A study of the crystallographic equivalence of ether and ketone groups in poly(aryl ether ketone)s

Crystallographic equivalence of ether and ketone in all para-substituted PA EKs crystallized in form I was discussed in this paper. In a word, crystall ographic equivalence between ether and ketone groups is tenable when polyme r contains only phenyl rings in the repeat unit. If a polymer contains a di phenyl group in the repeat unit, two cases should be distinguished. In the case of PEDEKK and PEEKDK, crystallographic equivalence between ether and k etone linkages is untenable, However, in the case of PEDK and PEDEKDK, crys tallographic equivalence between ether and ketone linkages is still tenable .