Elastomer-elastomer autohesion-interphase gradient of elastic modulus

The effect of migration on the vulcanizing ingredients is considered when t wo sheets of carbon black reinforced polyisoprene are brought into contact. Two formulations (conventional and efficient ones) are chosen. The formati on of macroscopic interphases on both sides of the interface is shown by me asurements of local modulus by microindentation. The local concentration of sulfur is determined by energy dispersive X-rap analysis. Near the interfa ce, the modulus is always higher than in the bulk of the sheets although th e interfacial strength may be quite low. Co-crosslinking of the chains in t he interphase at the molecular level and macroscopic thick interphases are two important aspects of elastomer-elastomer joints.