All features of the X-ray diffraction pattern of polyoxymethylene produced by radiation-induced, solid-state polymerization of trioxane have been examined. The heavy radial streaking observed on both our own and on previous workers' patterns has been explained and the hexagonal unit cell dimensions have been calculated.
We have computed sets of parameters for chain configurations which could exist within the accuracy of the measurement, and have shown that each configuration arises as a result of various indexing of the diffraction pattern. In conclusion we argue that such helical structures are better described in terms of their average chain parameters rather than by attempting to define an exact unit cell height or identity period. Finally, we have calculated a set of values for the parameters which exactly describe the polyoxymethylene chain.