Utilização de técnicas espectroscópicas e análise térmica no monitoramento da degradação da poliamida 11 utilizada em dutos flexíveis

• Ano de defesa: 2011
• Autor(a) principal: Domingos, Eloilson
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Química; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Química
• Palavras-chave em Português: Polímeros; Fontes de infravermelho; Espectroscopia de raio X; Química; 54
• Link de acesso: http://repositorio.ufes.br/handle/10/4669

In this work, the potential of the techniques of X-ray fluorescence (XRF) spectroscopy, FTIR with infrared spectroscopy with attenuated total reflection accessory and thermal analysis (DSC and DMA) were evaluated for monitoring the degradation of polyamide 11 (PA-11) used in flexible pipes. The samples were subjected to aging on reactors with controlled pressure and inert atmosphere. The samples were immersed in deionized water (pH 7) at temperatures of 110, 120 and 140 ° C over a period of up to 50 days. . The recommended technique for monitoring the degradation of PA-11 is the viscometry, using measures of inherent viscosity corrected (VIC) and thermogravimetric analysis (TGA). The behaviorobserved in the TGA and VIC during aging allowed the construction of models that relate the XRF techniques, FTIR-ATR, DSC and DMA with the degradation suffered by the polymer. The results of TGA showed a decrease in the concentration of plasticizer (n-butyl-benzenosulfonamide) as a function of time, which was monitored by the intensity of the peak assigned to sulfur in the spectrum of XRF. The changes correlated with the decrease in amorphous phase and increase of the crystalline phase in the polymer matrix are directly correlated with changes in mechanical properties of PA-11. From the results of FTIR-ATR, the variation in the intensity of the bands assigned to crystalline and amorphous phases of polymer, 937 and 1161 cm-1 respectively, enabled the monitoring of aging. The thermal data were treated together, and had results that were not perceived by the other techniques, such as oligomers formed within the matrix of PA-11 and variations in glass transition temperature of the polymer. The classification byPCA, and the models generated by PLS and LDA methods were satisfactory in predicting the aging of the PA-11, where the correlation coefficients for XRF techniques, thermal and FTIR-ATR were 0.9035, 0.8185 and 0.7640 respectively, as the results of LDA hadthe proportions of hits 0.808, 0.944 and 0.971 respectively. The techniques explored were efficient to monitor the properties of the polymer, which are directly related to the process of degradation of PA11. These techniques eliminate the use of toxic organic solvents and allow a shorter time of analysis, as is the case of XRF and FTIR-ATR.