Surface Characterization of Vulcanized Rubber Treated with Sulfuric Acid and its Adhesion to Polyurethane Adhesive

• Published in: The Journal of adhesion 2000-09, Vol.73 (2-3), p.135-160
• Main Authors: Cepeda-Jiménez, Carmen M., Pastor-blas, M. Mercedes, Ferrándiz-Gómez, Teresa P., Martín-Martínez, José Miguel
• Format: Article
• Language: English
• Subjects: ATR-IR spectroscopy; Contact angle; SBR rubber; SEM; Sulfuric acid; Surface treatment; T-peel strength
• ISSN: 0021-8464; 1545-5823
• DOI: 10.1080/00218460008029303

Modifications produced on a vulcanized styrene -butadiene rubber surface by treatment with sulfuric acid were studied and several experimental variables were considered. The treatment of R1 rubber with sulfuric acid produced a noticeable decrease in contact angle which was mainly ascribed to an increase in surface energy due to the formation of sulfonic acid moieties and C˭O bonds, and the removal of zinc stearate. The rubber surface swelled and became brittle as a result of the treatment, and when flexed microcracks were created. A rubber surface layer modification was produced with a consequent decrease in tensile strength and elongation-at-break values. The treatment enhanced the T-peel strength of R1 rubber/polyurethane adhesive joints and the locus of failure was cohesive in the rubber. The optimum immersion time in H 2 SO 4 solution was less than 1 min., and the reaction time in air was not found to be critical; the neutralization with ammonium hydroxide and the high concentration of the sulfuric acid (95 wt%) were essential to produce adequate effectiveness of the treatment.