Comparison of Dielectric and Mechanical Relaxation Spectra in Terminal Region: Undiluted cis-Polyisoprene

Abstract

Dielectric relaxation spectrum g(τ) for the normal mode process in undiluted cis-polyisoprene(cis-PI) was calculated from the dielectric data reported previously. The shape and the broadness of the spectra were in accord with the prediction by the 3 mode model. The following relationship between complex dielectric constant ε*(ωw) for the normal mode process and dynamic shear modulus G*(ω) in the terminal region was derived based on the tube theory by Doi:
1-ε*(ω)/Δε=G*(ω)/G_N⁰
where ω is the angular frequency; Δε the dielectric relaxation strength; G_N⁰ the plateau modulus in the rubbery region. To check this relationship, the relaxation spectrum H(τ) converted from the retardation spectrum reported by Nemoto et al. was compared with g(τ). The loss modulus G″(ω) reported by Carella et al. was also compared with the dielectric loss factor ε″(ω).