THE INFLUENCE OF DIFFERENT BRASS PRETREATMENTS ON RUBBER METAL-BONDING - INVESTIGATED BY ANALYTICAL ELECTRON-MICROSCOPY

Brass samples (thin foils or plates) were pretreated either by etching with aqueous HCI or by rubbing with emery cloth. A mixture of cis-1,4-polybutadiene with sulfur and N,N-dicyclohexyl-2-benzothiazylsulfenamide was vulcanized in contact with the brass surfaces. The bonding layers were investigated by analytical electron microscopy (AEM). Two preparation techniques for AEM were used, namely cryo-ultramicrotomy to obtain cross sections (applied to foils), or separating ultrathin surface layers with an aqueous HCI/FeCl3 solution (applied to plates). Across the bonding layers, various crystallographic structures and chemical compositions were found, depending on the pretreatment of the brass.