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Polímeros

versão impressa ISSN 0104-1428versão On-line ISSN 1678-5169

Resumo

SALES, Rita de Cássia M.  e  DIBBERN-BRUNELLI, Deborah. Hygrothermal effect in glass fiber/epoxy by luminescence spectroscopy. Polímeros [online]. 2008, vol.18, n.1, pp.52-56. ISSN 1678-5169.  http://dx.doi.org/10.1590/S0104-14282008000100011.

The work is aimed at studying hygrothermal effects on uncured glass-epoxy fiber prepreg (F-161 - Hexcel Co.) using luminescence spectroscopy under steady-state conditions. The fluorescence extrinsic method was employed using the 9-anthroic acid probe, whose photophysical behavior is strongly dependent on the polarity of the medium. The samples were submitted to relative humidity of 6 and 84% using saturated aqueous solutions of NaOH at 34.5 °C and KCl at 20.0 °C in closed recipients, for periods of time of 1 week, 15 days and 1 month. The samples submitted to the relative humidity of 6% showed a significant increase in the relative intensity of the fluorescence spectra in relation to the reference sample. This photophysical behavior was attributed to the 9-AA protonated form in the medium due to the polymeric matrix cross-linking process. After 1 month, the emission spectrum showed a decreased maximum intensity, which could be related to the polymeric matrix plasticization caused by water absorption, which was confirmed by gravimetric analysis. The extrinsic fluorescence spectra of the samples submitted to relative humidity of 84% showed the following spectral modifications: a) emission intensity decrease in curves b and d; b) blue shift in the emission band due to the humidity content; e c) appearance of a shoulder in the emission band at 424 and 472 nm. This photophysical behavior was attributed to the chemical equilibrium between protonated and ionized forms of 9-AA in the medium, promoted by absorption of water in the material.

Palavras-chave : Luminescence spectroscopy; hygrothermal effect; prepreg; 9-anthroic acid.

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