CHARACTERIZATION OF PAN-BASED CARBON-FIBERS WITH LASER RAMAN-SPECTROSCOPY .1. EFFECT OF PROCESSING VARIABLES ON RAMAN BAND PROFILES

Laser Raman spectroscopy (LRS) has been employed to characterize the s tructure and morphology of a series of carbon fibres, to assess the co mbined effects of ultimate firing temperature (UFT) and pre-graphitiza tion drawing during manufacture and, finally, to investigate the influ ence of oxidative treatment upon the integrity of the fibre surface. T en types of PAN-based carbon fibres of varying modulus, diameter and m anufacturing method, were examined. All their spectral features were r ecorded and analysed in terms of position, bandwidth and band intensit y. Low-modulus fibres, produced at low graphitization temperatures, ex hibit weak and broad Raman bands in the 1200-1700 cm(-1) frequency reg ion. With the increase of the firing temperature, the spectral feature s sharpen and new lines appear at higher frequencies. The observed cha nges in the Raman spectra are discussed in detail and related to alter ations in the conditions of manufacture.