Application of the surface free energy concept in polymer processing

Author： Jacobasch H.-J. Grundke K. Mäder E. Freitag K.-H. Panzer U.

ISSN： 1568-5616

Source： Journal of Adhesion Science and Technology, Vol.6, Iss.12, 1992-01, pp. : 1381-1396

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Abstract

The surface characteristics of variously treated carbon and glass fibres have been determined by contact angle measurements (using a capillary rise technique), inverse gas chromatography, and zeta potential measurements. The contact angles of water and methylene iodide were used to calculate the dispersive and non-dispersive components of the fibre surface free energy by applying the geometric mean approach, and the approach by Fowkes to estimate the acid-base term of the thermodynamic work of adhesion. The results obtained correlate with those of inverse gas chromatographic and zeta potential measurements. The non-polar surface character of the carbon fibre can be altered by oxidizing, or finishing the fibres with an epoxy resin. The acid-base term of the thermodynamic work of adhesion, W^ab_a, and the non-dispersive component of the surface free energy, γ^p_s, are increased drastically by these treatments. Treatment of the 'high-energy' glass fibre surface with an aminosilane results in a relatively low surface free energy with basic surface groups. When epoxy dispersions were used for sizing the glass fibres, the surface free energy increased without changing the basic surface character. A direct correlation between the surface-energetic properties of the fibres and the mechanical behaviour of the fibre-reinforced polyamide composites was not generally found.