A study of blends of poly(ether ether ketone ketone) and poly(ether sulphone) : Effect of the addition of poly(ether ether ketone) oligomer
The thermal and viscoelastic behaviour and mechanical properties of blends of poly(ether ether ketone ketone) (PEEKK) with poly(ether sulphone) (PES) have been investigated. Additionally, poly(ether ether ketone) (PEEK) oligomer was added as the third component to the above blend in order to improve its compatibility and mechanical properties. From the results of viscoelastic measurements and differential scanning calorimetry (DSC) for the blends of PEEKK with PES, it was revealed that the blends are partially compatible systems, especially at low levels of PES, and their storage modulus at around 200°C rises as the PES content increases. When PEEK oligomer was added to the PEEKK/PES blend as a third component, its compatibility and flexural strenght were considerably improved. This was consistent with SEM micrographs of the blends. Concerning the crystallisation behaviour, although the melting point (Tm) and crystallisation temperature (Tc) were almost constant values regardless of the PES content of the blends of PEEK/PES, Tm and Tc were lowered as the PEEK oligomer content increased for the blends of PEEKK/PES/PEEK oligomer.