a progressive reduction in tensile properties with increasing filler content.

Silicone rubber high voltage insulators are sometimes colonised by microorganisms which form a biofilm on the surface of the infected unit. In this work insulators exposed to the outdoor environment in Sweden, Sri Lanka and Tanzania respectively have been studied. The biofilms colonising the insulators were shown to be of roughly the same composition regardless of their origin. Algae in association with bacteria dominated the biofilms and provided nutrition to mold growth. The isolated microorganisms were further used to study the effect of a biofilm on different silicone rubber materials. New tools for diagnosing biological growth on polymeric materials were developed and used to analyse the silicone rubber samples. No evidence of biodegradation of the polydimethylsiloxane (PDMS) molecule has been found in this work. However, this does not mean that PDMS rubbers used in high voltage insulators can be called bioresistant. Silicone insulating materials always contain additives and these may promote or hinder growth. For this reason, an extensive test program was developed, in order to evaluate the effect of different additives on the degree of biological growth. The program spanned from fast and easy methods, useful for screening large amount of samples, to the construction of specially designed microenvironment chambers in which mixed biofilms, similar to those formed on the surface of silicone rubber insulators in the field, were successfully grown. The test program showed that the flame retardant zinc borate protected the materials, whereas alumina trihydrate (ATH) did not hinder biological growth. On the contrary, environmental scanning microscopy (ESEM) in combination with X-ray energy dispersive spectroscopy (EDS) showed that the surface roughening caused by the addition of ATH to the silicone rubber matrix made the materials more difficult to clean. Furthermore when the hydrophobic surface of a silicone rubber insulator is covered by a hydrophilic biofilm this leads to a reduction of the surface hydrophobicity of the material. This may alter the electrical properties of the insulator. It is therefore important to develop methods to identify biofouled units. In this work, laser-induced fluorescence (LIF) spectroscopy was explored as a tool for the detection of biofilms on silicone rubbers. The experiments revealed that weak traces of algae or fungal growth, even those not visible to the naked eye, could be detected by this technique. In addition, it was shown that photography and subsequent digital image analysis could be utilised to estimate the area covered by biofilm growth. The results obtained indicate that LIF spectroscopy in combination with image analysis could be used for field diagnostics of biological growth on insulators in service.

