Dispersion component of surface

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

The three EME coupling agents in Table 1 were analyzed using contact angle measurements to determine their polar and dispersion components of surface tension. From the surface tension data, wettability envelopes were constructed and compared with the surface tension properties of the epoxy coating [4], These data predicted that EME 47 would be wet by the epoxy, but not EME 23. This is believed to be the reason for the very low peel strength when EME 23 was employed [4],... 

Method based on the quantity, a(yl)1/2 of the London dispersive component, > of surface free energy multiplied by cross sectional area, a, of nonpolar probes, such as n-alkanes [87,125]. 

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. 

The work of adhesion increases as the dispersive component of surface free energy increases. Table 5.11 gives the values of the dispersive component available in the literature for different fillers. 

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-... 

Densification of carbon black by compression increases the dispersive component of surface free energy. This process is initially not proportional to density, but after some threshold value at around 0.7 g/cm the dispersive component has a linear... 

The dispersive component of surface free energy 7 may be calculated from Eq.(ll) with the use of experimentally determined AGcHj [23-47]. 

Surface characteristics of the series of commercially available aluminas with the use of IGC were reported by Papirer et al. [34]. Values of the dispersive component of surface free energy 7 varied from 65 to 100 mJ/m. Authors determined also Kd and Ka values. The variation of the electron donor parameter Kd was almost negligible (2.1-2.7), while Ka parameter increased from 5.6 to 9.9 units. The significant changes for acidity were related to the Si02 content. Acidity parameter, Ka, reached a constant value for a Si02 content of about 1000 ppm. However, AN and DN were taken from Gutmann s proposal... 

Table 7 Dispersive Components of Surface Free Energy of Adsorption and Related Thermodynamic Properties of MSX, SX-I, and SX-II...

Dispersive Component of Surface Free Energy and Related Thermodynamic Parameters... 

A plot of RTln Fn against u(yL ) according to Eq. (30) yields a linear slope of 2A(ys), from which the dispersive component of surface free energy of adsorption, yP, can be determined (60). 

All non-dispersion components of surface tension lumped together. 

All non-dispersion components of surface tension of i th material lumped together. Melt viscosity. 

Fowkes showed that the carbonyl stretching frequency shifts to lower values as the dispersion component of surface tension increases. The following empirical relationship was proposed ... 

For non-polar liquids, the dispersion component is essentially the total surface tension (see Eqn. 3). For polar liquids, the dispersion component of surface tension can be obtained using Eqn. 4 after measuring both surface tensions and interfacial tension, provided that... 

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. 

Table 7 contains some values of the polar and dispersive components of surface free energy [57] for some polymers obtained using the geometric and harmonic mean methods. It can be seen that they are in good agreement. 

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