【Abstract】 PEKEKK(T) and PEKEKK(T/I) have two different crystal structures: a conventional Form Ⅰ structure, the same as that observed in PEEK, which is usually developed from melt crystallization, and a new Form Ⅱ structure which can be developed from cold crystallization or solvent induced crystallization(by exposing the glassy state sample to methylene chloride). PEKEKK(I) does not show polymorphism.更多还原