In this study, novel lamination techniques are introduced for the coating of fabrics in order to enhance their ballistic/needle penetration resistance properties. Pressure sensitive adhesive (PSA) was used to create flexible ballistic composite panels with ultra-high molecular weight polyethylene (UHMWPE) fabric. An increase in processing pressure from 0.1 to 8 MPa significantly improved the ballistic performance against 9 mm FMJ ammunition of UHMWPE composite. The number of layers required to stop the bullet were reduced from 45 to 22 layers after lamination without a significant increase in stiffness. The backface signature (BFS) was reduced from 19.2 mm for the 45 layer neat samples to 11.7 mm for the 25 layer laminated samples pressed at 8 MPa. The second lamination technique used patterned thermoplastic hot film to create flexible UHMWPE composite laminates. Hexagonal patterns were cut through a heat transfer vinyl carrier sheet using a vinyl cutter and was used as a mask between the UHMWPE fabric and hot film during heat treatment in order to have the fabric coated only on those regions. The patterns had a nominal diameter of 27.9 mm with a 1 mm gap between each region. A significant improvement in the ballistic performance of UHMWPE fabric is observed after coating each individual layer with patterned hot film and 25 layers of laminated fabric were sufficient to stop a .357 magnum FMJ ammunition compared to unlaminated neat fabric which required 45 layers to stop the bullet. Patterning of the hot film did not negatively affect the ballistic performance of the composite laminates whilst increasing their flexibility in relation to using plain hot film with no patterning involved. It resulted in a 21% increase in bending angle of the 25 layer samples v and 9.5% reduction in bending length of the single plies which both relate to greater flexibility because a higher bending angle and lower bending length correlates to more flexibility. The same technique of patterning of hot film is used in the lamination of woven cotton fabric to enhance needle penetration resistance properties whilst maintaining the flexibility. Patterns used in this study were either hexagonal or a combination of hexagons and triangles and the nominal diameter ranged from 2.6-13.5 mm. The lamination significantly improved the 25G hypodermic needle penetration resistance of the fabric. By increasing the number of laminated fabric plies from 1 to 2, the needle resistance force increased by up to 150%. However, in comparison to just one layer, the flexibility decreased by about 12% to 26% for two and three layers, respectively. It was observed that reducing the sizes of the patterns improved the flexibility of the samples by up to 30% without compromising the needle penetration resistance. / Thesis / Master of Applied Science (MASc)

No description available.

The battery separator is a component of the conventional battery that for long has been overlooked. Just because it’s the only inactive component, doesn’t mean it’s any less important for the battery cell. Recent trends point to an immense growth of the electrical vehicle-industry, and by so, also the lithium-ion battery separators market. This is because the lithium-ion battery is the most common battery type in commercial electrical vehicles. In one of the major manufacturing processes of the separator, mineral oil is used, to achieve a porous film. This study aims to evaluate different oils interaction with the polymer resin in the manufacturing process. Since most oils used in the battery separator industry today use paraffin rich oils, oils with different naphthenic content is tested to find correlations between the oils properties and the crystallinity or the porosity. No correlations for either the porosity or the crystallinity could be made to the oil’s properties. The images taken with the SEM was not enhanced enough to study the pores themselves or the pore structure of the films. For future studies it is recommended to collect more data to identify outliers so more accurate values are obtained. The methodology needs to be verified to ensure the procedure is reproducible. For the study of the pores and the pore structure, an FE-SEM should be used to achieve greater quality enhancement images on the surface of the films. / Batteri separatorn är en komponent i det konventionella batteriet som länge har förbisetts. Bara för att den är en inaktiv komponent, betyder inte att den är mindre viktig för battericellens prestation. Trender idag pekar mot en enorm tillväxt inom elbils-industrin, och med det även litium-jon batteriseparatorns marknad. Det är för att litium-jon batteriet är det batteriet som vanligen används kommersiellt idag i elbilar. I en av de två stora industriella tillverkningsprocesserna används olja för att åstadkomma en porös film. Denna studie syftar på att utvärdera olika oljors interaktion med polymeren i denna tillverkningsprocess. Eftersom de flesta batteriseparator-industrier idag använder paraffinrik olja så testas oljor med olika mycket naftalensikt innehåll för att hitta korrelationer mellan oljornas egenskaper och kristalliniteten eller porositeten hos filmerna. Inga korrelationer för porositeten eller kristalliniteten kunde göras till oljornas egenskaper. Bilderna tagna med SEM var ej tillräckligt förstorade för att kunna studera vare sig porstorleken eller porstrukturen hos filmerna. För framtida studier rekommenderas att samla in mer data för att kunna utskilja ”outliers” i datan, för att erhålla mer korrekta värden. Metodiken måste även verifieras för att säkerställa att proceduren är reproducerbar. För att studera porerna och porstrukturen, borde en FE-SEM användas för att få mer förstorade bilder med bättre kvalité på filmernas yta.

