Method of measurement of nonzero average dipolar spin coupling in molten polymers

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Abstract
The present paper concerns a problem more general than that related to NMR studies of molten polymer systems. It aims at defining a method of measurement of the nonzero average dipolar spin coupling in the case where (i) spin–spin relaxation rates due to nucleus motion, (ii) field inhomogeneities, and (iii) chemical shifts are of the same order of magnitude as the nonzero average dipolar coupling, in frequency units. It is shown that by using pulse sequences giving rise to appropriate response functions of the transverse magnetization, contributions (i), (ii), and (iii) can be eliminated. As an example, the experimental determination of the nonzero average dipolar coupling is considered, using a cis‐1,4‐polybutadiene sample.