DIFFUSION OF MISCIBLE LIQUIDS IN DENSE POLYMERS STUDIED BY MAGNETIC-RESONANCE MICROIMAGING

Magnetic resonance chemical shift microimaging has been used to determ ine the distribution of each liquid absorbed by polymers from mixtures of miscible liquids. Dental 'self-cure' polymethylmethacrylate (PMMA) specimens were immersed in acetone/water and polyester resins in a qu aternary model petrol. Images were recorded periodically. Diffusion pr ofiles of the liquid absorbed by the PMMA were computed from the image s. These profiles suggest that diffusion was Fickian, although the ima ges appeared to show Case II diffusion. In general, polyester resin wa s susceptible to attack by a mixture of two of the petrol components, and absorption, swelling and fragmentation could be followed by magnet ic resonance microimaging.