Crystal and molecular structure of poly(aryl ether ether diketone)

The crystal and molecular structure of poly(aryl ether ether diketone) has been determined through wide-angle X-ray diffraction methods and conformational analysis. The unit cell, corresponding to a statistical structure, is orthorhombic, with cell dimensions a = 9.96 ± 0.10 A , b = 4.78 ± 0.05 A and c = 10.7 ± 0.10 A . The space group is Pbcn . The statistical subperiodicity along the chain axis c = 10.7 A is slightly larger than in the case of poly(aryl ether ketone) and poly(aryl ether ether ketone), which also have statistical structures. In addition, in the fibre spectra, weak haloes in layers are observed, which correspond to a periodicity three times larger, in agreement with the chemical constitution. While the phenylenic groups take approximately ordered positions in the crystals, this is not so for the constitutional units COCO and O of neighbouring chains.