chain-orientational disorder

in polymer crystals
https://doi.org/10.1351/goldbook.C00957
@S06060@ resulting from the statistical coexistence within the crystals of identical chains with opposite orientations. A typical example is provided by the up-down statistical coexistence of anticlined chains in the same crystal structure.
Source:
Purple Book, 1st ed., p. 80 [Terms] [Book]