P.E. Vickers et al. Carbon 38(2000)675-689 一CH2NH2 日一C2H4N o00 0 Percentage treatment Fig. 3. Variation of even mass positive ions with surface treatment. offer an adequate explanation for the improvement in required to sweep out an adsorbed species is the net mechanical properties observed in CFRP materials, which retention vol may result from changes in the thermodynamic properties of the surface. An investigation into these aspects of the N=JFCIN fibre surface by IGC and dCaa was therefore undertaker Where is the compression factor, Fc the corrected flow 3. 2. Surface thermodynamics properties by means of rate, and IN the net retention time. The value of IN will therefore be large for a strongly adsorbed species. The free energy of adsorption for a given probe on the surface is related to N by Inverse gas chromatography has long been used to △G=Rrhn(N)+C determine both ys, the dispersive contribution to the surface free energy, and acidity and basicity constants for where R is the gas constant and T the working tempera- polymers [21-23], fillers [24, 25] and fibres [21]. In IGC ture. the term inverse means that the stationary phase of the The constant C is a term that takes the weight and chromatographic column is of interest in contrast to specific surface area of the stationary phase, and the onventional GC. Molecular probes of known physico- standard state of the probes in the gaseous and adsorbed hemical properties are passed through a column packed state into account [26 with the material of interest in an inert carrier gas such as The determination of AG. or RT In( V) values for all N2, at such a low concentration that they behave in- material-probe pairs will permit an estimation of y s and dependently of each other. This is known as IGC at infinite acid-base constants of the materials under test. y. and dilution or zero coverage. This approach permits the acid-base constants will be assessed using n-alkanes and characterisation of the surface or bulk properties of the specific probes, respectively. For all the probes used packing material under test. The volume of carrier gas RT In(N) values are reported in Table 5 Table 4 lon assignments for even mass ions detected on the fibre surface by ToF-SIMS C,HN. C, H, O C,H CrH, NO, C3HN, C3 H,O, C,H&, C,H,N2 CH C,HNO CHN CsH.O C, H.O. CH. C,h,N,o C,HANO, C3H,NO,, CsHIN, C H,O2, CsH1oO, C4H1oN2, CHSN,OP.E. Vickers et al. / Carbon 38 (2000) 675 –689 681 Fig. 3. Variation of even mass positive ions with surface treatment. offer an adequate explanation for the improvement in required to sweep out an adsorbed species is the net mechanical properties observed in CFRP materials, which retention volume, V . N may result from changes in the thermodynamic properties of the surface. An investigation into these aspects of the V 5 jF t (1) N CN fibre surface by IGC and DCAA was therefore undertaken. Where j is the compression factor, F the corrected flow- C rate, and t the net retention time. The value of V will N N 3.2. Surface thermodynamics properties by means of therefore be large for a strongly adsorbed species. The free IGC energy of adsorption for a given probe on the surface is related to V by: N 3.2.1. Behaviour of the probes Inverse gas chromatography has long been used to 2 DG 5 RT ln(V ) 1 C (2) a N d determine both g , the dispersive contribution to the s surface free energy, and acidity and basicity constants for where R is the gas constant and T the working tempera￾polymers [21–23], fillers [24,25] and fibres [21]. In IGC ture. the term ‘inverse’ means that the stationary phase of the The constant C is a term that takes the weight and chromatographic column is of interest in contrast to specific surface area of the stationary phase, and the conventional GC. Molecular probes of known physico- standard state of the probes in the gaseous and adsorbed chemical properties are passed through a column packed state into account [26]. with the material of interest in an inert carrier gas such as The determination of DG or RT ln(V ) values for all a N d N , at such a low concentration that they behave in- material-probe pairs will permit an estimation of g s and 2 d dependently of each other. This is known as IGC at infinite acid–base constants of the materials under test. g s and dilution or zero coverage. This approach permits the acid–base constants will be assessed using n-alkanes and characterisation of the surface or bulk properties of the specific probes, respectively. For all the probes used, packing material under test. The volume of carrier gas RT ln(V ) values are reported in Table 5. N Table 4 Ion assignments for even mass ions detected on the fibre surface by ToF-SIMS m/z Possible composition 42 CHN 2 4 , C H O, C H 22 36 56 C H NO, C H N 22 36 , C H O, C H , C H N 34 48 242 70 C H NO, C H N 34 48 , C H O, C H 4 6 5 10 84 C H NO, C H N 4 6 5 10 , C H O, C H O , C H , C H N O 5 8 4 4 2 6 12 3 4 2 86 C H NO, C H NO , C H N 4 8 3 4 2 5 12 , C H O , C H O, C H N , C H N O 4 6 2 5 10 4 10 2 3 6 2