TENSILE PROPERTIES AND MORPHOLOGY OF REINFORCED RUBBER VULCANIZATES

Abstract

Tensile properties of pure rubber, precipitated CaCO₃ filled and carbon black-reinforced SBR vulcanizates under biaxial extension were measured.Observation by electron-microscope under extension was done. In the case of biaxial extension, it is observed that the average extension ratio of rubber chains at break is proportional to the crosslink density to the minus one-half power and it is assumed that a fracture of speciman occurs when rubber chains are fully extended.In the same case, there are low-density, plane-like structures which are1000A thick and run parallel to the extension direction.Those low density structures may be related to the generation of energy elasticity of reinforced rubber.