Quasi-Isochronal Viscoelastic Measurements

When measurements are made at approximately constant frequency on plasticized polymers over a range of temperatures, the location of the transition zone naturally shifts to lower temperatures with increasing dilution. It is difficult to find examples for uncross-linked polymers, because most experimental methods are not adapted to the fluid systems obtained at higher dilutions. However, the pattern 

Loss tangents of lightly cross-linked polystyrene swollen to various extents in dibuiyl phthalate, plotted against temperature at a frequency of I Hz. Numbers denote polymer concentration in weight percent. (Illers and Jenekel. ) 

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