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The in-situ synthesis of piezoelectric-reinforced metal matrix composites has been attempted with a variety of target matrix and reinforcement materials using reaction synthesis and high energy ball milling. Zinc oxide (ZnO) and barium titanate (BaTiO₃) have been successfully synthesized within copper and iron matrices in a range of volume percentages using reaction synthesis. The microstructures of these composites have been analyzed and found to partially consist of an interpenetrating microstructure. After considering experimental findings and thermodynamic issues involved with synthesis, ideal reaction system parameters have been identified that promote the creation of a composite with ideal microstructure and formulated composition. Reactive high energy ball milling has been used to create copper matrix composites reinforced with zinc oxide and copper matrix composites reinforced with lead titanate (PbTiO₃). The microstructures and compositions of each volume percentage formulation of the composite powders have been analyzed. In this work, several promising piezoelectric-reinforced metal matrix composite systems have been identified as having potential to be synthesized in an in-situ manner. / Master of Science

Yes / Despite the rising interest in pharmaceutical cocrystals in the past decade, there is a lack of research in the solid processing of cocrystals downstream to crystallization. Mechanical stress induced by unit operations such as milling could affect the integrity of the material. The purpose of this study is to investigate the effect of milling on pharmaceutical cocrystal and compare the performance of ball mill and jet mill, using caffeine-glutaric acid (1:1) cocrystal as the model compound. Our results show that ball milling induced polymorphic transformation from the stable Form II to the metastable Form I; whereas Form II remained intact after jet milling. Jet milling was found to be effective in reducing particle size but ball milling was unable to reduce the particle beyond certain limit even with increasing milling intensity. Heating effect during ball milling was proposed as a possible explanation for the difference in the performance of the two types of mill. The local increase in temperature beyond the polymorphic transformation temperature may lead to the conversion from stable to metastable form. At longer ball milling duration, the local temperature could exceed the melting point of Form I, leading to surface melting and subsequent recrystallization of Form I from the melt and agglomeration of the crystals. The findings in this study have broader implications on the selection of mill and interpretation of milling results for not only pharmaceutical cocrystals but pharmaceutical compounds in general.

No / The oligomerisation of L-amino acids by papain was studied in a mixer ball mill and in a planetary ball mill. The biocatalyst proved stable under the ball milling conditions providing the corresponding oligopeptides in good to excellent yields and with a variable degree of polymerisation. Both parameters were found to be dependent on the reaction conditions and on the nature of the amino acid (specifically on its side-chain size and hydrophobicity). In addition, the chemoenzymatic oligomerisation was demonstrated by utilising twin-screw extrusion technology, which allowed for a scalable continuous process. Finally, the synthesised oligo(L-Leu) 2b proved to be active as a catalyst in the Juliá–Colonna enantioselective epoxidation of chalcone derivatives. / We acknowledge RWTH Aachen University for support by the Distinguished Professorship Program funded by the Excellence Initiative of the German federal and state governments. We kindly acknowledge Marcus Frings and Plamena Staleva for the HPLC analysis of products 4a–c (RWTH Aachen University) and ASEP for the TGA analysis (Queen’s University Belfast). D. E. C. and S. L. J. acknowledge the agency EPSRC, grant no. EP/R019655/1. Part of this work was performed at the Center for Chemical Polymer Technology (CPT) unit of DWI, which was supported by the EU and the federal state of North Rhine-Westphalia (grant EFRE 30 00 883 02).

