Relaxation Spectrum of Polymer Networks Formed from Butyl Acrylate and Methyl Methacrylate Monomeric Units

Abstract

The aim of this work is to study the merging of the main α and the secondary β relaxations in poly(butyl acrylate)-i-poly(methyl methacrylate) sequential interpenetrating networks in comparison to net-poly(butyl acrylate)-co-poly(methyl methacrylate) random copolymer networks. In both cases 10% of ethylene glycol dimethacrylate was used as cross-linking agent. The cross-linking density of these networks is high enough to force a certain degree of compatibility of the IPNs, as shown by dynamic-mechanical analysis and thermally stimulated depolarization currents, TSDC. Dielectric relaxation spectroscopy was used to characterize the relaxation behavior in the frequency domain. The strength of the α dielectric relaxation in poly(methyl methacrylate) network is small and the merging with the β relaxation is not apparent in the experimental frequency range. On the contrary, in poly(butyl acrylate) networks it is the strength of the secondary relaxation which is small compared to that of the α relaxation and the...