Structure and rheological properties of polymer mixtures

Investigations were undertaken of the structure and rheological properties of mixtures consisting of one crystallizing and one amorphous polymers. It was established that mixtures of poly(ethylene adipate) and poly(vinyl acetate); of poly(ethylene adipate) and poly(methyl methacrylate); and of poly(ethylene sebacinate) and poly(methyl methacrylate) can form amorphous solid solutions with one another or can crystallize without any apparent division of the two components. The phase condition of the mixture is determined by the nature of the two polymers, by the ratio between them, and by their molecular weights. The melting point of these mixtures drops in proportion to the content of the amorphous component. The assumption is made on the basis of the results obtained that the amorphous component occupies the defective areas in the crystal grating. The fluidity of the mixtures was measured by means of a capillary viscosimeter. It was established in all cases that there appear deviations from the proportional change of the effective viscosity between the viscosities of the components. These deviations are explained by the change in the energy of activation of the viscous flow of the melts which was also subject to determination.