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Otimização dos Sistemas de Conservação nas Emulsões Aquosas
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O presente estudo integrou-se num estágio realizado no laboratório de investigação e desenvolvimento (LID) da empresa Synthomer. Esta dissertação teve como objetivo otimizar o sistema de conservação em quatro emulsões aquosas. Para esse efeito estudou-se os vários fatores que influenciam a estabilidade dos sistemas de conservação, utilizando o Desenho de Experiências (DOE) e, em paralelo, controlou-se os parâmetros da qualidade para se obter um produto conforme.
Tendo em vista a nova legislação permitida para as isotiazolinonas (principalmente, para BIT e a combinação de CIT/MIT), um dos grupos de biocidas mais utilizados na preservação das emulsões aquosas que inibem o crescimento de vários microrganismos, pretendeu-se maximizar a sua quantidade em cada produto.
Primeiro foram selecionados os fatores a variar (tipo e quantidade de redutor, temperatura de adição do par redox e etapa da neutralização) nas emulsões. Com o auxílio do DOE estudou-se a melhor combinação que levasse à menor degradação dos biocidas. Em paralelo, analisou-se as propriedades finais, focando o pH e o potencial redox como parâmetros que poderiam influenciar a estabilidade dos biocidas. Por fim, fez-se um Estudo de Estabilidade para averiguar o comportamento de cada emulsão ao longo do tempo nos ensaios gerados pelo DOE e iniciou-se o mesmo estudo para um novo sistema de conservação para os mesmos produtos estudados.
Conclui-se que para cada produto a combinação escolhida otimizou o sistema de conservação (diminuiu a degradação) e manteve os parâmetros de controlo de qualidade dentro dos limites teóricos. Os biocidas nos copolímeros vinílicos um e dois degradaram-se 14% (-3%da referência) e 15% (-23% da referência) para BIT e 16% (-1% da referência) e 20% (-12% da referência) para CIT/MIT, respetivamente. No copolímero estireno-acrílico os biocidas degradaram-se 13% (-62% da referência) para BIT e 8% (+4% da referência) para CIT/MIT e no copolímero acrílico puro o biocida BIT degradou-se 3% (+1% da referência) e 10% (-4% da referência) para o biocida CIT/MIT.
Estes valores indicam que as emulsões aquosas apresentadas estarão protegidas contra possíveis contaminações microbiológicas no armazenamento ou contra subprodutos que reajam com os conservantes. Em súmula, comprova a estabilidade dos biocidas em cada uma das combinações geradas, principalmente no copolímero vinílico dois e no estireno-acrílico.
The present study was part of an internship carried out in the research and development laboratory (LID) of the company Synthomer. The objective of this dissertation was to optimize the conservation system in four aqueous emulsions. For this purpose, several factors that influence the stability of conservation systems were studied using the Design of Experiments (DOE) and, in parallel, the quality parameters were controlled to obtain a compliant product. In light of the new legislation permitted for isothiazolinones (for BIT and the combination of CIT/MIT), one of the groups of biocides most used in the preservation of aqueous emulsions that inhibit the growth of various microorganisms, the aim was to maximize their quantity in each product. First, the factors to vary (type and amount of reductant, redox couple addition temperature and neutralization step) in the emulsions were selected. With the help of the DOE, the best combinations that would lead to the least degradation of biocides were studied. In parallel, the final properties were analysed, focusing on pH and redox potential as parameters that could influence the stability of biocides. Finally, a Stability Study was carried out on the tests generated by the DOE to investigate the behaviour of each emulsion as time goes by and also the same study began for a new preservative system for the same products studied. It is concluded that for each product the chosen combination optimized the conservation system (reduced degradation) and maintained quality control parameters within theoretical limits. The biocides in vinyl copolymers one and two degraded 14% (-3% of the reference) and 15% (-23% of the reference) for BIT and 16% (-1% of the reference) and 20% (-12% of the reference) for CIT/MIT, respectively. In the styrene-acrylic copolymer the biocides degraded 13% (-62% of the reference) for BIT and 8% (+4% of the reference) for CIT/MIT and in the pure acrylic copolymer the BIT biocide degraded 3% (+ 1% of the reference) and 10% (-4% of the reference) for the CIT/MIT biocide. These values indicate that the aqueous emulsions presented will be protected against possible microbiological contamination during storage or against by-products that react with the preservatives. Summarizing, it proves the stability of biocides in each of the combinations generated, mostly in vinyl copolymer two and in styrene-acrylic.
The present study was part of an internship carried out in the research and development laboratory (LID) of the company Synthomer. The objective of this dissertation was to optimize the conservation system in four aqueous emulsions. For this purpose, several factors that influence the stability of conservation systems were studied using the Design of Experiments (DOE) and, in parallel, the quality parameters were controlled to obtain a compliant product. In light of the new legislation permitted for isothiazolinones (for BIT and the combination of CIT/MIT), one of the groups of biocides most used in the preservation of aqueous emulsions that inhibit the growth of various microorganisms, the aim was to maximize their quantity in each product. First, the factors to vary (type and amount of reductant, redox couple addition temperature and neutralization step) in the emulsions were selected. With the help of the DOE, the best combinations that would lead to the least degradation of biocides were studied. In parallel, the final properties were analysed, focusing on pH and redox potential as parameters that could influence the stability of biocides. Finally, a Stability Study was carried out on the tests generated by the DOE to investigate the behaviour of each emulsion as time goes by and also the same study began for a new preservative system for the same products studied. It is concluded that for each product the chosen combination optimized the conservation system (reduced degradation) and maintained quality control parameters within theoretical limits. The biocides in vinyl copolymers one and two degraded 14% (-3% of the reference) and 15% (-23% of the reference) for BIT and 16% (-1% of the reference) and 20% (-12% of the reference) for CIT/MIT, respectively. In the styrene-acrylic copolymer the biocides degraded 13% (-62% of the reference) for BIT and 8% (+4% of the reference) for CIT/MIT and in the pure acrylic copolymer the BIT biocide degraded 3% (+ 1% of the reference) and 10% (-4% of the reference) for the CIT/MIT biocide. These values indicate that the aqueous emulsions presented will be protected against possible microbiological contamination during storage or against by-products that react with the preservatives. Summarizing, it proves the stability of biocides in each of the combinations generated, mostly in vinyl copolymer two and in styrene-acrylic.
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Palavras-chave
Biocidas Degradação Desenho de Experiências Emulsão Aquosa Estudo de Estabilidade Otimizar