Interfacial acid-base function theory

The interfacial acid-base function theory was put forward the first time in 1962 by Fowks. This theory holds that the filler and polymer matrix of a composite material can be treated as a generalized acid or alkali. When the surfaces of the filler and polymer matrix have different acids or alkalis, they are easy to combine. The greater their difference in pH, the more easily they will combine. When the surfaces of the filler and polymer matrix have the same acid or alkali, the surface of the filler should be modified to change its pH value. The different surface pH values are beneficial to improve the bonding strength between the reinforced material and polymer matrix and improve the performance of filled plastics. 

Acid parameters E and alkaline parameters C can be used to show the acid and alkaline values of the surface of materials. To measure the E and C values of material surfaces, R. S. Drago proposed the famous Formula 2.2  

AH = the enthalpy change of interaction between two substances A and B E = the acid parameter C = the alkaline parameter 

AH can be measured by inverse gas chromatography, as follows. The solid analyte is installed in gas chromatography as a solid stationary phase, a solvent with known values of C and E is used as a probe, and specific retention volume v° is measured at different temperatures. Then Formula 2.3 is used to calculate the enthalpy change of the interaction with the stationary phase. 

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Figure 7 Plots of potential energy of interaction as a function of the distance H between the surfaces of identical spherical particles with radius a = I pm. Top clasHcal DLVO theory. Bottom Exterxled DLVO approach. The following values were used for the calculations = 30 mV 1 1 electrolyte concentration 10 - M Mamaker constant = 2 X lO J acid-base component of the solid-liquid interfacial toiuon — 10 mJ/ni See text for details.

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