Influence of the Configuration of the Plasma Chamber on the Surface Modification of Synthetic Vulcanized Rubber Treated with Low‐pressure Oxygen RF Plasma

Abstract

Three different configurations of RF low‐pressure oxygen plasmas were used to modify the surface of vulcanized styrene–butadiene rubber. Direct, etching and downstream oxygen plasma treatments of the rubber were carried out for length of treatment between 1 and 10 min. The oxygen plasma treated rubber surfaces were characterized by ethylene glycol contact angle measurements, ATR‐IR and XPS spectroscopy and scanning electron microscopy (SEM). Adhesion of the oxygen plasma treated rubber to polyurethane adhesive was carried out by means of T‐peel test and the loci of failure of the joints were characterized by means of ATR‐IR spectroscopy. Three different oxygen plasma configurations obtained by changing the position of the rubber sample in the plasma chamber and by changing the shelves (power, ground, floating) were used to modify the extent of surface modification and the temperature reached on rubber surface. The direct oxygen plasma was the most aggressive treatment and the secondary downstream plasma the less one. The increase in the length of the oxygen plasma treatment allowed the most efficient removal of antiozonant paraffin wax from the as‐received rubber. Furthermore, the oxygen plasma treatments created CO moieties on the rubber surface. On the other hand, only 1 min treatment time was sufficient to decrease noticeably the contact angle value on the rubber surface, irrespective of the oxygen plasma chamber configuration and the length of treatment. Oxygen plasma treatment caused surface oxidation and ablation on the rubber surface, as well as an increase of the temperature that also determined the extent of paraffin wax migration, the migration was favoured for temperature higher than 45 °C. Finally, the migration of paraffin wax was produced for at least 24 h after oxygen plasma treatment and poor adhesion to polyurethane adhesive was obtained, due to the creation of a weak boundary layer of paraffin wax at the rubber–polyurethane interface. The migration of paraffin wax caused during plasma treatment was the dominant factor in decreasing the adhesion of rubber to polyurethane adhesive.

Influence of Plasma Chamber Set‐Up on the Surface Modification of Non‐Vulcanized and Pure SBR Rubber Treated at Radio‐Frequencies Air Plasma

“…This is only true if the steady‐state is reached. Otherwise, the substrate temperature rises as a function of time to reach equilibrium . Our OES results confirmed the steady‐state as the intensity of the bands did not vary with time and kept constant after 20 s of the plasma ignition which is lower than all the exposure times used (>30 s).…”

“…They can also react together, inducing cross‐linking at the topmost surface layer. It is also well demonstrated in the literature that rubber material experiences some heating during low‐pressure plasma treatment . The temperature reached by the rubber is generally influenced by the plasma parameters but also by the configuration of the plasma used.…”

Ultraviolet–ozone surface cleaning of injection‐molded, thermoplastic microcantilevers

“…Among others, the nature of the gas, the time of treatment, and the reactor configuration determine the extent of surface modification of polymers in plasma treatment . Treatment with oxygen plasma causes oxidation of surface due to ion bombardment and free radicals generated during the treatment . In addition, plasma removes the polymer layer by ablation …”

“…Treatment with oxygen plasma causes oxidation of surface due to ion bombardment and free radicals generated during the treatment . In addition, plasma removes the polymer layer by ablation …”

Improved Surface and Adhesion Properties of Wood-Polyethylene Composite by Treatment with Argon–Oxygen Low Pressure Plasma

“…It has been shown that the configuration of the plasma chamber during LPP treatment noticeably affected the extent of the surface modifications of rubber materials [23,24]. The different configurations of the shelves in the plasma chamber allow different plasma species of distinct energy to reach the material surface, and different extent of surface modifications can be produced.…”