Molecular orientation and microstructure of roller-drawn sheets of poly(ether ether ketone)

The rolling and roller-drawing of poly(ether ether ketone) (PEEK) sheets were carried out in the roller temperature range of 165-262°C. The crystal orientation functions of the PEEK sheets were determined from the azimuthal intensity distribution of wide-angle x-ray diffraction, and the orientation behavior in the amorphous region was characterized by the measurements of sonic modulus and polarized fluorescence. The orientation functions increase monotonically with increasing draw ratio. The orientation function in the amorphous region is close to that of crystal orientation function of the same sample. The long period evaluated by small-angle x-ray scattering is almost constant over the draw ratio range studied, whereas the crystallite size along the 001 plane, D₀₀₁ tends to increase with increasing draw ratio. The value of the crystallite size exceeds the product of the crystallinity and the long period. The result suggests the formation of the crystalline linkages that penetrate the periodic layers. © 1994 John Wiley & Sons, Inc.