Polyethylene spin-linear relaxation time

Information on the local structure of polymers is not limited to proton-proton spin diffusion experiments. Spin diffusion among the carbons can also be used [97], However, because of the low gyromagnetic ratio and natural abundance of the carbon-13 nuclei, it is less efficient than proton-proton spin diffusion. At natural abundance, the rate of spin diffusion is usually too low to compete with the rate of spin-lattice relaxation in most polymers. However, an interesting exception is that of semi-crystalline polymers such as linear polyethylene and cellulose which have very long longitudinal relaxation times and for which natural-abundance spin... 

---