FT Raman Spectroscopy was used to study the interphasial structure in carbon fiber/polyetheretherketone (CF/PEEK) composites. Spectra of APC 2 laminates with different thermo mechnical histories show a broad band around 1300 cm-1 distinctive either to theA1g scattering of carbon fiber or to PEEK overtones

suggesting different PEEK structure in composites compared to neat resin. To simulate formation of the interphasial structure in the composites

AS4 fiber was coated with PEEK through its chlorophenon solution.The FT-Raman study of the coated fibers reveals that the 1300cm-1 band originates from overlapping of the dispersive branches of graphite A1g and PEEK ring C-O scattering. Comparison of the spectra of coated fibers with those of the melted ones reveals profound effects of melting on interphasial structure.Raman spectra of the unmelted coatings were dominated by E2g and non-dispersive A branches of graphite and localized modes of PEEK.When melted

the spectra became highly dependent on coaling thichness.When thickness of PEEK layer is about a dozen of nanmeter

the broad band around 1600cm-1 can be found stronger compared to that of unmelted coatings.The band center shifted to lower wavenumber when coating thickness decreased.When the PEEK coating approached the order of nanometer

spectra typical to amorphous and mesophase carbon were found.The result suggest that the structure of the polymer near carbon fiber must be different from that in the bulk if PEEK is allowed to melt.The structure different is discernible at least on two scales

one identical to the dimension of chain coil and amother to thickness of the segments.While structure on the latter scale needs further work to be understood more explictily

the limited results hinted matching of graphite crystallites with the polymer segments.Within a dozen of nanometers to the fiber surface orientation of the ether-ether-ketone segments are no doubt stronger than those in neat PEEK. It was thus deducted that interphase forms in composite during processing through interaction of the EEK segments with graphite in short range neighbor to carbon fiber surface and chain orientation within a larger range of tens of nanometers.