Surface Modification of Natural Vulcanized Rubbers by Atmospheric Dielectric Barrier Discharges Plasma Treatments

A natural vulcanized rubber was treated by atmospheric dielectric barrier discharges to improve its adhesion to silicone adhesive. The different operating conditions were: (i) the nature of the plasma gas associated or not with organic precursors such as acetic acid or allyl alcohol, (ii) the concentration of the precursors in the gas phase, (iii) the power discharge (between 500 and 1000 W) and (iv) the treatment time (between 18 and 30 s). The surface modifications induced by the plasma treatments were characterized by water contact angle measurements and XPS analyses. T-peel tests were carried out to evaluate the influence of the surface modifications on the adhesion properties of the treated rubber. The efficiency of plasma treatments with the use of allyl alcohol has been proved for the adhesion improvement of natural vulcanized rubbers to a silicone adhesive (increase by a factor of 10). XPS analysis revealed that this treatment induced an increase of the total oxygen amount in the sample with the preferential formation of C-O bonds, which might explain the adhesion improvement observed.