Temperature dependence among the grant and Paul parameters as derived from 13C NMR polymer spectra

Abstract

Improvements in the ¹³C NMR Grant and Paul parameters as applied to polymers have been obtained by noting that the “corrective terms” can be temperature‐sensitive. A corresponding temperature sensitivity was not observed for the primary parameters, α through ϵ. Results are given for a hydrogenated polybutadiene and six different ethylene–1‐olefin copolymers where the standard deviation between calculated and observed chemical shifts has been improved from 1.04 to 0.30 ppm. Since the “corrective terms” in the Grant and Paul empirical analyses of chemical shifts reflect the conformational character of polymers, it is shown that values for these terms can best be obtained directly from the system under study.