DETERMINATION OF THE MODES OF ACTION OF A CATIONIC SURFACTANT FOR PROPERTY DEVELOPMENT IN CARBON-BLACK FILLED NATURAL-RUBBER COMPOUNDS

Work to separate the contributions of fatty diamine surfactant (termed a multifunctional additive [MFA]) to property development, from masti cation, elastomer-filler interface and crosslink density effects has b een carried out. Improvement in mechanical properties resulting from t he MFA is dominated by its effect on carbon black dispersion, compared with its effect on crosslink density. Results show that there is a sl ight improvement in resistance to crack initiation (tensile test) and a substantial improvement in resistance to crack growth (tear strength ) as MFA level increases compared with the results for control compoun ds (extended mixing time compounds). This improvement is attributed to the influence of the MFA on energy dissipation at the rubber-carbon b lack interface.