Abstract
We inspected here whether the gel-network structure model of cross-linked rubber, which consists of three different regions, the gel-balls of very highly cross-linked, the molecular bundles of slightly cross-linked which connect the gel-balls each other and the uncross-linked regions, is valid or not in comparison with AFM observation and fractured surface of the real cross-linked rubber.
(1) AFM image shows that two domains of hard and soft exist in the cross-linked rubber, where the spherical hard domains are surrounded by the soft domains, thus both the domains are alternately arranged. At a large extension mutual movement of both the domains agrees well with the movement expected for both the cross-linked phase (gel-ball) and the uncross-linked phase in the gel-network structure model.
(2) Fracture patterns left on fractured surface for tear fracture, fatigue fracture and wear fracture of the crosslinked rubber indicate the existence of several weak boundaries in the cross-linked rubber. These weak boundaries are consistent with the intrinsic weakness of the gel-network structure, resulting from the weak boundaries between gel-balls.
(3) These results indicate that the gel-network structure model is suitable to express the inside real structure of the cross-linked rubber, qualitatively at least.
