Crystallization and Morphology of Poly (Aryl Ether Ether Ketone)

The morphology of polyaryl ether ether ketone PEEK has been studied using optical microscopy at room temperature and at elevated temperatures, small angle light scattering Hv and Vv, transmission electron microscopy bright field, dark field, and selected area electron diffraction, and wide and small angle x-ray scattering. As expected, density of nucleation and hence spherulite size depends on melt temperature. Higher melt temperatures gives rise to low nucleation density and hence large spherulites. The spherulite growth rate is independent of melt temperature and depends on crystallization temperature. The sign of the spherulite birefringence was determined between room temperature and 320 C by polarizing microscopy and at room temperature by Vv light scattering. In this temperature range the spherulites were negatively birefringent. From selected area electron diffraction, the crystal unit cell b- axis is found to align along the radius of the spherulite. The crystallographic 110 plane, which makes and angle of 52.7 degrees with the radial b-axis, appears to be the preferred growth plane. Chain polarizability was also calculated using refined atomic coordinates and the bond polarizabilities. PEEK crystals were more stable in the electron beam, by about an order of magnitude, than polyethylene. Keywords PEEK Polyaryl ether ether ketone Spherulite Birefringence Ketones.