Photoacoustic spectroscopy applied to glass transition temperature determination of polymers / Aplicação da espectroscopia fotoacústica na determinação da temperatura de transição vítrea de polímeros

AUTOR(ES)

Talita Zanon Guzzo

DATA DE PUBLICAÇÃO

2010

RESUMO

Photoacoustic spectroscopy (PAS) is a non-destructive technique and it has been largely applied to the thermal and optical characterization of materials. PAS technique is based on the photoacoustic effect which consist, basically, absorption of a modulated electromagnetic radiation and generation of heat inside of the material studied (sample), by a nonradiative deexcitation processes. Nowadays, among many PAS applications, effort are carried out to apply PAS technique for second-order phase transitions. However, only a few works can be found in the literature about glass transition studies with PAS technique. In this context, the main goal of this work is to apply PAS technique to determine glass transition temperature of the polymeric materials, based on the new photoacoustic cell configuration and on the new heating system. In this way, a photoacoustic cell was builted up for monitoring temperature variation of the sample, where the performance of the microphone was not affected. A heating system was developed based on the Peltier effect, in such way that it is possible to scan the temperature from the environment one up to 130 C, linearly at several speeds. The experimental apparatus was tested and applied to some polymeric materials: polyamide 6.0 (Nylon); polystyrene (PS-n1921 e PS-n2380); and poli(tereftalato de etileno) (PET). The results obtained were: Nylon, ; PS-n1921, ; PS-n2380, ; and PET, . These results are in a good agreement with the respective values of glass transition temperature found in the literature and show the PAS technique potentiality for glass transition studies in polymeric materials.

ASSUNTO(S)

vidro transformações de fase (física estatística) espectroscopia acústica - ótica engenharia de materiais e metalurgica materials - thermal properties glass transitions temperature transição de fase vítrea glass - phase transitions (statistical physics) photoacoustic spectroscopy caracterização de materiais materials - optical properties materiais propriedades óticas polímeros - transformações de fase (física estatística) optoacoustic spectroscopy espectroscopia fotoacústica polymers - phase transitions (statistical physics) materiais propriedades térmicas materials characterization

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