Regardless of the simplicity in molecular structure, polyethylene is used in high-performance applications such as medical prostheses and ballistics. Recent advancements in homogeneous catalysis produced UHMWPE in the low-entangled or dis-entangled state that allowed solvent-free-solid-state processing to achieve ultimate mechanical properties ever achieved for a synthetic polymer. Although several homogeneous complexes are known to produce dis-UHMWPE, existing major challenges are uncontrolled nascent polymer morphology, as a consequence reactor fouling/wall sheeting. In such a scenario, a heterogeneous catalyst that can produce dis-UHWMPE to an extent that the characteristics and properties equivalent to that obtained in homogeneous condition, remains an open challenge. The thesis will discuss the know-how for the synthesis of dis-UHMWPE via heterogeneous route to facilitate industrial production by following fundamental understanding of polymerization catalysis, physics, processing, and testing. In this thesis, in-situ formed nano activator/support MgClx/EtnAly(2-ethyl-1-hexoxide)z is employed with a highly active bis[N-(3-tert-butylsalicylidene)pentafluoroanilinato] titanium (IV) dichloride (Cat. 1) for synthesis of dis-UHMWPE. In addition, the relatively easy formation of the MgClx/RnClmAly(OR’) activators/supports allows tailoring by the selection of different aluminum-alkyls and alcohols, giving access to a variety of co-catalysts. This investigation resulted in UHMWPE having Mw from 3 to an unprecedented 43 M g/mol and Ð from 3 to 38 with very high activities up to 2750 kgPE molcat.-1 bar-1 h-1. The adopted route resulted in nano-support that allows tailoring of the entangled state and control over the nascent morphology without reactor fouling, thus providing feasibility of pursuing the polymerization via a continuous process. The nascent polymer shows formation of single crystals of linear UHMWPE and is suggestive of the low-entangled state. The topological differences, with the commercial entangled sample, are identified solid-state NMR, DSC, and rheology. The disentangled crystals allowed desired chain orientation for securing unprecedented tensile modulus (>200 N/tex) and tensile strength (>4.0 N/tex) via solid-state processing. Additionally, the investigation of creep response in the uniaxial tapes has revealed strong influence of molecular weight and entanglement density. These unique characteristics and unprecedented mechanical properties are equivalent to that perceived using a homogeneous catalysis and are the first of their kind achieved for a polymer synthesized using a heterogeneous catalysis.

No description available.

Ce travail s'est concentré sur la compréhension de l'influence de la formulation et plus spécifiquement de la silice précipitée sur la résistivité électrique de séparateurs en polyéthylène destinés à des batteries au plomb. Les séparateurs de batteries en polyéthylène sont composés de silice précipitée, de polyéthylène ultra haute masse molaire (UHMWPE) et d'huile organique. La première partie de ce travail a été d'élaborer à l'échelle du laboratoire, des membranes modèles en polyéthylène. La seconde a été de comprendre l'influence de certains facteurs sur les propriétés structurales et physicochimiques des membranes. Ces facteurs sont principalement la quantité d'huile, la quantité et le grade de silice précipitée, les conditions de température lors de la cristallisation de la membrane et le mode de mise en œuvre utilisé. Les influences des quantités d'huile et de silice sur la cristallisation du polyéthylène sont méticuleusement étudiées, montrant que l'huile aide à augmenter la cristallinité finale de l'UHMWPE et que la silice joue un rôle de réservoir d'huile. Il a également été mis en évidence que la quantité ainsi que le grade de silice influencent la quantité de porosité de la membrane mouillable par l'électrolyte. La présence de silice en surface des pores est responsable de la mouillabilité de la membrane. Un paramètre empirique a donc été proposé dans le but de pouvoir quantifier l'efficacité de l'état de dispersion/distribution de la silice précipitée dans la membrane. Pour terminer, pour une formulation et un même mode de mise en œuvre, il est possible de discriminer l'efficacité des grades de silice précipitée pour l'application séparateur de batterie / This work is devoted to understand the effect of the formulation and more specifically of the precipitated silica on the resistivity of the PE-separators. The PE-separators are designed for the lead-acid batteries. PE-separators are composed of precipitated silica, ultrahigh molecular weight polyethylene (UHMW-PE) and organic oil. The first part of this work was to elaborate PE-separator models at a laboratory scale. Then, the factors impacting the structural and physico-chemicals properties of PE-separators were investigated. These factors are mainly the amounts of oil, precipitated silica, the grade of the precipitated silica, the temperature conditions of crystallization and the device used to elaborate the membrane. The influence of the amounts of oil and precipitated silica on the crystallization of the polyethylene wasthoroughly described showing that the oil helps to increase the final crystallinity of UHMWPE and that the silica plays a role of oil reservoir. Moreover, it was shown that the amount and the grade of precipitated silica have an influence on the wettable part of the porosity of the PE-separators. The coating of the pores by the precipitated silica is responsible of the wettability of the membranes by the electrolyte. Thus, an empirical parameter has been proposed in order to quantify the efficiency of the dispersion and distribution of the precipitated silica in the membrane. The more the membranes are wettable by the electrolyte the more the resistivity of the membranes is decreased. To finish, for a same amount of components and a same method of processing, it is possible to discriminate the efficiency of each grade of precipitated silica for the battery separator application

