Broadband dielectric spectroscopic characterization of the hydrolytic degradation of carboxylic acid-terminated poly(d,l-lactide) materials

Permittivity data for degraded and undegraded materials were fitted to the Havriliak-Negami equation with subtraction of the d.c. conductivity contribution to uncover pure relaxation peaks. Parameters extracted from these fits were used to construct Vogel-Fulcher-Tammann-Hesse (VFTH) curves and distribution of relaxation time, G(τ), curves for all samples. It was seen that the relaxation times for the α-transition in both degraded and undegraded samples showed VFTH temperature behavior. G(τ) curves showed a general broadening and shift to lower τ with degradation, which can be explained in terms of a broadening of molecular weight within degraded samples and faster chain motions.