DIELECTRIC STUDIES OF SPECIFIC INTERACTION AND MOLECULAR-MOTION IN SINGLE-PHASE MIXTURE OF POLY(METHYL METHACRYLATE) AND POLY(VINYLIDENE FLUORIDE)

It is well known that the miscibility of dissimilar polymers with high molecular weights arises from specific interaction, such as hydrogen bonding. To discuss the influence of the interaction on a side group r otation and main chain motion of poly(methyl methacrylate) (PMMA) in P MMA/poly(vinylidene fluoride) (PVDF;) blends, we investigated the diel ectric loss epsilon '' as a function of frequency f. epsilon ''(f) sho wed a peak at around 10(4) Hz, which is assigned to the beta process c haracteristic of the side group rotation of PMMA below the glass trans ition temperature (T-g) and the alpha beta process characteristic of t he side group rotation cooperative with the main chain motion above T- g. Above T-g, the peak frequency f(max) increased and then decreased w ith increasing PVDF content (phi); f(max)(phi) showed a peak at phi ap proximate to 10 wt.%. The increase may be interpreted by the accelerat ion of main chain motion by lowering of T-g with increasing the conten t of the lower T-g component (PVDF). Increasing further the PVDF conte nt, the specific interaction seems to restrict the main chain motion a nd prevails over the T-g effect so that the peak appears in the f(max) (phi) curve. f(max) decreased with increasing annealing time t(a), sug gesting the increase in restriction with t(a). This may imply that the association of dissimilar polymers by the specific interaction is a v ery slow rate process on a time scale of thousand minutes. Also observ ed after annealing were broadening of the relaxation time distribution and the appearance of interfacial polarization, suggesting a change i n chain conformation from random coil to a locally stretched state to form a nematic domain. (C) 1997 Elsevier Science Ltd.