EFFECT OF METHOD OF PREPARATION ON MOLECULAR PACKING OF TMPC PS BLENDS/

Dielectric and differential scanning calorimetry measurements of polys tyrene/tetramethyl polycarbonate (PS/TMPC) blends have been carried ou t for two series of samples prepared by a melt mixing method, using a Brabender, and a solvent casting method using methylene chloride. The dielectric measurements of the samples were carried out over wide rang es of temperature (50-220 degrees C) and frequency (10(-2)-10(5)Hz). T he composition ratios of the samples measured were 12.5, 25, 50, 75 an d 87.5 wt% TMPC for solvent casting and 10, 25, 40, 50 and 60 wt% TMPC for melt mixing. It has been found that melt mixing under the conditi ons used produces compatible blends for all the composition ratios mea sured without causing any pronounced degradation. The glass transition temperatures and dielectric relaxation behaviour of the blends prepar ed by the different methods showed differences in molecular packing an d dynamics. The results obtained could be attributed to a variation in the size of structural units responsible for compatibility, which dep ended on the method of preparation.