La détérioration des infrastructures au Canada due à la corrosion des armatures est l'un des défis majeurs de l'industrie de la construction. Les progrès récents dans la technologie des polymères ont conduit au développement d'une nouvelle génération de barres d'armature à base de fibres renforcées de polymères (PRF), (en particulier les fibres de verre). Ces barres, résistant à la corrosion, ont montré un grand potentiel d'utilisation pour mieux protéger les infrastructures en béton armé contre les effets dévastateurs de la corrosion. Avec la publication du nouveau code S807-10 "Spécifications pour les polymères renforcés de fibres" et la production de barres en PRF de très haute qualité, celles-ci représentent une alternative réaliste et rentable par rapport à l'armature en acier pour les structures en béton soumises à de sévères conditions environnementales. La conception des éléments en béton armé de barres en PRF est généralement gouvernée par l'état de service plutôt que l'état ultime. Par conséquent, il est nécessaire d'analyser les performances en flexion et le comportement en service en termes de déflexion et de largeur de fissures des éléments en PRF sous charges de service et de vérifier que ces éléments rencontrent les limites des codes. Aussi, de récents développements dans l'industrie des PRF ont conduit à l'introduction des barres en PRF avec des configurations de surface et des propriétés mécaniques différentes. Ces développements sont susceptibles d'affecter leur performance d'adhérence et, par conséquent, la largeur des fissures dans les éléments en PRF. Cependant, les codes de conception et les guidelines de calcul fournissent une valeur unique pour le coefficient d'adhérence (k[indice inférieur b]) en tenant compte des configurations de surface et en négligeant le type de barre en PRF, le diamètre de la barre, et le type de béton et de sa résistance. En outre, le code canadien S807-10 "Spécifications pour les polymères renforcés de fibres" fournit une étape en classant les barres en PRF par rapport à leur module d'élasticité (E[indices inférieurs frp]). Ces classifications ont été divisées en trois classes : Classe I (E[indices inférieurs frp]<50 GPa), Classe II (50 GPa [plus petit ou égal] E[indices inférieurs frp]< 60 GPa) et Classe III (E[indices inférieurs frp] [plus grand ou égal] 60 GPa). Ce programme de recherche vise à étudier expérimentalement le comportement en flexion des éléments en béton en service armé avec différents paramètres sous charges statiques. Le programme expérimental est basé sous plusieurs paramètres, dont les différents ratios de renforcement, différents types de barres (différentes classes comme classifiées par le CAN/CSA S807-10), le diamètre et la surface de la barre, la configuration ainsi que la résistance du béton. De plus, les recommandations actuelles de design pour les valeurs de k[indice inférieur b] et la vérification de la dépendance des valeurs de k[indice inférieur b] sur le type de barres (verre ou carbone), le diamètre des barres et le type de béton et sa résistance ont été étudiées. Le programme expérimental comprenait la fabrication et les essais sur 33 poutres à grande échelle, simplement appuyées et mesurant 4250 mm de long, 200 mm de large et 400 mm de hauteur. Vingt et sept poutres en béton ont été renforcées avec des barres en PRF à base de verre, quatre poutres en béton ont été renforcées avec des barres de PRF à base de carbone, et deux poutres ont été renforcées avec des barres en acier. Toutes les poutres ont été testées en flexion quatre points sur une portée libre de 3750 mm. Les paramètres d'essai étaient: le type de renforcement, le pourcentage d'armature, le diamètre des barres, configurations de surface et la résistance du béton. Les résultats de ces essais ont été présentés et discutés en termes de résistance du béton, de déflection, de la largeur des fissures, de déformations dans le béton et l'armature, de résistance en flexion et de mode de rupture. Dans les trois articles présentés dans cette thèse, le comportement en flexion et la performance des poutres renforcées de barres en PRFV et fabriquées avec un béton normal et un béton à haute performance ont été investigués, ainsi que les différentes classes de barres en PRFV et leurs configurations de surface. Les conclusions des investigations expérimentales et analytiques contribuent à l'évaluation des équations de prédiction de la déflection et des largeurs de fissures dans les codes de béton armé de PRF, pour prédire l'état de service des éléments en béton renforcés de PRF (déflection et largeur de fissures). En outre, à la lumière des résultats expérimentaux de cette étude, les équations de service (déflection et largeur des fissures) incorporées dans les codes et guidelines de design [ACI 440.1R-06, 2006; ISIS Manual No.3, 2007; CAN/CSA-S6.1S1, 2010; CAN/CSA-S806, 2012] ont été optimisées. En outre, les largeurs de fissures mesurées et les déformations ont été utilisées pour évaluer les valeurs courantes de k[indice inférieur b] fournies par les codes et les guidelines de calcul des PRF. En outre, les conclusions ne prennent pas en charge la valeur unique de k[indice inférieur b] pour les barres en PRF de types différents (carbone et verre) avec des configurations de surface similaires et s'est avéré être dépendant du diamètre de la barre.

<p>The interest for polypropylene/cellulose composites has experienced a great increase in different applications such as car interiors and construction materials. Cellulose fibres are inexpensive, renewable, biodegradable, they present lower density and their mechanical properties can be compared to those of inorganic fillers. However, several factors must be considered when designing polypropylene/cellulose composites: the poor compatibility between the hydrophilic fibres and the hydrophobic thermoplastic matrix leads to a weak interface, which has to be improved by coupling agents; the hydrophilic nature of the fibres makes them very sensitive towards water absorption, which also leads to a loss of properties and swelling with subsequent dimensional instability; the reduced thermal stability of cellulose fibres leads to degradation of the fibres at thermoplastic processing temperatures producing odours in the final material; and finally the properties of composites are greatly influenced by the structure, size and quality of the fibres.</p><p>Pulp fibres modified by different methods in order to enhance the compatibility fibre-matrix, were tested. Modified fibres led to improved mechanical properties and thermal behaviour when used in composites with recycled polypropylene.</p><p>Four different types of natural fibres were used as reinforcement in two different polypropylene types: virgin and recycled polypropylene. The mechanical properties of the composites were mostly dependent on the fibre loading and slightly dependent on the type of fibre. Moreover, water absorption kinetics was studied by the Fickian diffusion theory. After absorption, a remarkable loss of properties was observed.</p><p>Hydrolysed cellulose fibres showed a greater enhancing effect on polypropylene than non-hydrolysed cellulose fibres. This is attributed to the greater mechanical properties of reduced cellulose structures.</p><p>The effect of using cellulose fibres in PP/clay nanocomposites was also studied. The interaction between the clay particles and the cellulose fibres and the combined effect of both reinforcements were believed to be the main reasons for the enhancing properties.</p>

