A series of ethylene vinyl acetate (EVA) copolymers was studied by dynamic mechanical spectroscopy to understand the relative influence of composition, structure, and molecular weight distribution on their rheological behavior in the melt. The examination of their viscoelastic properties in a large temperature range showed that the glass transition temperature is nearly independent on their composition because of the statistical nature of the copolymers, though some long sequence of polyethylene homopolymer may exist at low vinyl acetate (VA) content. The successful use of the time temperature superposition for oscillatory experiments in the melt confirmed the previous remarks, because the application of the Williams Landel Ferry (WLF) equation leads to a unique set of WLF coefficient, whatever the composition of the EVA. This enables the comparison of the rheological behavior in the melt at the same temperature, in the same free volume condition, and at last it was shown that in the terminal zone, the molecular weight distribution is more influent on the behavior of EVA copolymers than their composition.

No abstract

No abstract

No abstract

No abstract

No abstract

The relationship between copolymer composition, molecular weight distribution, and rheological properties of random styrene acrylonitrile copolymers synthesized by radical polymerization in bulk was investigated. From differential scanning calorimetry analysis, glass transition temperature was obtained and increases with the acrylonitrile content. The knowledge of the glass transition is a key factor to compare the different copolymers in an iso‐free volume condition for melt rheology. Owing to time temperature superposition, a large frequencies window ranging from the terminal zone until the glassy plateau can be obtained. Thus, the mechanical spectroscopy was used to estimate the rubbery plateau modulus and the Newtonian viscosity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1316–1321, 2000

No abstract