Le polyéthylène à ultra haute masse molaire (UHMWPE) présente une viscosité si forte à l'état fondu que seuls des procédés de mise en forme de type frittage peuvent être employé. Ce procédé rarement utilisé pour les polymères reste peu étudié. En particulier les deux principaux mécanismes généralement mentionnés que sont le réenchevêtrement et la cocristallisation aux interfaces sont difficilement observables séparément. Le UHMWPE, grâce à sa très haute viscosité à l'état fondu et grâce à son plateau caoutchoutique extrêmement étendue en température, peut faire l'objet d'essais mécaniques à la fois à l'état semi-cristallin et à l'état fondu. Des poudres natives de UHMWPE de masses molaires comprises entre 0,6 et 10,5 Mg.mol-1 sont utilisées comme matériau de départ pour leur mise en oeuvre par frittage. La consolidation des interfaces par soudage des particules a été effectuée sous pression à différentes températures supérieures au point de fusion et pour différentes durées. Des expériences de traction effectuées soit à température ambiante soit au-dessus du point de fusion ont permis de distinguer le rôle de l'interdiffusion des chaînes au travers des interfaces de celle de la cocristallisation dans les mécanismes de soudage de particules. Il s'est avéré qu'un soudage efficace se produit dans une échelle de temps très courte. La très faible influence de la durée de frittage par rapport à celle de la température de frittage a prouvé que l'interdiffusion des chaînes n'est pas régie par un mécanisme de reptation. L'explosion à la fusion des cristaux " hors-équilibre " de la poudre native est suggérée être le mécanisme principal permettant un réenchevêtrement dans un laps de temps beaucoup plus court que celui de la reptation. La cocristallisation est un phénomène si efficace dans la consolidation de l'interface à l'état solide qu'elle masque significativement la cinétique de réenchevêtrement gouverné par la température, visible dans les tests mécaniques à l'état fondu.

Ultra high molecular weight polyethylene (UHMWPE) is a polymer commonly used in various applications, particularly in hip joint replacements. Despite its good performance, it is susceptible to oxidation degradation, which can be mitigated with the addition of vitamin E, and to excessive wear against metal countersurfaces, which can potentially be improved with the addition of nanoparticles. In this work, sixteen newly developed UHMWPE nanocomposites with different nanofillers (multi-walled carbon nanotubes, graphene oxide and nanodiamonds), blended with and without vitamin E, and both irradiation crosslinked and non-crosslinked were studied. Thermomechanical characterisation (dynamic mechanical analysis and thermogravimetric analysis) and tribological pin-on-disc testing showed that both nanofillers and the addition of vitamin E ensured improved the performance of the nanocomposites compared to the virgin UHMWPE. Vitamin E improved the oxidative and thermal stability of UHMWPE, decreased the wear and increased the coefficient of friction. The nanoparticle reinforcements contributed to improved thermal stability to some degree and decreased the wear. Crosslinking was also shown to result in improved thermomechanical performance, although it appears that the addition of vitamin E inhibits the crosslinking process.

