Chlorination of vulcanized SBR rubber by immersion or brushing in TCI solutions

Abstract

The effectiveness of the chlorination treatment of synthetic vulcanized styrene-butadiene rubbers is determined by several experimental variables. In this study, trichloroisocyanuric acid (TCI) solutions in butanone have been used as chlorinating agents for a difficult-to-bond vulcanized styrene-butadiene rubber (R2). The influence of the TCI concentration (0.5 and 2 wt% TCI/MEK) was studied and a comparison between the immersion and brushing procedures to apply the chlorinating agent has been carried out. Characterization of the chlorinated surfaces was carried out using contact angle measurements (water, 25°C), ATR-IR spectroscopy, and scanning electron microscopy (SEM). T-peel tests on similarly treated R2 rubber/polyurethane adhesive joints were carried out to quantify adhesion. The chlorination by immersion of R2 rubber with TCI/MEK solutions was less effective than using a brush. The effects of the chlorination were similar using both procedures (creation of roughness, improved wettability, C Cl moieties formation and deposition of TCI particles), but the extent of the modifications was more marked when using a brush. The higher concentration of chlorinating agent allows a higher degree of chlorination. Peel strength values were lower for brush-chlorinated R2 rubber because the migration of wax (which created a weak layer on the rubber surface) from the bulk to the R2 rubber surface was favoured. However, the presence of waxes on the R2 rubber surface still allowed a reasonable level of adhesion due to the predominance of polar moieties.

Keywords:

• RUBBER
• SURFACE TREATMENT BY HALOGENATION
• APPLICATION PROCEDURE
• CONTACT ANGLE MEASUREMENTS
• INFRARED SPECTRA
• PEEL STRENGTH
• SEM