1995 Volume 23 Issue 1 Pages 13-19
The complex Young's modulus, E* (ω), and the complex strain-optical coefficient, O* (ω), were simultaneously determined at various temperatures (T) covering from the rubbery to the glassy zone for a series of alkyl methacrylates, poly (methyl, ethyl, n-butyl, and n-hexyl methacrylate). At T above the glass-to-rubber transition temperature, T<TUB>g</TUB>, all samples exhibited a negative peak in the imaginary part of O* (ω) at 2 H<TUB>z</TUB>, O″(ω). The negative peak appeared to be related to polymer chain orientation. At lower T near T<TUB>g</TUB>, a positive O″ peak corresponding to the α dispersion was observed. For the four samples the magnitudes of those negative and positive peaks decreased and increased, respectively, with increasing length of the alkyl-group. With further decreasing T below T<TUB>g</TUB>, the methyl and ethyl esters again exhibited a negative O″ peak, that was attributed to the β dispersion as judged from viscoelastic data.