M C. Paira et al. Carbon 38(2000)1323-1337 1327 Fig. 1. SEM micrographs of the P120J fibres: (a)untreated;(b)75 W/3 min;(c)75 W/10 min;(d)100 w/3 min;(e)150 w/3 min; (f)150 W/10 min No change was observed for the PAN-based fibres after studied are presented in Table 3. Carbon and oxygen are plasma treatment, at the level of amplification used in the the most abundant elements at the fibres'surface. Other observations(Fig. 3) elements may be present, but only at atomic concentrations lower than 0. 1%, except for the PAN-based fibres, that 4.1.2.XPS contain a considerable amount of nitrogen. The global surface atomic compositions for all fibres Plasma treatment significantly increased the net surfaceM.C. Paiva et al. / Carbon 38 (2000) 1323 –1337 1327 Fig. 1. SEM micrographs of the P120J fibres: (a) untreated; (b) 75 W/3 min; (c) 75 W/10 min; (d) 100 W/3 min; (e) 150 W/3 min; (f) 150 W/10 min. No change was observed for the PAN-based fibres after studied are presented in Table 3. Carbon and oxygen are plasma treatment, at the level of amplification used in the the most abundant elements at the fibres’ surface. Other observations (Fig. 3). elements may be present, but only at atomic concentrations lower than 0.1%, except for the PAN-based fibres, that 4.1.2. XPS contain a considerable amount of nitrogen. The global surface atomic compositions for all fibres Plasma treatment significantly increased the net surface