Viscoelastic properties of high molecular weight polymers in the molten state

Abstract

This paper presents an analytical calculation of the relaxation and retardation spectra for narrow distribution polymers, binary blends and whole polymers. The retardation spectrum exhibits two peaks, one independent of molecular weight (transition region), and one shifting toward long times as the molecular weight increases (terminal region). The relaxation spectrum derived from this analytical retardation spectrum is shown to have a sharp cut-off at large times, this cutoff being smoothened when using conventional approximation methods to deriveH(τ) from the experimental data. — The analytical retardation spectra of integrated relaxation spectra (from the retardation spectra) should be useful in the tests of constitutive equations.