REACTIVE COMPOUNDS FOR EFFECTIVE UTILIZATION OF SILICA

Bis(diisopropyl)thiophosphoryl disulfide (DIPDIS), diisopropyl thiopho sphoryl-N-oxydiethylene sulfenamide (DIPTOS), diisopropyl thiophosphor yl-N-oxydiethylene disulfide (DIPTOD), diisopropyl thiophosphoryl-2-be nzothiazole monosulfide (DIBMS), diisopropyl thiophosphoryl-2-benzothi azole disulfide (DIBDS) and bis(diisopropyl)thiophosphoryl monosulfide (DIPMS) react with silica and generate isopropyl alcohol as a result of rubber-DIPDIS-silica interactions. Increasing the amount of DIPDIS in the system brings about a corresponding increase in silica-rubber c oupling, resulting in enhancement of Delta T-f - Delta T-f modulus and tensile strength, The vulcanizates containing 14 mmol DIPDIS and 35 p hr of silica exhibit highest torque and tensile strength. This is comm ensurate with the optimum loading derived from Lee's method. The syner gistic system containing DIPDIS and N-oxydiethylene-2-benzothinzole su lfenamide (OPTS) provides a very useful combination of accelerators. T he vulcanizates obtained from this system exhibit highest torque and t ensile value even at a lower concentration of accelerator (DIPDIS:OBTS = 7:3.5) far the same loading of silica (35 phr).