Study of Molecular Motions in Crystalline Polymers by NMR Absorption Line-width Measurement

Abstract

A brief review is given of principal results obtained in the author's laboratory during last several years concerning applications of NMR absorption line measurement to the study of molecular motions in crystalline polymers. The anisotropy of NMR is measured on a highly oriented and completely crystalline polyoxymethylene obtained from tetraoxane single crystal by solid-state polymerization and is compared with the calculated. By dividing the absorption signal from polyterafluoroethylene into three parts, the third phase is found to be intermediate between the amorphous and crystalline phases. The well-known three relaxation phenomena (α, β, and γ) of polyethylene are discussed in terms of line-width narrowing and mobile fraction increase with elevating temperature. Trans-1, 4-polybutadiene gives rise to an anisotropic large scale motional narrowing at the solid phase transition temperature.