THE CRYSTAL-STRUCTURES OF ARYL ETHER KETONE POLYMERS CONTAINING META-PHENYL LINKS

The X-ray diffraction patterns have been examined from the crystalline aromatic ketone polymer PEEKmK (aryl ether ether ketone ketone polymer containing meta-phenyl links) with the formula: [GRAPHICS] An orthorhombic crystal cell is proposed containing two chains with a = 7.71 angstrom, b = 6.05 angstrom and c = 39.9 angstrom. The lateral dimensions of the cell and the relative arrangement of chains is very close to that of the related all-para-phenyl polymer PEEK (poly(aryl ether ether ketone)). The para-linked phenyls are torsionally rotated out from the bc plane as in PEEK but the meta-phenyl ring remains parallel to the bc plane. The conformation of the meta-phenyl rings imposes an energy penalty, which contributes to the reduced melting point of the polymer.