In absence of cutting and folding on a two-roll mill, it is assumed that the radial mixing a powder in bank into band rubber on the roll surface was caused by rheological unit. It is thought that the rheological unit will be formed on the surface band rubber when the band rubber passes through from the bank to the nip of the roll.
Rubber powders was produced by comminution due to dynamic vulcanization of rubbers containing curing regents. Dynamic vulcanization was carried out in a two-dimensional internal mixer. The torque of a rotor axis, and temperature and pressure of the rubber increased when the vulcanization occurred. The same vulcanization was also carried out in a internal mixer, a sand mill and a two-roll mill.

It has been reported widely for more than half a century period that the crack growth rate increases abruptly and significantly in spite that the input strain energy release rate is kept constant, named a velocity jump, when rate of tear fracture of cross-linked rubbers approaches the velocity of elastic wave. This phenomenon is associated closely with the balance of elasticity and viscosity of the material and hence its glass transition behavior. Recently the authors summarized and defined this unstable behavior as an elastic-viscous transition phenomenon in fracture of rubber using an elastic-viscous transition diagram, where the diagram consists of three zones, each with a different fracture mode. These are an elastic-brittle fracture zone I, a viscous-ductile fracture zone III and an intermediate transition zone II between the elastic and viscous zones characterized by unstable stick-slip motions and the corresponding velocity jump. In the first half of this article, the authors show real aspects of these phenomena in detail focusing on the fracture surface formation and the stick-slip motion in the transition zone II and in the latter half we propose a new physical aspect for this transition phenomenon accompanied with velocity jump.

In the recent global environment, the ozone in the atmosphere near the surface of the earth is increasing due to the expansion of the ozone hole, the increase in the amount of ultraviolet rays, and the increase in NO_x.
Damage of vulcanized rubber suffered by ozone is quite large. Therefore, design of rubber formulation is necessary, such as increase of wax content and selection of HNBR with high conversion of hydrogenation, even though conventional vulcanized rubber with ozone resistance.

In this article, Flory’s theory on strain-induced crystallization of network polymer (published in 1947) is explained in an easy-to-understand manner. Regarding the derivation of mathematical formulas, their physical meanings are supplemented. When Flory’s explanations are interpreted, differences between 1940s and present days in knowledge about polymer crystals are considered. Some problems about the results of numerical calculations based on the theory are pointed out.