The influence of catalyst remnants on thermal degradation during melt processing of high melting ethylene-carbon monoxide copolymers

The thermal stability of alternating ethylene-carbon monoxide copolymers (P OK-C-2), synthesised using a palladium-bidentate catalyst, is predominantly determined by the amount of 'active' catalyst species present in as-synthe sised polymer for a palladium content >6 ppm. For a lower active palladium content the intrinsic limitations to the thermal stability of the chemical structure become noticeable. It is demonstrated that the thermal stability of polymers prepared under optimised conditions, (e.g. low catalyst content ) is sufficient to allow melt processing for at least a few minutes of resi dence time above the melting temperature. Homogeneous transparent melt crys tallised films are obtained and small strands were drawn at 225 degreesC to a ratio of 8. The mechanical properties of these oriented samples are comp arable with commercially available PET and PA-6,6 melt spun fibres. The cry stalline fraction in these samples is mainly present in the very dense POK- alpha form, indicating that the formation of a significant amount of bulky chain defects during thermal exposure, like Paal-Knorr and aldol type conde nsation products, is prevented. (C) 2001 Elsevier Science Ltd, All rights r eserved.