DIELECTRIC INVESTIGATION OF THE MOLECULAR-DYNAMICS OF BLENDS .2. POLYMERS WITH DISSIMILAR MOLECULAR ARCHITECTURE (PS TMPC BLEND)/

The molecular dynamics of polystyrene/tetramethyl polycarbonate (PS/TM PC) blends were investigated using dielectric spectroscopy in the freq uency and temperature ranges 10(-2)-10(7) Hz and 50-220 degrees C, res pectively. Blends with different compositions, namely 12.5, 25, 50, 75 and 87.5 wt% PS/TMPC were found to be compatible over the entire comp osition range and showed one glass relaxation process corresponding wi th the transition observed by calorimetric measurements. It was found that neither the kinetics. or the distribution of relaxation times of the local process observed in pure TMPC were affected by blending. Thi s fact implies that the local environment of the segments is not chang ed upon blending. Furthermore, these blends showed that the blending o f TMPC with weakly polar polystyrene does not cause any change in the dipolar interaction of the TMPC segments, so that the relaxation stren gth varies linearly with composition. It is concluded that the polymer ic chains of the TMPC and PS are not mixed at a segmental level, but a t a higher structural level lying somewhere between segmental and mole cular. This conclusion is in good agreement with that obtained in the case of blends composed of polymers with similar molecular architectur e.