THE EFFECT OF CARBON-BLACKS AND SURFACE-ACTIVE SUBSTANCES ON THE SYNTHESIS AND PROPERTIES OF POLY(ETHYLENE-TEREPHTHALATE) .3. STUDIES ON THE DISPERSION DEGREE OF CARBON-BLACK AND ON THE CRYSTALLIZATION AND RHEOLOGICAL CHARACTERISTICS OF THE POLYMER

The dispersion degree of a carbon black suspended in ethylene glycol in the presence of surface active substances was determined by microscopic observations and by colorimetry following centrifugation of the suspension. The state of aggregation of the carbon black in the samples of the black-colored polymer was evaluated by optical-microscopic observations of microtomed PET sections. The differential scanning calorimetry method was used to determine the melting point, the glass transition point, the crystallization-onset temperature and the maximum-crystallization-rate temperature of the carbon-black colored samples. The effects of the type of the surface active (ionogenic and non-ionic) substance and of the coloring blacks differing in particle size and the degree of surface oxidation were discussed. The effect of carbon blacks and surface active substances on the theological properties of the colored PET was evaluated by melt flow index measurements.