M C. Paira et al. Carbon 38(2000)1323-1337 Fi.2. icrographs of the ribbon fibres:(a) untreated; (b)75 W/3 min;(c)75 W/10 min oxygen concentration. The fibres are extensively oxidised 4.1.3. Wettability fter 3 min, even at the lower plasma power The results obtained for the dispersive and non-disper Detailed analysis of the P120J and ribbon fibres, before sive components of the surface energy are presented and after plasma treatment at 75 w for 3 min, revealed the Table 5 type of functionalities present on the fibres surface. The The dispersive component remains considerably con- bands obtained by spectral deconvolution of the Cls peak stant for all the fibres studied, showing no appreciable re shown in Fig. 4, and the functionalities attributed to variation after plasma treatment. In the limit, it could be each are presented in Table 4. The same functionalities considered that a slight tendency to an increase in ys is were detected for both types of fibres, namely hydroxyl observed from the untreated to the plasma treated fibres ether groups, quinone type groups and carboxylic acid, in The magnitude of the results is comparable to that order of decreasing concentration. The relative composi- in the literature for other types of fibres [15]. The non- tion, expressed as the ratio of each peak area to the total dispersive contribution to the surface energy is very small )) is represented in Fig. 5 A crease is. however observed from untreated The hydroxyl or ether groups are present in a higher to treated fibres. The ribbon fibres also show the same concentration in the untreated fibres. Plasma treatment behaviour. Higher values were obtained for the P75s, but introduces more quinone and carboxylic acid groups, this probably reflects interactions with the fibre sizing. The relative to the hydroxyl groups, but the concentration of results found in the literature for other pitch-based fibres. the latter is still dominant. The oxygen uptake is, in although few and obtained with different wetting tech- general, higher for the ribbon fibres for all contributing niques are comparable with those determined in this work. functionalitie No data were obtained for the pan-based fibres due to1328 M.C. Paiva et al. / Carbon 38 (2000) 1323 –1337 Fig. 2. SEM micrographs of the ribbon fibres: (a) untreated; (b) 75 W/3 min; (c) 75 W/10 min. oxygen concentration. The fibres are extensively oxidised 4.1.3. Wettability after 3 min, even at the lower plasma power. The results obtained for the dispersive and non-disper￾Detailed analysis of the P120J and ribbon fibres, before sive components of the surface energy are presented in and after plasma treatment at 75 W for 3 min, revealed the Table 5. type of functionalities present on the fibres’ surface. The The dispersive component remains considerably con￾bands obtained by spectral deconvolution of the C1s peak stant for all the fibres studied, showing no appreciable are shown in Fig. 4, and the functionalities attributed to variation after plasma treatment. In the limit, it could be d each are presented in Table 4. The same functionalities considered that a slight tendency to an increase in g is S were detected for both types of fibres, namely hydroxyl or observed from the untreated to the plasma treated fibres. ether groups, quinone type groups and carboxylic acid, in The magnitude of the results is comparable to that reported order of decreasing concentration. The relative composi- in the literature for other types of fibres [15]. The non￾tion, expressed as the ratio of each peak area to the total dispersive contribution to the surface energy is very small. peak area (A /A ), is represented in Fig. 5. A significant increase is, however, observed from untreated C1s(i) C1s(total) The hydroxyl or ether groups are present in a higher to treated fibres. The ribbon fibres also show the same concentration in the untreated fibres. Plasma treatment behaviour. Higher values were obtained for the P75S, but introduces more quinone and carboxylic acid groups, this probably reflects interactions with the fibre sizing. The relative to the hydroxyl groups, but the concentration of results found in the literature for other pitch-based fibres, the latter is still dominant. The oxygen uptake is, in although few and obtained with different wetting tech￾general, higher for the ribbon fibres for all contributing niques are comparable with those determined in this work. functionalities. No data were obtained for the PAN-based fibres, due to