O presente trabalho tem como objetivo estudar o efeito da carga normal aplicada, da velocidade de deslizamento, do acabamento superficial e do tipo de contra-corpo, na degradação dos materiais poliméricos POM e UHMWPE, resultante do contato deslizante contra corpos rígidos. Para tanto, foram realizados ensaios de desgaste em um tribômetro do tipo pino-contra-disco, com os pinos de materiais poliméricos e os discos de alumina e aço inoxidável. Nos ensaios de desgaste, utilizou-se 3 valores de carga, 3 velocidades de deslizamento e 3 níveis de acabamento superficial do contra-corpo. Para cada condição de ensaio, foram realizadas 3 repetições. Durante os ensaios, foram monitoradas a temperatura na interface dos materiais, a força de atrito e a posição vertical do pino. O deslocamento vertical do pino devido ao desgaste foi utilizado para a determinação da taxa de desgaste do polímero. A distância percorrida pelos pinos sobre o disco foi de 3.500 metros. Os ensaios foram realizados em ambiente com umidade relativa controlada em 50 ± 5 %. As análises por microscopia eletrônica de varredura das superfícies de desgaste dos pinos e dos discos indicaram a ocorrência de três tipos de mecanismos de desgaste: a abrasão, a fadiga e a transferência de filme (adesão). Para analisar o comportamento do desgaste mediante as influências estudadas, um parâmetro de severidade global (PVR/DD) é proposto. No parâmetro PVR/DD, considerou-se a relação entre um fator mecânico (condição de pressão e velocidade, PV), um fator topográfico (rugosidade do contra-corpo, R) e um fator térmico (difusividade térmica dos materiais em contato, DD). Verificou-se que os níveis de desgaste dos materiais poliméricos são influenciados pela condição de severidade global do contato; entretanto, o efeito preponderante foi devido ao tipo de material do contracorpo. Como foi observado que o deslocamento vertical ocorre devido não somente ao desgaste, mas também à fluência do polímero, à atuação de diferentes mecanismos de desgaste e ao fenômeno da fusão, os resultados de cada material de polímero estudado foram organizados na forma de mapas em função da severidade global, salientando as regiões de atuação de cada fenômeno. / The present investigation aims to study the degradation of polymeric materials resulting from the sliding contact against rigid bodies. The effect of some tribological influences, such as the applied load, the sliding velocity, the surface roughness and the counter-face material, were investigated. Experimental sliding wear tests were performed through a pin-on-disc tribometer, with the pins of polymeric material and the discs of alumina and stainless steel. The testing conditions of the wear tests encompassed three values of load (normal pressure) and three values of sliding velocity, or PV values, and three ranges of disc surface roughness. Three tests were performed in each condition. The interface temperature between the specimens, the friction force and the vertical position of the pin were monitored along the tests. The vertical displacement of the pin, resulting from the wear, was used for the determination of the polymer wear rate. The total sliding distance was of 3,500 meters. During the tests, the relative humidity of the environment was controlled to 50 ± 5 %. Analyses on the worn surfaces of pins and discs performed through scanning electronic microscopy indicated the occurrence of three wear mechanisms: abrasion (scratches), fatigue (waves) and adhesion (transfer film). In order to analyze the wear behavior of the polymer, a parameter of global severity of the contact (PVR/DD) was proposed. This parameter comprised a mechanical factor (the PV values), a topographic factor (the disc roughness) and a thermal factor (the thermal diffusivity of the materials in contact). It was possible to verify that the polymer wear depended on the level of global severity of the contact, where the major effect was due to the counterface material. It was also observed that the vertical displacement of the pin occurred not only due to the wear phenomena, but also due to the creep and the melting of the polymer, both depending on the testing condition. The creep and the melting phenomena were considered in the polymer degradation behavior, organizing the results of polymeric pin displacement in degradation maps, showing the boundaries of each observed phenomena, in function of the contact global severity.

