Dispersion component of surface energy

FIGURE 33.3 Dispersive component of surface energy and dispersion quality in ESBR as a function of heat treatment of N234. 

Dispersive component of surface energy. According to Fowkes (14). when only dispersion interactions are being exchanged, for example with n-alkanes probes, the energy of adhesion is given by... 

Inverse gas chromatography at infinite dilution appears to be a powerful tool for studying the surface properties of carbon fibres and polymer matrices. The use of alkane probes and acid/base probes allows the characterization of the surfaces in terms of their London dispersive component of surface energy and their acid/base or acceptor/donor characteristics. A strong correlation was obtained between fibre-matrix adhesion, measured by a destructive fragmentation technique, and the level of acid base interactions calculated from the chromatographic analysis. 

When the behavior of carbon black and silica is compared in compounded rubber, it is evident that silica adsorbs less rubber than carbon black. In addition to the differences in the chemical compositions of the surfaces this difference is caused by the differences in the dispersive components of surface energies of each filler. Car-... 

Once the dispersion component of surface energy of a liquid is known, the polar component can be obtained from the surface tension using Eqn. 10. The approach based on Eqns. 9 and 10 can then be used to estimate surface energies of solids, particularly polymers, very much in the same way as Ys values are obtained from Eqn. 8. Here, yi2 is eliminated between Eqn. 10 and the Young equation, giving... 

All other polar probes exhibit higher net retention volumes, En. and the difference between their net retention volume and that of the n-alkanes for the same value of the dispersive component of surface energy leads to the value of the free energy of desorption, AGjp, corresponding to the specific acid-base interaction, expressed as ... 

Properly applied fatty acids provide the filler with a hydrocarbon-like surface, which is much less polar than the filler itself For example, the treatment of a precipitated calcium carbonate with a fatty acid coating was found to reduce the dispersive component of surface energy from 54 to 23 mj/m 3]. As a result, the filler is made more compatible with many polymer types, resulting in benefits such as faster incorporation and mixing, better dispersion, less energy consumption, lower viscosity, and easier extrusion. The filler generally also has lower adsorbed water content. 

Two test liquids, such as deionized water and formamide of known polar and dispersion components of surface tension were used to evaluate the polar and dispersion components of surface energies of FBI through measurement of their contact angle by the sessile drop method. 

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