C-13-Detected H-1 spin diffusion and H-1 relaxation study of multicomponent polymer blends

The miscibility of two macroscopic phase separated polymers, a propylene-et hylene-diene terpolymer and an atactic polypropylene, has been investigated by a combination of several solid-state NMR techniques. Carbon-detected pr oton T-1 rho and carbon-detected proton T-1 in systems conditioned by two-d imensional heteronuclear wide-line separation (WISE) were used. Both techni ques are sensitive to spin diffusion between phases, with WISE being suited to making it stand apart from the basic relaxation process. These two tech niques yield similar but different assessments of the presence and amount o f phase separation present. This is not surprising considering that they in volve different relaxation time scales, from milliseconds to seconds. An ad ditional comparison is made with differential scanning calorimetry and xeno n NMR results, which also address this problem. In addition, the WISE data permit an estimate of the aPP domain size.