Treatment of vulcanized styrene-butadiene rubber (SBR) with mixtures of Trichloroisocyanuric Acid and Fumaric Acid

In this study, mixtures of trichloroisocyanuric acid (TCI) and fumaric acid (FA) solutions were applied to a difficult-to-bond, vulcanized styrene-butadiene rubber (R2) to analyze the combined effect of both surface treatments. The treated R2 rubber surfaces were characterized using advancing contact angle measurements, ATR-IR and XPS spectroscopy, and SEM. T-peel tests of treated R2 rubber/ polyurethane adhesive/leather joints have been obtained in order to quantify the adhesion properties. The wettability of R2 rubber was improved by treatment with 3 wt% TCI/EA (ethyl acetate) or 0.5 wt% FA/EtOH, and lower contact angles were obtained by treatment with both 3 wt% TCI/EA and 0.5 wt% FA/EtOH. The improved wettability was ascribed to the creation of carbon-chlorine moieties, the removal of zinc stearate and paraffin wax, and the creation of surface roughness on the R2 rubber surface. Treatment of R2 rubber with 3 wt% TCI/EA before or after treatment with 0.5 wt% FA/EtOH, or with a solution containing 3 wt% TCI/EA + 0.5 wt% FA/EtOH mixture produced a noticeable increase in peel strength. Always, the effects of the treatment of R2 rubber with 3 wt% TCI solution were dominant over those produced by treatment with 0.5 wt% FA solution in ethanol (FA/EtOH). On the other hand, the treatment of R2 rubber with 3 wt% TCI/EA + 0.5 wt% FA/EtOH mixture was more effective than the treatment with 0.5 wt% TCI/EA+ 2 wt% FA/EtOH because the lower amount of chlorinating agent in this mixture.     

SURFACE MODIFICATIONS ON EVA TREATED WITH SULPHURIC ACID

In this study, treatment with sulphuric acid was used to increase the adhesion of an ethylene-vinyl acetate copolymer containing 20 wt% vinyl acetate (EVA20). The treatment with sulphuric acid improved the wettability of EVA20 due to thecreation of different oxygen and sulphonic acid moieties on the surface. The treatment also created cracks and heterogeneities on the EVA20 surface, and enhanced T-peel strength values of EVA20/polychloroprene adhesive+5 wt% isocyanate joints were obtained. The loci of failure of the joints were mixed, i.e. , adhesional and cohesive in the adhesive. Peel strength values of both as-received and sulphuric acid-treated EVA20/polychloroprene adhesive joints increased after ageing at 50°C and 95 wt% relative humidity for 72 because the complete cure of the adhesive was thereby was produced. The durability of the EVA20 treated with sulphuric acid was monitored between 15 min and 5 years. High peel strength values were obtained for times up to 61 days; the joints produced with the treated EVA20 five years after treatment showed lower peel strength value due to the creation of a weak boundary layer produced by reaction of the residual sulphuric acid on the surface with EVA20. On the other hand, different experimental variables in the treatment of EVA20 with sulphuric acid were considered. The optimum treatment conditions for EVA20 were obtained by immersion in highly concentrated sulphuric acid (96 wt%) for one minute followed by neutralisation with ammonium hydroxide.     

Surface modifications on eva treated with sulphuric acid

In this study, treatment with sulphuric acid was used to increase the adhesion of an ethylene-vinyl acetate copolymer containing 20 wt% vinyl acetate (EVA20). The treatment with sulphuric acid improved the wettability of EVA20 due to thecreation of different oxygen and sulphonic acid moieties on the surface. The treatment also created cracks and heterogeneities on the EVA20 surface, and enhanced T-peel strength values of EVA20/polychloroprene adhesive+5 wt% isocyanate joints were obtained. The loci of failure of the joints were mixed, i.e. , adhesional and cohesive in the adhesive. Peel strength values of both as-received and sulphuric acid-treated EVA20/polychloroprene adhesive joints increased after ageing at 50°C and 95 wt% relative humidity for 72 because the complete cure of the adhesive was thereby was produced. The durability of the EVA20 treated with sulphuric acid was monitored between 15 min and 5 years. High peel strength values were obtained for times up to 61 days; the joints produced with the treated EVA20 five years after treatment showed lower peel strength value due to the creation of a weak boundary layer produced by reaction of the residual sulphuric acid on the surface with EVA20. On the other hand, different experimental variables in the treatment of EVA20 with sulphuric acid were considered. The optimum treatment conditions for EVA20 were obtained by immersion in highly concentrated sulphuric acid (96 wt%) for one minute followed by neutralisation with ammonium hydroxide.     

SURFACE MODIFICATIONS AND ADHESION OF VULCANIZED SBR RUBBER TREATED WITH RF PLASMAS OF DIFFERENT GASES

The surface modifications produced by treatment of a synthetic vulcanized styrene-butadiene rubber (R1) with oxidizing (oxygen, air, carbon dioxide) and nonoxidizing (nitrogen, argon) RF plasmas have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the treatment depended on the gas atmosphere used to generate the RF plasma. In general, acceptable adhesion values of treated R1 rubber were obtained for all plasmas, except for the nitrogen plasma treatment during 15?min, due to the creation of weak layers of low molecular weight moieties on the outermost R1 rubber layer. A toluene wiping of the 15?min N₂-plasma–treated R1 rubber surface removed those moieties, and increased adhesion was obtained. On the other hand, the air, carbon dioxide, and oxygen plasmas produced ablation of the R1 rubber surface, whereas mechanical degradation was not produced by treatment with the Ar plasma.     

SURFACE MODIFICATIONS AND ADHESION OF VULCANIZED SBR RUBBER TREATED WITH RF PLASMAS OF DIFFERENT GASES

The surface modifications produced by treatment of a synthetic vulcanized styrene-butadiene rubber (R1) with oxidizing (oxygen, air, carbon dioxide) and nonoxidizing (nitrogen, argon) RF plasmas have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the treatment depended on the gas atmosphere used to generate the RF plasma. In general, acceptable adhesion values of treated R1 rubber were obtained for all plasmas, except for the nitrogen plasma treatment during 15 min, due to the creation of weak layers of low molecular weight moieties on the outermost R1 rubber layer. A toluene wiping of the 15 min N₂-plasma-treated R1 rubber surface removed those moieties, and increased adhesion was obtained. On the other hand, the air, carbon dioxide, and oxygen plasmas produced ablation of the R1 rubber surface, whereas mechanical degradation was not produced by treatment with the Ar plasma.