Dynamic mechanical analysis and dynamic infrared linear dichroism study of the frequency-dependent viscoelastic behavior of a poly(ester urethane)

Dynamic infrared linear dichroism (DIRLD) data have been collected as a function of strain modulation frequency in a simultaneous DIRLD-dynamic mechanical analysis experiment. The frequency range is limited, but the DIRLD data indicate some similarities to the temperature-dependent data. The frequency-dependent infrared data do not show the direct correlation with the mechanical data that was evident in the temperature-dependent study. However, the frequency-dependent infrared data do provide some molecular insight, with a similarity to the temperature-dependent results in the 1800–1320cm−1 region, a quadrature signal increasing with increasing frequency in the 1320–1000cm−1 region, and complex changes in the low wavenumber region that are interpreted as polymer chain responses as a function of frequency.