Structure and rheological properties of polymer mixtures

Abstract

SynopsisInvestigations 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. I t 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.In recent years there has been a steadily growing interest in polymer mixtures. This interest is due to the fact that there is no simpler, more accessible, and sometimes more effective way of modifying the properties of polymers than by mixing two or more of them. The properties of the mixture change slowly within certain limits, depending on the composition of the solid dispersion system. Sometimes, however, the mixtures reveal properties which none of the components possesses. The wide application of polymer mixtures has been achieved so far along practical lines. It is still not known what connection there is among the properties, structure, and composition of the mixtures. Furthermore, an investigation of polymer mixtures should permit us to broaden and supplement the data we have on individual polymers. They are highly convenient models for the purpose.Of greatest interest are the systems composed of amorphous and crystallizing polymers. These are characterized by two opposing trends: the crystal formation of the crystallizing components, on the one hand, and the formation of an amorphous solution between the components, on the 4197

The effect of mixing on the modes of dispersion and rheological properties of two‐phase polymer blends in extrusion

“…In other words, comparison of Figure 13 and It should be mentioned that similar observations have also been reported by other investigators. [13][14][15] Measurements of wall normal stresses were also taken with polymer blends prepared in a twin-screw compounding machine. Figure 14 gives plots of viscosity versus blending ratio, and Figure 15 gives plots of first normal stress differences versus blending ratio for three such blends.…”

Morphology, doping, and electrical properties of poly(p-phenylenevinylene)/poly(ethylene oxide) blends

“…Although large melting point depressions are usually characteristic of miscible systems, this behavior has also been observed in a number of immiscible crys- talline polymer blends and is attributed to a reduction in the average crystalline size as a result of blending. 16,17 The measured enthalpy of melting, AH, for each of the blends has been related to the degree of crystallinity of the PEO component by using the relation AH = XcXPmAH0…”

Investigation of Rheological Behavior of Modified Polychloroprene Adhesive Compositions

“…La prepararea adezivilor prin adãugarea soluþiei de rãºinã, rãºina acþioneazã ca un plastifiant structural intermediar (adicã PHL2) care este poziþionat între structurile supramoleculare ale cauciucului cloroprenic. Sub influenþa unor forþe mecanice, rãºina este capabilã sã pãtrundã între macromoleculele de cauciuc în timpul procesului de amestecare pe valþ, cu rol de plastifiant structural intern (PHL5) [7,30,31].…”

“…PHL2) which is positioned between the over-molecule structures of the chloroprene rubber. Under the influence of mechanical forces the resin is able to enter between the macromolecules of the rubber during the mixing process on the rolls, playing the role of internal structural plasticizer (PHL5) [7,30,31].…”