P. C. M. M. Magusin, R. A. Orza, V. M. Litvinov, M. van Duin, K.SaalwäĘchter.
Chain Mobility in Crosslinked EPDM Rubbers. Comparison of 1H NMR T2 Relaxometry and Double-Quantum 1H NMR
In: Spectroscopy of Polymers: Innovative Strategies for Complex Macromolecules (ACS Symp. Ser. Vol. 1077), ch. 13, pp. 207-220. Editors: H. N. Cheng, T. Asakura, A. D. English. American Chemical Society, Washington 2011
1H NMR transverse relaxation and double-quantum (DQ) build up have been compared for a series of EPDM grades crosslinked with different amounts of sulfur or peroxide. The modulus at 100% elongation of the same EPDM samples correlates linearly to the effective transverse-relaxation and DQ build-up rate, suggesting that both rates are proportional to the total network density caused by chain entanglements and crosslinks. For none of the rates, however, the linear trends of sulfur- and peroxide-crosslinked EPDM coincide. This suggests that sulfur- and peroxide-crosslinked EPDM networks are qualitatively different, which is confirmed by different distributions of residual dipolar coupling constants.