Estudo da interação de blenda de policloropreno e borracha natural (PCP/NR) com FeCl3.6H2O em solução

• Ano de defesa: 2010
• Autor(a) principal: Freitas, Adonilson dos Reis
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Departamento de Química; Programa de Pós-Graduação em Química; UEM; Maringá, PR; Centro de Ciências Exatas
• Palavras-chave em Português: Elastoméricos; Policloropreno; Borracha natural; Blendas poliméricas (PCP - NR); Miscibilidade; Polímeros; Degradação; Fotoquímica (Processos); Cinética; Solvente; Processo Foto-Fenton; Brasil.; Polychloroprene; Natural rubber; PCP/NR blend; Miscibility; Polymer degradation; Photo-Fenton process; Degradation kinetic; Solvent effect; Brazil.; Ciências Exatas e da Terra; Química
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/3940

Blends of polychloroprene (PCP) and natural rubber (NR), in liquid solution and in the presence of iron(III) hexahydrate (FeCl3.6H2O), and exposing to polychromatic light were studied in this Thesis. The miscibility of PCP/NR system was evaluated through dissolution solution viscometry (DSV) and through visual observation. The PCP/NR degradation was studied by normalized efflux time measurements, using an Ubbelohde capillary viscometer. The influence of temperature, exposing or not polychromatic to light and total polymer concentration on the efflux time were analyzed using a 23 full factorial design. The degradation process was also characterized by Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (1H RMN), Gas Chromatography coupled to Mass Spectrometry (GC-MS) and Thermogravimetric Analysis (TGA). The influence of solvent and their properties on the degradation process were also investigated. The results showed that mixture of PCP and NR in a common solvent separates in two phases. Also, the DSV data confirmed that PCP and NR are immiscible at any ratio. The factorial design showed that temperature does not influence the degradation process. On the other hand, the exposure to light and the concentration of polymer as well as their combination have been identified as important inputs for the degradation process of both components of the blend. Efflux time data showed that small amounts of PCP in the blends PC/NR accentuates the degradation of NR. We proposed a second order kinetic model that fits the data well viscometric especially when the polymer concentration and light are studied at higher levels (22.7 mg / mL and exposure to polychromatic light). Still, it was found that altering the proportion of components in the blend there is no significant change in the results of the factorial design. Spectral changes on FTIR and 1H NMR spectra due to degradation process, such as the appearance of new bands or disappearance of other were verified. The profile of fragmentation of the residues found in the blend solution PCP/NR-FeCl3.6H2O obtained by GC-MS suggest a recombination among the degradation products of PCP with the NR. Thermograms pointed out the formation of degradation products less thermally stable than the virgin polymers to blend. It was also verified through efflux time data that the solvent as well as their properties such as dielectric constant, dipole and surface tension play important role in the degradation process. Thus, the properties of solvents enhance or reduce the degradation effect. In this sense, it was found that both PCP and PCP/NR degrade, but from the kinetic point of view the process is dependent of: i) the reaction time, ii) with the solvent. This work opens new perspectives in the study of polymer degradation especially elastomers such as natural rubber and polychloroprene.