Calculation of the LVČ (M) relationship for ethylene/propylene copolymers from the relations for homopolymers

Abstract

Relations between the intrinsic viscosity LVČ and the weight-average molecular weight Mw for ethylene-propylene copolymers differing in composition are calculated from the the conformational and interaction parameters for polyethylene and polypropylene using the principles of the two-parameter theory of dilute polymer solution. The interaction parameter between chemically dissimilar monomer units is assumed to be zero. For high-temperature solvents (tetralin, trichlorobenzene and alfa-chloronaphthalene) the relation is found to be sensitive to the copolymer composition. The results of calculations are confronted with experimental results available in literature, and good agreement is obtained. The results are used to theoretically explore the effect of copolymer composition on the calibration of SEC columns.