Interdiffusion of PMMA and PVF2, studied by solid-state NMR.
A previous published new solid-state NMR method is applied to the interdiffusion of poly(Me methacrylate) (PMMA) and poly(vinylidene fluoride) (PVF2) above their glass temps. Via a variation of the cross-polarization techniques, magnetization is transferred from protons to fluorines. When this magnetization is made to disappear at the fluorine sites, only those protons that are distant from fluorines greater than the distance over which cross-polarization functions will retain their magnetization. In this way, the authors detect the fraction of PMMA near (ca. 20 .ANG.) PVF2. Starting from sheets of PMMA and PVF2, which are then heated at 190 Deg for a variable time, and applying the above technique, the authors can det. the fractions of PMMA and PVF2 that have diffused within a distance of a few .ANG. of each other. The intrinsic diffusion coeffs. of PMMA and PVF2 detd. from such expts. compare well with literature data. Initial attempts to fit the exptl. data suggest that the concn. dependence of the diffusion coeffs. cannot be neglected.
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