Made available in DSpace on 2017-07-21T20:42:32Z (GMT). No. of bitstreams: 1 dissertacao - arquivos para publicar.pdf: 1279347 bytes, checksum: a251737807cada580c8a5af0b1c88bff (MD5) Previous issue date: 2010-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work the ultra high molecular weight polyethylene grafting with maleic anhydride by ball milling process was studied. UHMWPE with molecular weight of 8x106 g.mol-1, maleic anhydride and benzoyl peroxide were used. The ball milling process was performed in Attritor and Spex mills. The milling time, peroxide concentration and, in case of Attritor mill, the rotation, were the variables studied. We used two distinct levels for each variable and all possible combinations were studied with the use of statistical analysis for better interpretation of the results. The residual maleic anhydride was extracted from the samples by soxhlet extractor with acetone as a solvent. FTIR, SEM, XRD and bulk density measurements were performed for characterization. FTIR results revealed that the UHMWPE graft with maleic anhydride occurred for the processing in both mills. In case of the Attritor mill, the milling time and the rotation were the most influent variables in UHMWPE grafting. The peroxide concentration also affected the process, but with less intensity. For the Spex mill processing, the milling time was the most influent variable in grafting process, with the peroxide concentration again affecting less the process. The ball milling modified the polymer particles morphology, transforming from sphere to flake like. This transformation occurred in different levels, being correlated with milling time and rotation in case of Attritor mill. According to the change in the shape of the polymer particles, the bulk density was also affected by the same variables. The polymer crystalline structure was studied by XRD, where the influence on the variables was determined for the formation of monoclinic and orthorhombic phases. It was found that for the Attritor mill, the milling process induces the formation of a monoclinic phase, but it proved independent of the variables involved in the ball milling process. To the Spex mill processing, no change was detected in the concentration of the monoclinic phase, probably due to the warming occurred in the process that promotes the monoclinic-orthorhombic inversion around 70 º C. The ball milling also affected the thermal properties of the polymer, such as temperature and enthalpy of melting and crystallization. In this case, any variable proved influential in differentiating these thermal properties of milled samples in different conditions. The only significant difference was observed between the thermal properties of the milled samples for the no milled sample. / No presente trabalho foi estudada a funcionalização do polietileno de ultra alta massa molar com anidrido maleico através do processo de moagem de alta energia. Utilizou-se o PEUAMM de massa molar de 8 milhões de gramas por mol, anidrido maleico e peróxido de benzoíla. As moagens foram realizadas nos moinhos Attritor e Spex e as variáveis envolvidas no processo foram o tempo de moagem, a concentração de peróxido e, no caso do moinho Attritor, a rotação. Foram utilizados dois níveis distintos para cada variável e todas as combinações possíveis foram estudadas, com a utilização de análise estatística para a melhor interpretação dos resultados. O anidrido maleico não reagido foi extraído das amostras moídas por meio de extrator soxhlet com o emprego de acetona. As caracterizações foram efetuadas através de FTIR, DSC, MEV, DRX e medidas de densidade aparente. Os resultados de FTIR das amostras revelaram que a funcionalização do PEUAMM com anidrido maleico ocorreu para o processamento em ambos os moinhos. No caso do moinho Attritor, o tempo de moagem e a rotação foram as variáveis mais influentes na funcionalização do PEUAMM. A concentração de peróxido também se mostrou influente no processo, mas de forma menos intensa. Para o processamento no moinho Spex, o tempo de moagem foi a variável mais influente no processo de funcionalização, com a concentração de peróxido novamente influenciando de maneira menos intensa. A moagem modificou a morfologia das partículas do polímero, transformando-as de aproximadamente esféricas para “flakes”. Esta transformação ocorreu em diferentes níveis, relacionados com o tempo de moagem e com a rotação do moinho no caso do Attritor. De acordo com a modificação no formato das partículas do polímero, a densidade aparente também foi afetada pelas mesmas variáveis. A estrutura cristalina do polímero foi estudada através dos dados de DRX, onde foi verificada a influência das variáveis na formação das fases monoclínica e ortorrômbica do polímero. Obteve-se que para o moinho Attritor o processo de moagem induziu a formação de fase monoclínica, mas sua quantidade se mostrou independente das variáveis envolvidas no processo de moagem. Para o processamento via Spex nenhuma mudança foi detectada na concentração da fase monoclínica, provavelmente devido ao aquecimento ocorrido no processo e que promove a reversão monoclínica-ortorrômbica por volta de 70ºC. A moagem também afetou propriedades térmicas do polímero, como temperaturas e entalpias de fusão e cristalização. Neste caso, nenhuma variável se mostrou influente para diferenciar tais propriedades térmicas das amostras moídas nas diferentes condições. A diferença significativa observada foi apenas entre propriedades térmicas de amostras moídas em relação à amostra não moída.