Uso da RMN no estudo da despolimerização de poliuretano rígido

• Autor(a) principal: Maioli, Juliana Proliciano
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/11272
• topic: Glycolysis; Glycerol; Glicólise; Glicerol; Química; Poliuretanas; Ressonância magnética nuclear; 54

Polyurethanes (PUs) have been widely used in several trade sections. Thereby, large amounts of waste are produced and need to be correctly disposed off. Research on this theme has been helping industries to apply recycling processes that are cheap and efficient. In this work, the glycolysis of a rigid PU was performed using different catalysts. The catalysts used was: a tensoactive (CTAB), the NaOH, two ionics liquids (1-butyl-3-methylimidazole trichloromanganate and 1-butyl-3-methylimidazole trichlorozincate), and four Niobium salts (niobium pentoxide, niobium oxidehydrated, niobium pentachloride and niobium ammoniacal oxalate). 1H NMR technique was used to obtain the rate of PU depolymerization. Also was used the technique diffusion ordered spectroscopy 1H NMR (DOSY-NMR) that assisted in the identification composition of the mixture of products. In the glycolysis, glycerol (GCL) and diethylene glycol (DEG) were tested as glycolysis agents. The PU was synthesized to be free of additives in the depolymerization process, and its characterization was performed using infrared spectroscopy (FTIR) and 1H NMR spectroscopy analyses. The conversion rate provides information about which catalyst has the better catalytic activity. The use of NaOH as a catalyst presented conversion rate of 100 % in 30 min of reaction, as is already known in the literature, and the DOSY-NMR spectrum provided information about products that didn’t perceptible only by 1H NMR spectrum. Ionic liquids (LIs) as catalysts, presented conversion near of 80 % in 1h of reaction, which can be improved by modifying the reaction conditions. To determine the composition of the mixture of products in the depolymerization reaction, diffusion ordered spectroscopy 1H NMR (DOSY-NMR) was used. The Niobium salts had non-catalytic behavior, because they showed conversion rate lower than uncatalyzed reaction. DOSY-NMR indicated a complex mixture of reaction by-products, differently from the 1H NMR data, which indicated the formation of a simple diamine-terminated by-product.