On Interconversion of Various Material Functions of PMMA

Abstract

The interconversion between various linear viscoelastic functions forPoly (methyl) methacrylate (PMMA) is explored. With the availability offour time or frequency-dependent material functions (shear, bulk,uniaxial and Poisson) on the same material, various material functionsare computed using the correspondence principle of the linearized theoryof viscoelasticity through the use of standard relations. Computedmaterial functions are evaluated against the directly measuredproperties and the limitations imposed on successful interconversion dueto the experimental errors in the underlying physical data are explored.It is observed that the differences between the computed and measuredfunctions were larger than suggested by experimental error. The resultsintimates the need to thoroughly re-examine the applicability oftime-temperature superposition principle often employed to develop`master curves' for viscoelastic functions, especially with respect tothe glassy domain.