Vinylpyridine Rubber (PBR)-Filler Interactions. II.

Abstract

Abstract This paper describes some reactions of vinylpyridine rubber with fillers. The work was done to learn if there is a chemical basis for the superior abrasion resistance of pyridine rubber treads. The results show that chemical factors are important when rubber-to-filler interaction is involved. The copolymerized pyridine groups of the rubber are absorbed readily onto the filler surface, especially when the pyridines are modified by complex formation with certain zinc salts or by conversion to pyridinium cation. Multiple adsorption generates a network. Those qualities associated with reinforcement are enhanced: viscosity (carbon black “stiffening”), “bound” rubber, electrical resistivity, modulus and resistance to tearing and to abrasion. The network bonds are, however, temperature dependent and can be erased by heating to 100° C. Adsorption of modified pyridines onto filler is like the mordant dyeing of fabrics. The pyridinium compound acts like a color “lake” adsorbed onto carbon black. Adsorption-bonding can be used to generate a portion of the modulus in sulfur-cured treads. For the same modulus, less sulfur is required, with a corresponding improvement in heat-aging.