Polar component of surface energy

Wetting. In the case of low surface energy solids, such as polymers, the dispersive and polar components of surface energy are easily determined through contact angle... 

An example of a diagram obtained in the case of the two-phase liquid (hydrocarbons H and formamide F) method is shown in Figure 5. As pointedLout in the Methods section, the slope of the straight line leads to the value of Ys - The surface polarity or polar component of surface energy is determined from the intercept. 

Fig. 18.5 Polar component of surface energy of plasma polymers as a function of the number of functional groups in them.

In contrast, it was found that in bonding a polyurethane to float glass [39], that work of adhesion was not an accurate predictor of joint strength, but there was a linear relationship between strength and the polar component of surface energy. 

Sample Fraction of few-unit silicon-oxygen rings, % Density, g/cm Melting point, K Surface energy, mJ/m A polar component of surface energy Refractive index... 

Lopez and Wilkes [73] have reported that the low temperature of crystallization and low-molecular-weight PPS favored surface nucleation, and the nucleating ability of carbon fibers was dependent on the polarity of the carbon surface. Also, an inverse relationship was observed between the value of polar component of surface energy and the nucleating efficiency [72]. 

Figure 5.24 shows the effect of oxidation on dispersive and polar components of surface free energy. Carbon fibers were exposed to plasma treatment in the presence of various ratios of CF4 and O2. The untreated sample and the samples exposed to a substantial concentrations of oxygen show increase in the polar component. Fligh concentrations of CF4 gas reduced its dispersive component and converted the surface to a PTFE-like material as confirmed by XPS studies. 

Wu has proposed to separate the surface energy into non-polar (dispersion) and polar components (Eq. (2.12)). The subscripts d and p designate non-polar (dispersion) and polar components, respectively. The concept of the additive nature of surface energy components has been accepted by a number of researchers such as Fowkes ° and Meyer et al. The polar component of surface tension includes various dipole interactions and hydrogen bonding. The various components have been lumped together to simplify the discussions. The dispersion component includes the nonpolar fraction of surface energy. Fractional polarity is defined by Eq. (2.13) and non-polarity by Eq. (2.14). 

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... 

Table 1. Values of dispersion (y ) and polar (yP) components of surface energy...

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. 

Geometric mean approximation Dispersive and polar components of solid surface energy are found by solving yiv(l +COS0) = 2(y,Xf + 2(y Yl S An extension of GGF equation ysa predicted is significantly higher than the critical surface tension. [84]... 

---