Co-crystallization in PEEK Copolymers

Thermal and wide-angle x-ray scattering (wAxs) studies of a new set of copolymers of polyether ether ketone (PEEK) with ether diphenyl ether ketone (EDEK) have been undertaken. The copolymerization modifies the properties of PEEK. At low levels of comonomer content the incorporation of the comonomer unit lowers the melting temperature and reduces the degree of crystallinity. At higher levels the melting point increases towards that of the PEDEK homopolymer. The x-ray structure is very similar to that of PEEK, consistent with rejection of the comonomer at low levels of comonomer content. At high levels the structure is very similar to that of PEDEK while at intermediate levels the structure is found to 'swtich' from that of PEEK to that of PEDEK, consistent with co-crystallization of the two monomer units.