Viscosity—Molecular Weight Dependence for Short Chain Polystyrenes

Abstract

Data on the viscosity coefficient 7J in the limit of zero shear on binary polystyrene mixtures having identical number average chain length Z" (hence identical density) but different weight average Z .. establishes that 7J"'Z", when Zw<630 chain atoms, confirming the theory of Bueche for the viscosity of short polymer chains. Strong support for Bueche's theoretical equation, is provided by the successful quantitative prediction of the observed value of 7J from the independently measured values of the unperturbed reduced mean-square radius of gyration of the polymer coil (so')A,IM, of the specific volume v, the friction coefficient per chain atom I, and Avogadro's number, No. Application of this equation now permits ready evaluation of I from viscosity measurements on short chain polymers.

“Fracture” phenomena in shearing flow of viscous liquids

“…Because of the strong temperature-sensitivity of the viscosities of these liquids in the temperature ranges of interest, the viscosities reported here probably have an accuracy of no greater than a factor of two or so. Errors are not likely to be much larger than this, since the viscosity reported here for PS13K is consistent with that measured on a polystyrene of almost identical molecular weight (13 300) by Allen and Fox (1964), who used a capillary viscometer with much better temperature control than we could obtain. In addition, we shall see that the critical stresses for "fracture" are not so temperature sensitive, and are therefore more accurate than the viscosity values.…”

The chain length dependence of self-diffusion in melts of polyethylene and polystyrene

“…However, the parameters for polystyrene are not far from those determined from viscosity, e.g. by Allen and Fox [24], and the free volume corrections for polyethylene are only small, therefore uncertainties in its free volume parameters are of minor effect.…”

NMR field-cycling relaxation spectroscopy, transverse NMR relaxation, self-diffusion and zero-shear viscosity: Defect diffusion and reptation in non-glassy amorphous polymers

“…The power laws below M c must be considered to represent average molecular weight dependences 8 ~/ // ~ calc. from directly measured nmr data (PS [66]; PE [60], [64], (this work) [73], [74] So far, we have derived formulae for diverse observables from the same basis, given by the three-component description of chain fluctuations. However, nuclear magnetic relaxation times depend on more components than zero-shear viscosity does.…”

“…(23b) and (38) and section 11) the proportionality 11 ~ M follows. (Here we have assumed constant free volume properties [61], [66].) Thus equation (43) leads to the semi-empirical formula…”