MECHANISM BY WHICH PRECIPITATED SILICA IMPROVES BRASS-COATED WIRE-TO-NATURAL RUBBER ADHESION

Quantitative determination of elements in the interfacial growth layer formed on brass-coated wire when reacted in squalene suspensions cont aining carbon black and curatives, with and without precipitated silic a and an organocobalt adhesive, was accomplished by using direct surfa ce characterization techniques: Scanning Electron Microscopy with Ener gy Dispersive Analysis of X-rays (SEM-EDX), Auger Electron Spectroscop y (AES), X-ray Photoelectron Spectroscopy (XPS) and Proton Induced X-r ay Emission (PIXE) Spectroscopy. The effects on elemental changes in t he interfacial growth layer upon addition of silica and/or cobalt neod ecanoate to the squalene suspensions were statistically analyzed. Sinc e the mechanism for silica improvement of brass-coated wire-to-rubber adhesion was previously shown not to be a simple effect of improving r ubber physical properties, a chemical mechanism is proposed involving silica to reduce the thickness of the interfacial growth layer and to change the relative concentration of compounds formed in the interfaci al growth layer.