Migration of Processing Oils of Thermoplastic Rubber Treated with RF Plasma

Abstract

The surface modifications produced by a RF plasma treatment on a thermoplastic styrene-butadiene-styrene rubber-SBS-with a considerable amount of processing oils in its formulation (TRO) have been studied and compared to the modifications produced on an oil-free SBS rubber (TRF). The modifications produced by the plasmas on the rubber surface depended on the nature of the gas used to generate the plasma. Thus, argon plasma favored the migration of processing oils to the TRO rubber surface, producing a weak oily layer that prevented interaction of rubber with a polyurethane adhesive. On the other hand, oxygen and carbon dioxide plasmas produced important ablation of the rubber surface which resulted in a partial (CO 2 plasma) or total (O 2 plasma) removal of processing oils from the rubber surface and the creation of polar moieties that increased adhesion of the rubber surface towards a polyurethane adhesive.

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

“…The migration of processing oils in SBS rubbers treated with low‐pressure plasma has been previously reported 11. Two block SBS rubbers with and without processing oils in their formulations were treated with argon, carbon dioxide and oxygen low‐pressure plasmas for 0.5–10 min.…”

“…Radiation‐based treatments (corona discharge,6–8 ultraviolet,9, 10 low11–17 and atmospheric pressure or plasma torch18, 19 plasmas) for surface modification of rubber have been proved to be efficient to improve wettability and adhesion properties. In the case of plasma treatments, the gas nature, the time of treatment and the reactor configuration, among other, determine the extent of surface modification of polymers.…”

“…If polar groups are formed, the wettability should increase. The plasma treatment produces a decrease in the atomic percentage of carbon, which in the case of styrene–butadiene rubber (SBR) is due to the removal of paraffin wax from the surface 11. Furthermore, it has been shown12, 13 that the treatment of rubber with oxygen, air or argon‐oxygen low pressure plasmas caused oxidation by creation of CO groups; furthermore, the formation of CN groups on vulcanized rubber surface treated with oxygen or nitrogen low pressure plasma has also been observed 14.…”

“…There are few studies in the scientific literature dealing with the surface modification of synthetic rubber by low‐pressure plasma, and most of them are devoted to styrene–butadiene–styrene (SBS)11–13 and sulphur vulcanized SBR 14–17. Tyczkowski et al compared the effectiveness of the treatment with non‐equilibrium atmospheric‐pressure and low‐pressure plasma treatments of SBS rubber 12, 13.…”

Atmospheric plasma treatment of rubber and its effect on surface characteristics

“…The peak at the wavenumber of 3316 cm -1 can be assigned to stretching vibrations of υ(OH) and it can be seen an increase of relative intensity of peaks depending on plasma treatment position and time, for T301, T302 and T102. Typical peaks of the rubber polymer matrix were observed in the area between 3000 cm -1 to the 2840 cm -1 related to the symmetric and asymmetric stretching vibrations of CH, -CH 2 and -CH 3 [43][44][45][46][47][48][49][50][51][52]. Stretching vibrations of υ(CH) from the styrene butadiene rubber were observed near the wavenumber of 3000 cm -1 , overlapping stretching vibrations of υ(C=C-H) of natural rubber.…”