Model Calculation for Viscoelastic and Dielectric Relaxation Functions of Non-Entangled Star Chains with Arm Length Distribution

Abstract

Based on Rouse-Ham dynamics, we examined viscoelastic and dielectric relaxation functions of unentangled model star chains of f arms with and without arm-length distribution. We assumed that each arm possesses the dipole moment aligned in the same direction along the chain contour from the center to the arm end, and thus exhibits the dielectric normal mode process related to center-to-end vector fluctuation of arms. The model calculation suggested that the arm-length distribution influences the mode distribution of the dielectric normal mode relaxation more strongly as compared to that of the viscoelastic relaxation that reflects the orientational anisotropy of the whole segments of the star molecules. This difference is due to the difference in the contribution of the Rouse-Ham eigenfunctions to these two relaxation functions.