Peek Oligomers - a Model for the Polymer Physical Behavior .2. Structure and Thermal-behavior of Linear Monodisperse Oligomers

Jonas, Alain M. [UCL] Legras, Roger [UCL] Scherrenberg, R. Reynaers, H.

The thermal and structural properties of monodisperse linear poly(oxy-1,4-phenyloxy-1,4-phenylenecarbonyl-1,4-phenylene) (PEEK) oligomers have been investigated by differential calorimetry, optical microscopy, and wide-angle and small-angle X-ray wattering. The complex melting, observed for the longest oligomers, is related to variations in the relative placement of the ether and ketone bridges of the chains in the lamellae (eclipsed and staggered lamellae). Chain packing is discussed in terms of chain staggering, and appropriate conclusions are drawn concerning the variations of the polymer unit cell dimensions with crystallization temperature. Two different types of spherulites have been detected for the longest oligomer; these are shown to result from differences in the preferred main orientation of the (100) planes of the lamellae.