MAGNETIC-FIELD AND TEMPERATURE EFFECTS ON THE SOLID-STATE PROTON SPIN-LATTICE RELAXATION-TIME MEASUREMENTS OF WOOD AND PULPS

The proton spin-lattice relaxation times (T-1) for a series of progres sively sulphonated black spruce pulps were measured at two static magn etic fields and al a variety of temperatures. These determinations sho wed that the frequency of the anisotropic molecular motions of carbohy drates and lignin, responsible for spin relaxation on wood and pulps, is of the order of 10(-9)s. For cross-polarization measurements with a 300 MHz solid state NMR spectrometer, room temperature seems to be cl ose to the T-1 versus correlation time minimum.