β-Relaxation in polymethylacrylate studied by light scattering |
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Authors: | D. Fioretto A. Livi P. A. Rolla G. Socino L. Verdini |
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Affiliation: | (1) Dipartimento di Fisica dell'Università, Via A. Pascoli, 06100 Perugia, Italy;(2) Dipartimento di Fisica dell'Università, Piazza Torricelli 2, 56100 Pisa, Italy |
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Abstract: | Summary The relaxation processes of glass-forming polymethylacrylate have been studied in a wide temperature range above the glass transition temperatureT g by means of light scattering measurements. Experimental spectra give evidence of a self-similar behaviourI(ω) ∝ ω−(1−a) over a spectral range of 2–3 decades, consistent with the predictions of the mode-coupling theory. Different from the prediction of the theory, the value ofa is strongly temperature dependent. This behaviour has been attributed to the presence of a slow secondary relaxation located in the GHz frequency region, whose strength progressively increases with temperature. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. |
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Keywords: | Glass transitions |
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