Rotating-frame spin-lattice relaxation time imaging by radio-frequency field gradients: visualization of strained crosslinked natural rubbers

NMR imaging by radio-frequency field gradients (B1 gradients) is especially convenient for heterogeneous samples and/or in the case of relatively short transverse relaxation times. The method has been combined with the application of two spin-lock periods of different duration so as to produce rotating-frame spin-lattice relaxation time (T1rho) images. In the case of natural rubber samples with different crosslink densities, such images are not only characteristic of the crosslink density but also reveal the way in which the material has been stressed. The strained parts can be visualized either directly or through histograms showing the T1rho distribution over the whole sample.