Fiber zero surface coverage

IGC has been used at zero surface coverage to characterize the surfaces of cellulose (5), cellophane (6), and poly(ethylene terephthalate) film (7 ). Surface properties of Intact textile fibers were also studied by IGC (8). Domlngo-Garcla et al. (9 ) have recently characterized graphite and graphltlzed carbon black surfaces with this method, and some zero coverage results on carbon fibers have appeared (10). 

The variation In lsosterlc heat of adsorption for n-nonane on T-300T fibers with surface coverage Is presented In Figure 3. Also Included are the values for qgt at T 0, obtained by adding RT to the differential heat of adsorption, q, at zero coverage, the monolayer capacity for n-nonane at 50°C and the enthalpy of liquefaction for n-nonane at 50°C, -AH. ... 

Since IGC is able to generate adsorption isotherms and to evaluate acid/base interactions for specified adsorbate-adsorbent pairs, it follows that the technique is able to develop a detailed picture of surface properties for non-volatile stationary phases. This is illustrated, again for carbon fibers, by Vukov and Gray (48). They combine IGC information at essentially zero coverage of the injected probes with finite concentration data to obtain heat of adsorption values ranging from zero to multi-layer coverage. Their meticulous study shows the effects of thermal pretreatment on fiber surface characteristics, and underscores the convenience and power of IGC to generate information otherwise far more difficult to obtain. 

Zero coverage. In order to eliminate physically adsorbed species, fibers were cleaned by heating at 160°C In a N2 (Linde, ultra high purity, with C02 content less than 1 ppm) atmosphere until constant retention volumes were obtained (100 to 120 h). Using finite concentration IGC and n-alkanes as sorbates, the surface area of these fibers was determined to be 0.40 m g"1 and 0.59 m g 1 for T-300 and P-55, respectively. The n-alkanes octane to trldecane (analytical grade) were obtained from Polyscience Corporation (Quantklt). Retention data were measured with a Hewlett-... 

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