This paper contains an extensive presentation of dynamic mechanical data (complex moduli), as obtained on the melts of a series of standard polystyrenes of narrow molar mass distributions. It also shows the way of obtaining structural parameters (plateau modulus and friction factor) which are needed for an interpretation of these data in terms of simple theoretical models (Maxwell elements, Doi-Edwards model). A linear mixing rule is used for taking into account the finite width of the molar mass distributions.
Abstract." A mixing rule as suggested by the Doi-Edwards theory is checked experirnentally. For this purpose, the dynamic shear rnoduli as functions of circular frequency are measured first for the melts of a series of polystyrenes of narrow molecular mass distributions. After the careful preparation of mixtures the same moduli are also determined for these mixtures. A discussion is given of the remarkable but limited validity of the additivity of contributions by the single macromolecules to the mentioned moduli.
For the investigated standard polystyrenes possessing narrow molecular mass distributions the choice of an analytical distribution function does not pose serious problems, so that the two-parameter Wesslau function can be chosen for ease in handling. The best values for these parameters as well as for two short range molecular parameters are obtained with the aid of a regression method in which traditional data for the molar mass distribution are improved with the aid of elastico viscous data of high accuracy.
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