Methods of description of orientation in polymers

The nonrandom orientational distribution of structural units, such as crystallites and chain segments, prevailing in an anisotropic bulk polymer sample can be represented fully by an orientation distribution function. Measurements of fluorescence polarization and wide‐line NMR are, in principle, capable of yielding information on the moments of the distribution function up to the fourth order. This work presents the method of analysis required to determine these moments. For this purpose, the distribution function is expanded in a series of generalized spherical harmonies. The method is an extension of a similar technique previously proposed for analysis of x‐ray diffraction data for determination of a complete crystallite orientation distribution function.