Proton Magnetic Resonance in Polyisobutylene at Various Temperatures, Pressures, and Frequencies

Abstract

New experimental data are reported for the effects of pressures up to 1060 kg/cm² on the hydrogen nuclear magnetic resonance line width for polyisobutylene, at various temperatures from — 100°C to 32°C. The spin‐lattice relaxation time is measured at room temperature for frequencies from 1.9 to 39 mc, in which range it varies approximately as the first power of the frequency, and is also investigated as a function of pressure at fixed frequency. Pressure effects on the line width are discussed in terms of an activation energy dependent on the volume. The frequency dependence of the relaxation time indicates, but does not completely determine, a distribution of thermal motion correlation times. The effects of three hypothetical distributions are computed.