Use of magnetic resonance imaging to study transport of methanol in poly(methyl methacrylate) at variable temperature

The transport kinetics of methanol in PMMA have been studied over the temperature range 25-60 degrees C, using magnetic resonance imaging. It is shown that transport behavior changes from being relaxation controlled (Case II) at the lowest temperature to approaching Fickian behavior at the higher temperatures. It is also shown that the change of the exponent of time, n, describing the methanol uptake, with the swelling temperature can be compared with a change of the mechanical behavior of the polymer matrix in the presence of the penetrant. From DSC and DMA measurements, it can be concluded that the transition from Case II toward Fickian diffusion takes place at a temperature around the effective T-g of the imbibed material.