SURFACE CHARACTERIZATION OF CHLORINATED SYNTHETIC VULCANIZED STYRENE-BUTADIENE RUBBER USING CONTACT-ANGLE MEASUREMENTS, INFRARED-SPECTROSCOPY AND XPS

The surface of a sulfur-vulcanized synthetic styrene-butadiene rubber (SBR) was treated with ethyl acetate solutions containing different am ounts of trichloroisocyanuric acid (TCI). The chlorinated SBR surfaces were characterized using contact angle measurements (water, ethane di ol, n-hexadecane), infra-red (IR) spectroscopy and XPS. Chlorination p roduced an increase of surface Free energy which was mainly due to the enhancement of the acid-base component of the surface free energy, wh ich remained almost unchanged when the amount of TCI was increased. De pending on the amount of chlorination agent, several chemical species were present on the SBR surface: i) For low amounts of TCI (up to 2 wt %), mainly chlorinated hydrocarbon and C-O species were present on the surface; ii) For medium amounts of TCI (between 2 and 5 wt%), an exce ss of unreacted TCI remained on the surface and a relatively small amo unt of isocyanuric acid was deposited; iii) For high amounts of TCI (l arger than 5 wt%), a weak boundary layer (mainly composed of isocyanur ic acid) was formed on the surface and thus the effects due to chlorin ation were decreased. There was good agreement between the experimenta l results obtained with contact angle measurements and XPS because bot h provided information on a surface region close to 100 Angstrom, wher eas IR spectroscopy results showed deeper penetration of the chlorinat ing agent into the SBR surface. The estimated thickness of the chlorin ated layer was near 5000 Angstrom as estimated from XPS measurements o f SBR surfaces modified by argon ion bombardment.