Short Fiber-reinforced Rubber Research Articles

Friction of short‐fiber–reinforced rubber on wet surfaces

AbstractThe friction coefficient of short‐fiber–reinforced rubber (SFRR) was examined under dry and wet conditions. When the unfilled rubber is rubbed against a dry glass disk, the friction coefficient is higher than that of the SFRR and decreases as contact pressure increases. On the other hand, the friction coefficient for the SFRR is relatively low, and decreases slightly with the increase of contact pressure. When the unfilled rubber is rubbed against a silicone oil–lubricated glass disk, the friction coefficient is lower than that in a dry condition, and decreases with increasing sliding speed to reach a minimum value. After that, it increases slightly with the increment of the sliding speed at the sliding speed range examined. The friction coefficient of the SFRR on the wet surfaces is lower than that of the unfilled rubber at low sliding speeds. With an increase in speed, the friction coefficient initially decreases, and then reaches a minimum value. After that, it increases with the increment of sliding speed. The minimum for the unfilled rubber and the SFRRs shifts toward lower sliding speeds when the contact pressure is increased. Therefore, under the condition of mixed lubrication at low speeds, the friction coefficient at low contact pressure is higher than that at high contact pressure. This trend is distinguishable as the fiber content of the SFRR is increased. The phenomena at high contact pressures arise from the reduction of effective surface roughness, as the unfilled rubber deforms and the SFRRs deflect because of the applied load. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 82–89, 2005

Effects of interphase conditions on the tensile and fatigue properties of short-fiber reinforced rubber

The effects of the amount of nylon-66 short-fiber and its bonding to a chloroprene rubber were studied. The following results were obtained: (a) The tensile strength of short-fiber reinforced rubber (SFRR) exhibits a dilution effect in each interphase. It was found that the interphase conditions have an important effect on the dilution ratio and the critical fiber content. The specimen with double coatings of the bonding agent and a rubber solution, becomes the best of 5 interphase models. Both the yield strength and tensile moduli significantly improve with fiber content. (b) The spring constant (SC) of unreinforced rubber decreases after the fatigue test, however, the SC of all reinforced rubbers increases. The change in SC of reinforced rubber decreases with fiber content. The better the interphase condition, the smaller the change of the SC. (c) The temperature of rubber increases about 2.6 fold after the fatigue test. The reinforced rubbers show a 1.4 to 2.2 fold increase in temperature. The temperature changes during the fatigue test of the reinforced rubbers decrease with increasing fiber content, as well as with improved interphase bonding.