Strongly hydrogen-bonded polymer crystals offer a unique opportunity to examine the modes of motion available to polymer segments which are inhibited by periodic constraints. Solid state deuterium NMR spectroscopy coupled with lineshape simulations has been previously used to examine the segmental dynamics of nylon 66 and PPTA [poly(p-phenyleneterephthalamide)]. Thin information was coupled with that available from X-ray scattering to develop a description of the dymolecules in the crystalline domains to mechanical deformation and reveals approaches that could facilitate chain through the polymeric crystal.