Jato de plasma frio em pressão atmosférica para tratamento de materiais e esterilização

• Ano de defesa: 2015
• Autor(a) principal: Nishime, Thalita Mayumi Castaldelli [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Polímeros; Jato de plasma; Esterilização; Superfícies (Física)
• Link de acesso: http://hdl.handle.net/11449/132036; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/09-12-2015/000855445.pdf

Atmospheric pressure plasma jets (APPJs) are capable of generating cold plasma in open environment. The gas flow from the jet carries the plasma to the outside region. Because of its enhanced chemistry and ability of treating 3D objects, APPJs are suitable for applications in many fields of industry and technology. In this work, two different applications of plasma jets were investigated. In the first part, a corona-like plasma jet was used for surface treatment of two polymers, the polypropylene (PP) and the polyethylene terephthalate (PET). The jet was operated with helium and argon gas. The aims of this study are to evaluate the formation of low-molecular-weight oxidized material (LMWOM) on the polymers surface and to determine the optimal treatment conditions. The changes in surface hydrophilicity, chemical composition of polymers surface and the material roughness were analyzed. The results show that the LMWOM formed due to the plasma exposure tends to agglomerate into small mounts on the surface. These structures are weakly bounded to the surface and can be easily removed by rinsing in polar solvents. After washing the treated samples, the polymers partially recover their original wetting characteristics. The jet-to-sample distance was found to be an important parameter that can significantly influence the treatment uniformity. In the second part of this work, a DBD-type plasma jet working in helium was applied for inactivation of microorganisms. The effectiveness of the APPJ was evaluated against three common pathogenic agents, the Gram-positive bacteria Enterococcus faecalis (ATCC 29212), the Gram-negative bacteria Pseudomonas aeruginosa (ATCC 15442) and the yeast Candida albicans (SC 5314). The effect of plasma treatment was evaluated by measuring the inactivation zone diameter. The cell morphological changes were analyzed using scanning ...(Complete abstract click electronic access below)