The interest for polypropylene/cellulose composites has experienced a great increase in different applications such as car interiors and construction materials. Cellulose fibres are inexpensive, renewable, biodegradable, they present lower density and their mechanical properties can be compared to those of inorganic fillers. However, several factors must be considered when designing polypropylene/cellulose composites: the poor compatibility between the hydrophilic fibres and the hydrophobic thermoplastic matrix leads to a weak interface, which has to be improved by coupling agents; the hydrophilic nature of the fibres makes them very sensitive towards water absorption, which also leads to a loss of properties and swelling with subsequent dimensional instability; the reduced thermal stability of cellulose fibres leads to degradation of the fibres at thermoplastic processing temperatures producing odours in the final material; and finally the properties of composites are greatly influenced by the structure, size and quality of the fibres. Pulp fibres modified by different methods in order to enhance the compatibility fibre-matrix, were tested. Modified fibres led to improved mechanical properties and thermal behaviour when used in composites with recycled polypropylene. Four different types of natural fibres were used as reinforcement in two different polypropylene types: virgin and recycled polypropylene. The mechanical properties of the composites were mostly dependent on the fibre loading and slightly dependent on the type of fibre. Moreover, water absorption kinetics was studied by the Fickian diffusion theory. After absorption, a remarkable loss of properties was observed. Hydrolysed cellulose fibres showed a greater enhancing effect on polypropylene than non-hydrolysed cellulose fibres. This is attributed to the greater mechanical properties of reduced cellulose structures. The effect of using cellulose fibres in PP/clay nanocomposites was also studied. The interaction between the clay particles and the cellulose fibres and the combined effect of both reinforcements were believed to be the main reasons for the enhancing properties. / QC 20101011

There is a growing awareness of the risks of pollution in biological systems and one potential problem is the synthetic antioxidants, used for e.g. the stabilisation of polymeric materials. Natural antioxidants are an interesting alternative, if the high efficiency and thermal stability of the synthetic compounds can be reached. In the work described in this thesis, vitamin E (alfa-tocopherol) was studied as a natural antioxidant for the stabilisation of one of the major plastics, polyethylene (PE). The dependence of the surrounding environment for the efficiency of alfa-tocopherol in polyethylene (PE), throughout thermal aging, was characterised by sensitive techniques. Two techniques which have shown a high sensitivity in oxidation detection of polymers; chemiluminescence (CL) and gas chromatographic analysis, were compared with the commonly used methods, infrared spectroscopy (FT-IR) and thermal analysis. Three different additive systems were selected as active domains for -tocopherol in PE. Two of these contained carboxylic acid groups, poly (ethylene-co-acrylic acid) (EAA) and polyTRIM/PAA core-shell particles (Core), and the third, oat starch, had no such groups. The additives containing carboxylic groups improved the long-term efficiency of alfa-tocopherol in PE, according to carbonyl index measurements made by FT-IR, while the additive without carboxylic acid groups gave no improvement. The amount of carboxylic acids emitted from the materials after thermal aging, assessed by head-space solid-phase microextraction (HS-SPME) and gas chromatography-mass spectroscopy (GC-MS), also showed that EAA increased the antioxidant efficiency of alfa-tocopherol, whereas the Core system showed lower antioxidant efficiency. Reference systems containing the synthetic antioxidant Irganox 1076 and EAA or oat starch had the same performance as the materials stabilised with only the antioxidants. CL measurements in an inert atmosphere (TLI) have earlier been shown to give earlier oxidation detection than carbonyl index measurements in unstabilised PE. In this work, the TLI analysis and the carbonyl index measurements had the same sensitivity in the detection of oxidation in the stabilised materials. Assessment of low-molecular weight carboxylic acids in PE during the aging was made by gas chromatographic analysis together with solid-phase extraction. Propanoic acid showed the best correlation with the carbonyl index measurements, even if the carbonyl index showed earlier detection of oxidation. It was also found that TLI and CL in an oxidative atmosphere (CL-OIT) had the same sensitivity and were in accordance for all of the materials, with exception of the materials containing EAA and alfa-tocopherol or Irganox 1076. CL-OIT was also compared to the oxygen induction time determined by thermal analysis. / QC 20100921