VISCOELASTIC PROPERTIES OF HIGH MOLECULAR-WEIGHT POLYMERS IN THE MOLTEN STATE .2. INFLUENCE OF THE MOLECULAR-WEIGHT DISTRIBUTION ON LINEAR VISCOELASTIC PROPERTIES

The effect of the molecular-weight distribution on linear viscoelastic properties is studied in the case of atactic polystyrene. First, the prediction of the linear behavior is made from an analytical expression of the complex compliance J* (ω), in a broad frequency range (8 decades). We then deduct the properties of binary blends, using a blending law on the complex modulus G* (ω). We extend at last this blending law to the case of a continuous distribution of molecular weights. The agreement with experimental data was found satisfactory, provided the molecular-weight distribution is known with a good precision, and the low-molecularweight tail (M < Mc) is negligible. © 1979 Dr. Dietrich Steinkopff Verlag.