In a push towards more environmentally friendly pyrotechnics, new greener pyrotechnic compositions need to be developed. A primary goal is to replace components such as lead, barium, and chromium in pyrotechnic compositions. Fused Deposition Modelling (FDM) is a 3D printing/additive manufacturing method whereby a thin filament is passed through a heated nozzle, and extruded onto a substrate in successive layers. This method of manufacturing could be used to produce pyrotechnic time delays based on suitable “green” polymer/fuel mixtures. Fluoropolymers are an attractive oxidising system for pyrotechnic use as fluorine is highly reactive and reacts relatively easily with common metallic fuels such as aluminium and magnesium to release a large amount of energy. Fluoropolymers are already in use as oxidisers and binders, especially in infrared decoy flares. PTFE has found wide use in the pyrotechnics industry, but is not melt-processible. A similar fluoropolymer, poly(chloro-trifluoroethylene) (PCTFE) was considered instead. PCTFE differs from PTFE in that one of the fluorine atoms in the TFE monomer has been replaced by a chlorine atom. The larger chlorine atom interferes with the packing of the polymer chains during polymerisation and, as such, may make it easier to process than PTFE. It was found that pure PCTFE degraded heavily during processing and was therefore precluded from any further study. Melt-processible copolymers containing PCTFE are available from industry. These copolymers contain vinylidene fluoride (VDF) in addition to the CTFE i.e. poly(CTFE-co-VDF). Two grades of copolymer were obtained from 3M: FK-800® resin and Dyneon® 31508 resin. These two polymers contain different ratios of CTFE to VDF. FK-800® resin was successfully extruded and showed minimal signs of degradation. Pyrotechnic films, containing aluminium powder as the fuel, were cast with both polymers using solvent techniques. Differential thermal analysis (DTA) was used to determine the ignition points of the compositions. All of the FK-800®-based compositions ignited at approximately 450 °C whilst all the Dyneon® 31508-based compositions ignited at approximately 400 °C. The energy output of the compositions was determined using bomb calorimetry. The experimental energy outputs of the FK-800®-based compositions correlated well with the predictions from the thermodynamic simulations. The maximum energy output, ~7.0 MJ∙kg1, occurred at a fuel loading between 30 – 35 wt.%. Except for one composition, the Dyneon® 31508-based compositions did not ignite in the bomb calorimeter. FK-800® was successfully extruded into a filament and showed minimal signs of degradation. In order to assess the impact of adding a solid filler on the mechanical properties and extrudability of the polymer, magnesium hydroxide was used as inactive model compound in place of aluminium. A filament of FK-800® and Mg(OH)2 was successfully compounded and produced using a filler loading of 30 wt.%. Compounding of the Dyneon 31508® with the magnesium hydroxide was unsuccessful. Addition of LFC-1® liquid fluoroelastomer improved the processibility of the Dyneon 31508® by lowering the melt viscosity. / Dissertation (MEng)--University of Pretoria, 2017. / Chemical Engineering / MEng / Unrestricted

O aumento da longevidade da população mundial vem acompanhado do aumento da incidência de doenças crônicas. Várias são as doenças que podem acometer esta população e entre estas, a osteoporose, que compromete a resistência e qualidade do tecido ósseo, predispondo a fraturas. Além disso, a osteoporose pode dificultar a reparação óssea. Uma técnica importante e que tem por objetivo a neoformação óssea é a regeneração óssea guiada (ROG), que utiliza uma membrana que atua como uma barreira mecânica, permitindo a criação de um espaço protegido em torno do defeito ósseo. Embora a membrana de politetrafluoretileno (PTFE) seja uma das mais utilizadas na ROG, novas membranas têm sido desenvolvidas dentre elas a membrana obtida pela associação do polímero de poli(vinilideno-trifluoretileno) e da cerâmica de titanato de bário (P(VDF-TrFE)/BT). Estudos in vitro demonstraram resultados favoráveis à membrana de P(VDF-TrFE)/BT. Desta forma, o objetivo deste estudo foi avaliar in vivo, o efeito da membrana de poli(vinilidenotrifluoretileno)/titanato de bário (P(VDF-TrFE)/BT), e como controle a de PTFE no reparo ósseo em ratas com modelo experimental para a osteoporose. Foram utilizados 30 animais, sendo 5 pertencentes ao grupo controle - Grupo 1 (G1) e 25 que foram ovariectomizados bilateralmente (OVX). Após 150 dias foram confeccionados defeitos ósseos (5 mm) na calvária e os animais OVX foram distribuídos em três grupos com relação à utilização ou não de membranas nos defeitos ósseos: Grupo 2 - nenhum tipo de membrana; Grupo 3 - membrana de PTFE e Grupo 4 - membrana de P(VDF-TrFE)/BT. Após 4 semanas, os animais foram eutanasiados e as calvárias foram coletadas para as análises histológica, histomorfométrica por micro-CT e de expressão gênica por PCR em tempo real. A análise histomorfométrica mostrou que os animais que receberam a membrana de P(VDF-TrFE)/BT apresentaram parâmetros morfométricos semelhantes ou até melhores quando comparados com os animais que receberam a membrana de PTFE. A comparação dos grupos que receberam as membranas mostrou para o grupo P(VDF-TrFE)/BT uma menor expressão para os genes RUNX2, BSP, OPN, OSX e RANKL; uma expressão semelhante para os genes ALP, OC, RANK e CTSK e uma maior expressão dos genes OPG, CALCR e MMP9. Estes resultados evidenciam que a membrana de P(VDF-TrFE)/BT pode ser considerada um biomaterial promissor para a reparação óssea em condições de osteoporose / The worldwide population age is increasing accomplished by chronic disease. The most common disease which involves the population is the osteoporosis. The bone resistance and quality of bone matrix are compromised and the fractures risks are higher. Nonetheless, the osteoporosis can avoid the bone healing. The important technique to achieve the bone neoformation is the Bone Guided Regeneration (BGR), which used a membrane as mechanic barrier to allow the new gap protection around the bone defect. Although the politetrafluoetilene (PTFE) is the most used in BGR, newest membranes have been developed as the polyvinylidene-trifluoroethylene polymer and barium titanate ceramics (P(VDF-TrFE)/BT). In vitro assays showed favorable results to P(VDF-TrFE)/BT membrane. The aim of the study was to evaluate the poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) effects, and the PTFE has been used as control on the bone repair in the osteoporosis experimental rats model. It was used 30 animals, 5 on the control group- Group 1 (G1) and 25 were ovariectomized bilaterally (OVX). Bone gaps were done 5mm size on the rats calvaria´s and the (OVX) were housed in three different groups concerned by membranes applied or not at the bone gap. Group 2 no membrane applied; Group 3 PTFE membrane and Group 4 P(VDF-TrFE)/BT membrane. Four weeks later, the animals were euthanized and the calvarias were collected to the histological analysis, histomorphometric assays by micro CT and the gene expression by the real time PCR. The histomorphometric analysis showed that the animals which received P(VDF-TrFE)/BT membrane presented similar morphometric parameters better than PTFE. The P(VDF-TrFE)/BT showed a minor expression to RUNX2, BSP, OPN, OSX e RANKL genes; the similar were to RANK e CTSK and the higher expression were to OPG, CALCR e MMP9. These results evidence that the P(VDF-TrFE)/BT could be used as promising biomaterial to bone healing under osteoporosis