Abstract
The electron spin resonance (ESR) line shape of nitroxide radical labels attached to poly(ethylene oxide) (PEO) chains in a blend with isotactic poly(methyl methacrylate) (PMMA) of higher molecular weight than that in Part I of this series was studied as a function of aging and annealing temperatures. Two spectral components with different rates of motion, a “fast” component and a “slow” component arising from the radicals, are also observed. The fractional amount of the fast component (mobile fraction) observed at 27°C changes with aging and annealing temperatures. The fraction decreases abruptly around −15°C with decreasing aging temperature, whereas the fraction increases abruptly around 50°C with increasing annealing temperature. The specific volume of the blend was measured at 27°C by the dilatometric method. ca. 0.5% of volume contraction and expansion during aging at −15°C and annealing at 50°C, respectively were observed, attributed to relaxation related to free-volume formation and relaxation in an amorphous region of the blend.
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