Herramientas de Accesibilidad
SOUSA, F. V. V.; BARCIA, O. E.; QUINTELA, J. P.; MARGARIT-MATTOS, I. C. P. (2023).
Resumo: O uso de tintas de isolamento térmico (TIT) para eficiência de energia e proteção pessoal vem aumentando, pois esta tecnologia propõe benefícios em comparação com os isolamentos convencionais, como maior facilidade de aplicação e manutenção, uso em espessuras menores e prevenção de corrosão sob isolamento (CUI).
O objetivo deste trabalho é discutir aspectos relacionados à condutividade térmica, propriedades anticorrosivas e influência do envelhecimento nessas propriedades, com base em testes laboratoriais de duas TITs comerciais — uma com tecnologia acrílica e outra epóxi.
GROSSO, MARCELLA ; BURROWES, M. ; KOTIK, H. G. ; CAMERINI, C. G. ; DALMEIDA, A. F. ; PEREIRA, G. R. (2023).
Resumo: his paper evaluates the tensile properties in the axial direction of GFRP pipes aged under high pressure (73 and 89 bar) and high temperatures (60°C and 93°C) through time. The tests were performed according to ASTM D3039-17. The modulus of elasticity showed the highest degradation compared to the condition without aging. The aging affected the tensile modulus of elasticity much more significantly than the tensile strength. The aging conditions at 89 bar were the most aggressive, generating macroscopic delaminations and the greatest losses in tensile properties.
SILVA, ELAINE F.; Luciene S. Santos ; BANDEIRA, MERLIN C. E. ; MATTOS, OSCAR R. ; Nara G. Berry ; Sylvia C. S. Teixeira ; Antônio H. M. F. T. Silva ; Erica G. Chaves. (2023).
Resumo: The recommended standard technique for monitoring the degradation of polyamide 12 (PA-12) is viscosimetry, through measurements of inherent viscosity (IV) to obtain the values of Corrected Inherent Viscosity (CIV). The CIV values were used as reference to correlate with Raman and IR results. PA-12 pristine samples and those submitted to ageing in reactors with controlled pressure and supercritical CO2 conditions were analyzed. The specimens were immersed in mineral water (pH 4.0), at a temperature of 120 °C for a period of up to 45 days. From the Raman spectra the νasCH2 vibration at 2924 cm– 1 seems to be a sensitive spectral probe of PA-12 hydrolytic degradation, therefore the relative intensity decrease of pristine and aged samples was used to compare RAMAN and CIV results. From FTIR spectra, a variation in the intensity of the bands attributed to the α and γ phases, at ~ 1560 and 1545 cm– 1, respectively, was observed, which might be related to the degradation/ageing of the polymer. After analyzing samples submitted to different ageing conditions, there are good evidences that an analyses protocol of Raman and FTIR give consistent qualitative information on the degradation of PA-12, and therefore, is a new alternative for monitoring the hydrolytic degradation of PA-12, thus eliminating the use of toxic organic solvents, reducing the analysis time and bringing information about the degradation mechanism.
Elaine F. Silva, Ph.D.; Julio S. Wysard, M.Sc., Chemistry; Tatiana C. Almeida; Merlin C. E. Bandeira, Ph.D., Materials Science; Oscar R. Mattos. (2023).
Resumo: Adsorption of imidazole, 4-methylimidazole and guanine on copper in chloride solutions was investigated by a combination of weight loss tests with electrochemical and Raman techniques to understand their inhibition efficiency and interaction with the metal. Results revealed that imidazole and 4-methyimidazole are inefficient while guanine was an efficient inhibitor (86 %) due to formation of a passive film. Guanine was not efficient towards API 5L X65 steel corrosion in HCl (~22 %) and the low efficiency was due to physisorption. The insights obtained with the combination of spectroscopic and electrochemical results should aid selecting new efficient nontoxic inhibitors.
SILVA, V. M. A. ; CAMPO, L. B. ; CAMERINI, CESAR G. ; PEREIRA, G. R. (2023).
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