Molecular mobility in ultrasonically devulcanized unfilled butadiene rubber
We have used 1H NMR relaxation and pulsed-gradient spin–echo diffusion, 13C NMR relaxation, and quantitative bulk measurements to characterize molecular mobility in unfilled butadiene rubber before and after an intense ultrasound treatment. In an effort to improve our understanding of the treatment process, we have performed the characterization at the molecular level. The 1H NMR T2 relaxation decay has been successfully described with a three-component model, which shows the evolution of the proportions and intermolecular mobilities of the changing spectrum of the motional species. The intramolecular mobility of the carbon backbone and structure has been examined with 13C NMR, which shows significant isomerization resulting from the ultrasound treatment. The diffusion rates of the ultrasonically treated samples reflect the measured changes in the molecular weights of the sol fractions. This investigation is the first to characterize the details of the delicate balance of the crosslinking, backbone modification, chain scission, and network degradation as an ultrasound treatment progresses.
Isayev, Avraam, "Molecular mobility in ultrasonically devulcanized unfilled butadiene rubber" (2004). Polymer Engineering Faculty Research. 74.