Nuclear magnetic relaxation and segmental motion of nitrocellulose in solution

Abstract

The transverse and longitudinal magnetic relaxation of solutions of cellulose nitrate (CN) with nitrogen contents of 13·5 and 11·9% have been studied in deuterated acetone in the temperature range from -100 to +70°C al two concentrations (34 and 50 wt. %). The two-component nature of the decay of the transverse magnetization points to the structural non-uniformity of CN in solution. The observed minima on the temperature dependence of the spin-lattice relaxation time in the laboratory system of coordinates, T1, and in a rotating system of coordinates are caused by segmental movement in open-packed regions of the solution. The contribution of slow movements to the spectrum of correlation times at the temperatures of the minimum T1 has been assessed. The values obtained for the activation energy for segmental motion in the unordered regions show that a vibrational-rotational mechanism predominates in the segmental motion of CN. © 1983