Effects of Isothermal Volume Changes on Shear and Elongational Relaxation Processes

Effects of Isothermal Volume Changes on Shear and Elongational Relaxation Processes 

Data for G measured at various temperatures and elapsed times did not reduce satisfactorily in this manner, however for/ 0.022, deviations appeared indicating a slight change in the shape of the relaxation spectrum, to which G is more sensitive in this region then G. The magnitude of the deviation appeared to be a single-valued function of/, for all temperatures and elapsed times. 

Measurement of viscoelastic properties as a function of elapsed time following 

Storage shear modulus plotted against logarithm of radian frequency for poly(vinyl acetate) after sudden quench from 45° to 20° or 30°, at different elapsed times in minutes as indicated by numbers at left. Heavy curves refer to measurements at voluminal equilibrium (after completion of isothermal contraction) at the temperatures indicated at right.  

Similar results have been observed in oscillatory measurements on poly(/i-butyl methacrylate).  

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