Tubeless tire has the innerliner for air impermeable layer for which butyl rubbers are often used. Butyl rubbers hardly adhere to the other tire components consisting of diene rubber compounds, e.g. blends of natural rubber, styrene-butadiene rubber and butadiene rubber. To solve this problem, the blend method of butyl rubber and diene rubber was proposed: however the adhesion has not been improved to a desired level.
In this article, we applied dynamic vulcanization for halogenated butyl rubber/natural rubber blend and successfully accomplished high adhesive strength (three times) without sacrificing the low air permeability. By transmission electron microscopy (TEM) and atomic force microscopy (AFM) analyses, the high adhesive strength was shown to be achieved by a unique morphology of butyl rubber-rich particles in the NR-rich matrix which is faced to diene rubber layer. The partial miscibility seems to be caused by a shear-dependent phase dissolution under high shear fields during dynamic vulcanization and succeeding phase decomposition. The dissolution-decomposition mechanism was supported by the development of regularly separated texture with periodic distance of sub-, um as observed by TEM and scanning electron microscopy (SEM) and the gradual change in concentration profile as revealed by AFM, both of which are characteristic to the spinodal decomposition; i.e., phase decomposition from single-phase mixture.

View full abstract

It is quite important for designing earthquake resistant tanks to estimate water pressures acting on the tank walls during a strong earthquake. Sloshing reponses induced by strong earthquakes in a rectangular model tank were studied numerically. The nonlinear fluid dynamic (Navier-Stokes) equations were solved to treat the large sloshing problems for which the conventional theory cannot be applied. For the confirmation of the analyses, a series of shaking table tests were conducted. Impact pressures on the roof and roof vibration were measured using several earthquake loading recorded at the 1995 Great Hanshin earthquake. The agreements between the experiments and the numerical results were fairly good and the numerical methods were proved to be a useful tool for designing earthquake resistant water storage tanks.

View full abstract

To investigate the effect of sliding speeds on the friction and wear of pattern abrasion of rubber, rubber wheel was rubbed against a plano-convex cylindrical lens at various sliding speeds from 1 to 1000mm/s. At low speeds less than 10mm/s the linear rate of wear and coefficient of friction increased with sliding speed. They were remained almost constant between sliding speeds of 10 and 100mm/s. Beyond sliding speeds of 100mm/s, the linear rate of wear decreased rapidly by a factor of 100. The same tendencies appeared with the coefficient of friction. At that time the rubber surface was covered with a sticky material.
The variations in the spacing of patterns and the spacing of striations with the sliding speeds were also studied. The spacing of patterns and the spacing of striations increased with sliding speeds at low speeds less than 10mm/s. They were almost constant between sliding speeds of 10mm/s and 100mm/s. At sliding speeds higher than 100mm/s, the spacing of patterns rapidly decreased. At that time the striations were not observed since the sticky material covered the abraded rubber surface.
The linear rate of wear, though discontinuous, was proportional to the third power of the pattern spacing at sliding speeds from 1 to 1000mm/s.

View full abstract

The Block and randam co-oligomers were synthesized by radical re- or co-telomerization of methacrylate monomer with fluoroalkyl group and styrene in carbon tetrabromide as a telogen. Using both co-oligomers, FKM/EPDM blends can be easily obtained and physical properties of vulcanized FKM/EPDM blends are improved compared with vulcanized control blend. From these results, it was recognized that co-oligomers show the action of compatibilizer and co-vulcanizing agent. The effect of surface modification of block co-oligomer on EPDM vulcanizates was remarkable, but the difference between block and randam co-oligomer on physical properties of rubber blends was poorly characterized.

View full abstract