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.
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