A proof of principle experiment: Structural transitions in self-healing poly (ethylene co-methacrylic acid) ionomers using acoustic and ultrasonic time dependent resonant spectroscopy

Abstract

We demonstrate a method for assessing structural transitions in self-healing poly (ethylene co-methacrylic acid) ionomers as a function of time, by observing the evolution of their acoustic and ultrasonic resonant spectra and associated quality factors during the post-damage healing phase. Two samples composed of EMAA-0.6Na and EMAA-0.3Na were scanned from 1 kHz to 2 MHz before and after a damage event. After damage, time varying resonances were discovered using time dependent resonant spectroscopy (TDRS), and several of these resonances continued to evolve after visible changes in the samples ceased. These time dependent resonances enable characterization of energy dissipation, relaxation and structural ordering in self-healing ionomers. In addition, TDRS may provide a method for isolating material properties that affect the healing process, such as ion content and their associated structures as well as the effect of sample aging, which may lead to improved structural models.