Adhesion activation of Twaron Aramid Fibers
T. Mathew; Teijin Aramid
Aramid fibers are successfully used as reinforcing material in a growing number of rubber applications such as tires, hoses, and belts. In these dynamic applications, optimal transfer of loads and stresses from the rubber matrix to the reinforcing fiber is required. In order to achieve this, the interfacial adhesion is optimized by using a Resorcinol Formaldehyde Latex (RFL) based dipping system as chemical and physical “bridge” between the fiber cord and the rubber matrix.
In order to improve the interaction between fiber and RFL, the aramid is generally “pre-activated” with an epoxy based dipping system or an epoxy based spin finish. The pre-activation process results in hydroxyl groups fixated at the fiber surface, available for reaction with the RF part of the RFL dip. Plasma treatment has been investigated as potential alternative for the epoxy treatment. Several parameters have been considered, e.g. yarn versus cord treatment, presence of spin finish during treatment, and storage time between treatment and RFL dipping. By combining surface analytical data with rubber adhesion evaluation results, understanding can be reached about process/performance relations and conclusions can be drawn on the feasibility of epoxy replacement by plasma treatment.