Complementary NMR studies on PPOn(LiTFSI) polymer electrolytes are reported. An improved sequence for measuring the diffusion constants of proton and lithium nuclei is presented, allowing the determination of the transport number of these systems. Our descriptive model, involving the coexistence of entangled and non-entangled parts of the high weight polymer chains, is supported by the various results concerning the relaxation times and the H-1 diffusion constants.