CHEMICAL MODIFICATION OF POLY(ETHER ETHER KETONE) FOR SIZE-EXCLUSION CHROMATOGRAPHY AT ROOM-TEMPERATURE .2. ON THE RELIABILITY OF THE DERIVATIZATION PROCEDURE FOR PEEK MOLECULAR-MASS DETERMINATION-APPLICATION TO PEEK-CARBON FIBER-COMPOSITE

Some poly(ether ether ketone) (PEEK) samples were analysed by light sc attering (l.s.) before and after complete sulfonation. Afterwards, the average molecular masses and molecular-mass distribution of the same PEEK samples are determined by high-temperature size (steric) exclusio n chromatography (s.e.c.) for unmodified PEEK and by room-temperature s.e.c. (r.t.s.e.c.) for totally sulfonated PEEK. From this work, it ap pears that l.s. and s.e.c. measurements using sulfonated or unsulfonat ed PEEK sample give identical results within the limit of the s.e.c. a nd l.s. accuracy. This verification assesses the reliability of the de rivatization method used to perform r.t.s.e.c. It is also shown that n umber-average molecular masses ((M) over bar(n)) of fully fluoroarylke tone-terminated PEEK determined by F-19 nuclear magnetic resonance exp eriments agree very well with (M) over bar(n) values from s.e.c. These results support the validity of both s.e.c. methods used in this work . Finally, a PEEK-carbon fibre composite is characterized. The fibre c ontent is evaluated. The derivatization process is applied to the matr ix and the molecular parameters are obtained by r.t.s.e.c.