ABSTRACT
In light of this, it is necessary to modify the cords surface before they can participate in a composite material. The following four different theories have been proposed to explain the adhesion strength between two materials: (a) mechanical interlocking theory, (b) electrostatic theory, (c) diffusion theory and (d) adsorption theory. These theories can, individually or in combination, be used to describe almost every kind of adhesion phenomenon [2]. As a standard method which satisfies the adsorption theory for the improvement of adhesion strength between the reinforcing polymer cords and the rubber matrix is the well-known RFL system (chemical modification of PET cords typically used in tire industry). According to this system, the cords surfaces are treated with either a solution or emulsion consisting of resorcinol, formaldehyde, and latex SBR, natural or vinyl pyridine rubber, followed by thermal treatment at a temperature higher than 200◦C [3, 4]. However, this method is inadvisable because of the necessity to treat the surface with epoxy resin or blocked isocyanides (EBI system). It is evident that high cost in time, energy and a negative effect on the environment are accompanied in this case. Moreover, RFL is very sensitive to exposure to oxygen, ozone, nitrogen oxides and ultraviolet light. Exposure to these enviromental factors during storage can significantly decrease adhesion of RFL coated cords to rubber [5].
