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The properties of the interphase between Twaron aramid fibres and polymer matrix systems can be optimized by a surface treatment process of the fibres. In this work, x-ray photoelectron spectroscopy and low-energy ion scattering have been used to analyse the surface layers, whereas the adhesion was measured by a bundle pull-out experiment. From the results, we succeeded in establishing a relation between the surface treatment, the resulting chemical/elemental surface composition and the adhesion to an epoxy matrix.

The use of aramid fibers as a reinforcing material in both tires and mechanical rubber goods, such as hoses, belts, etc., is growing. In these dynamic applications, the adhesion between fiber and rubber is critical. This can be optimized by activating the aramid with an epoxy formulation, followed by RFL (Resorcinol Formaldehyde Latex) treatment.In the past, various combinations of analytical techniques have been used to study the relationship between the fiber surface treatment, the resulting microscopic interphase structure and the macroscopic rubber properties. The fundamental knowledge acquired from these past studies has been exploited here to investigate the effect of oily finish components on the aramid-rubber adhesion. For this purpose, aramid yarn has been treated with various combinations of an adhesion improving (epoxy-amine) component and a processability improving (oily) component.Contrary to general belief, the oily components do not directly reduce the SPAF (Strap Peel Adhesion Force) to rubber, rather show some positive effect. Furthermore, there is a relative broad 'safe' oil range, i.e., fluctuations in the amount of oil will not directly lead to adhesion problems. This is in line with earlier observations, but this study using appropriate analytical techniques provides quantitative confirmation and additional understanding of the fundamental principles behind these effects.

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