Orientador: Célia Maria Landi Franco / Banca: Magali Leonel / Banca: Mieko Kimura / Resumo: O tratamento ácido-alcoólico tem sido proposto para modificar a estrutura do grânulo de amido e obter a máxima conversão de amido nativo em amido solúvel. Este amido modificado torna-se frágil quando submetido à moagem em moinho de bola produzindo pequenos cristais que podem ser usados como substitutos de gordura. Neste trabalho, características físico-químicas, estruturais e morfológicas de amidos tratados com ácido-etanol (0,36% HCl em etanol anidro por 1 e 12 h a 30, 40 e 50oC) submetidos ou não a moagem em moinho de bola por 1 h foram analisados e comparados. A recuperação dos amidos foi alta atingindo em média 98%, independente do tempo e temperatura de tratamento. A solubilidade aumentou com o aumento da temperatura e tempo de tratamento e os amidos tratados a 40oC/12h e 50oC/12h tornaram-se totalmente solúveis a 95oC. O tamanho médio dos grânulos de amido de mandioca reduziu com o aumento do tempo e da temperatura de modificação, passando de 25,2 mm para 20,0 mm após 12 h de tratamento a 50oC. A moagem reduziu o tamanho médio dos grânulos de amido nativo e daqueles submetidos a tratamentos ácido-alcoólicos mais brandos (1 h a 30 ou 40oC), enquanto o tamanho médio dos grânulos tratados por 12 h, independente da temperatura, permaneceu inalterado. Os grânulos de amido de mandioca, observados em microscópio eletrônico de varredura, apresentaram forma arredondada e após tratamento com ácido-álcool a 50oC por 12h antes e após moagem, mostraram superfície áspera e rugosa sugerindo erosão com conseqüente solubilização das camadas mais externas dos grânulos. Alguns grânulos mostraramse disformes sugerindo gelatinização parcial que foi mais intensa após moagem. O índice de cristalinidade relativa (IC) dos amidos, determinados por difração de raios- X, aumentou quanto maior o tempo e temperatura de tratamento, enquanto o teor de amilose... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Acid-alcohol treatment has been proposed to modify starch granule structure and obtain maximum conversion of raw starch into soluble starch. Acid-alcohol starch becomes fragile when submitted to the milling in ball mill producing small crystals, which can be used as fat substitute. In this work, physicochemical, structural and morphological characteristics of acid-ethanol cassava starch (0,36% HCl in anhydrous ethanol during 1 and 12 h at 30, 40 e 50oC) followed by milling in ball milling for 1 h were analyzed and compared. The recovery of the modified starches was high reaching 98% independent of time and temperature. The solubility increased with increasing of the treatment temperature and time, and after 1 h at 50ºC the modified starch became totally soluble to 95ºC. The average size of the cassava starch granules decreased with increasing of the treatment time and temperature from 25.2 µm to 20.0 µm after 12 hours of treatment at 50ºC. The milling decreased the average size of the native starch granules and those submitted to milder treatments (1 h at 30 or 40oC), while the average size of the starch granules treated for 12 h, independent of temperature, kept unchanged. From scanning electron microscopy, the native cassava starch granules presented round shape and smooth surface. After acid-ethanol treatment at 50oC for 1h, before and after milling, the granules displayed rough and exfoliated surfaces suggesting erosion with solubilization of the outer layer of the granules. Some granules treated at 50oC during 12 h showed deformed surfaces suggesting partial gelatinization of the starch that was more intense after milling. Relative crystalline index (CI) of the starches, determined from X-ray diffraction, increased with increasing of the treatment time and temperature, while the amylose content, intrinsic viscosity and pasting viscosities decreased... (Complete abstract click electronic access below) / Mestre

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.

The aim of this research was to study the effect of pre-treatment and modification processes on the properties of hemp cellulose fibre for biopolymer composites application. Hemp fibres have been modified by various extraction, swelling, chemical and enzymatic treatments. The morphology and mechanical properties of the modified fibres have been measured. Biopolymer composites have been prepared using the modified fibres and matrices of cellulose acetate butyrate and cellulose solutions derived from hemp. The first fibre treatment employed was acetone extraction and mercerization. A low pressure acrylonitrile grafting initiated by azo-bis-isobutylonitrile was performed using alkali treated fibre. The AN grafted fibres had no transformation of crystalline structure as observed after mercerization. The mechanical properties performed by a single fibre test method were strongly influenced by the cellulose structure, lateral index of crystallinity, and fraction of grafting. Bioscouring of hemp using pectate lyase (EC 4.2.2.2), Scourzyme L, was performed. Greater enzyme concentration and a longer treatment improved the removal of the low methoxy pectin component. Removal of pectate caused no crystalline transformation in the fibres, except for a slight decline in the X-ray crystalline order index. Smooth surfaces and separated fibres were evidence of successful treatment. The shortening of fibre by grinding and ball-milling was introduced to achieve a desired fibre size. An increase in the milling duration gradual ly destroyed the crystalline structure of the cellulose fibres. An increase in solvent polarity, solvent-fibre ratio, agitation speed and drying rate resulted in the rearrangement of the ball-milled cellulose crystalline structure to a greater order. The thermal degradation behaviour of hemp fibres was investigated by using TGA. The greater activation energy of treated hemp fibre compared with untreated fibre represented an increase in purity and improvement of structural order. The all hemp cellulose composites were prepared by an introduction of fibres into 12% cellulose N-methyl-morpholine N-oxide (NMMO) solution and water-ethanol regeneration. A broadening of the scattering of the main crystalline plane, (002) and a depression of the maximum degradation temperature of the fibres were observed. These revealed a structural change in the fibres arising from the preparation. The mechanical properties of composites depended on size, surface area, crystallinity and the structural swelling of the fibres. Composites of cellulose acetate butyrate (CAB) and modified hemp fibres were prepared. Composites containing pectate lyase enzyme treated fibres showed better mechanical property improvement than untreated and alkali treated fibres respectively.